]> git.sesse.net Git - mlt/blobdiff - src/framework/mlt_consumer.c
make mlt_position type double
[mlt] / src / framework / mlt_consumer.c
index c6babd85637bc206caf0bc33b08d5ed6eab47f77..2791a0171b18148c5b2b49c13072e4d87ce545e3 100644 (file)
-/*
- * mlt_consumer.c -- abstraction for all consumer services
- * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
- * Author: Charles Yates <charles.yates@pandora.be>
+/**
+ * \file mlt_consumer.c
+ * \brief abstraction for all consumer services
+ * \see mlt_consumer_s
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
+ * Copyright (C) 2003-2010 Ushodaya Enterprises Limited
+ * \author Charles Yates <charles.yates@pandora.be>
+ * \author Dan Dennedy <dan@dennedy.org>
  *
- * This program is distributed in the hope that it will be useful,
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
  *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
-#include "config.h"
 #include "mlt_consumer.h"
 #include "mlt_factory.h"
 #include "mlt_producer.h"
 #include "mlt_frame.h"
+#include "mlt_profile.h"
+#include "mlt_log.h"
+
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <sys/time.h>
 
-static void mlt_consumer_frame_show( mlt_listener listener, mlt_properties owner, mlt_service this, void **args );
+/** Define this if you want an automatic deinterlace (if necessary) when the
+ * consumer's producer is not running at normal speed.
+ */
+#undef DEINTERLACE_ON_NOT_NORMAL_SPEED
 
-/** Public final methods
-*/
+/** This is not the ideal place for this, but it is needed by VDPAU as well.
+ */
+pthread_mutex_t mlt_sdl_mutex = PTHREAD_MUTEX_INITIALIZER;
 
-int mlt_consumer_init( mlt_consumer this, void *child )
+/** \brief private members of mlt_consumer */
+
+typedef struct
+{
+       int real_time;
+       int ahead;
+       mlt_image_format format;
+       mlt_deque queue;
+       pthread_t ahead_thread;
+       pthread_mutex_t queue_mutex;
+       pthread_cond_t queue_cond;
+       pthread_mutex_t put_mutex;
+       pthread_cond_t put_cond;
+       mlt_frame put;
+       int put_active;
+       mlt_event event_listener;
+       mlt_position position;
+       int is_purge;
+
+       /* additional fields added for the parallel work queue */
+       mlt_deque worker_threads;
+       pthread_mutex_t done_mutex;
+       pthread_cond_t done_cond;
+       int consecutive_dropped;
+       int consecutive_rendered;
+       int process_head;
+       int started;
+       pthread_t *threads; /**< used to deallocate all threads */
+}
+consumer_private;
+
+static void mlt_consumer_frame_render( mlt_listener listener, mlt_properties owner, mlt_service self, void **args );
+static void mlt_consumer_frame_show( mlt_listener listener, mlt_properties owner, mlt_service self, void **args );
+static void mlt_consumer_property_changed( mlt_properties owner, mlt_consumer self, char *name );
+static void apply_profile_properties( mlt_consumer self, mlt_profile profile, mlt_properties properties );
+static void on_consumer_frame_show( mlt_properties owner, mlt_consumer self, mlt_frame frame );
+
+/** Initialize a consumer service.
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self the consumer to initialize
+ * \param child a pointer to the object for the subclass
+ * \param profile the \p mlt_profile_s to use (optional but recommended,
+ * uses the environment variable MLT if self is NULL)
+ * \return true if there was an error
+ */
+
+int mlt_consumer_init( mlt_consumer self, void *child, mlt_profile profile )
 {
        int error = 0;
-       memset( this, 0, sizeof( struct mlt_consumer_s ) );
-       this->child = child;
-       error = mlt_service_init( &this->parent, this );
+       memset( self, 0, sizeof( struct mlt_consumer_s ) );
+       self->child = child;
+       consumer_private *priv = self->local = calloc( 1, sizeof( consumer_private ) );
+
+       error = mlt_service_init( &self->parent, self );
        if ( error == 0 )
        {
                // Get the properties from the service
-               mlt_properties properties = mlt_service_properties( &this->parent );
+               mlt_properties properties = MLT_SERVICE_PROPERTIES( &self->parent );
 
-               // Get the normalisation preference
-               char *normalisation = mlt_environment( "MLT_NORMALISATION" );
-
-               // Deal with normalisation
-               if ( normalisation == NULL || strcmp( normalisation, "NTSC" ) )
-               {
-                       mlt_properties_set( properties, "normalisation", "PAL" );
-                       mlt_properties_set_double( properties, "fps", 25.0 );
-                       mlt_properties_set_int( properties, "width", 720 );
-                       mlt_properties_set_int( properties, "height", 576 );
-                       mlt_properties_set_int( properties, "progressive", 0 );
-                       mlt_properties_set_double( properties, "aspect_ratio", 59.0 / 54.0 );
-               }
-               else
+               // Apply profile to properties
+               if ( profile == NULL )
                {
-                       mlt_properties_set( properties, "normalisation", "NTSC" );
-                       mlt_properties_set_double( properties, "fps", 30000.0 / 1001.0 );
-                       mlt_properties_set_int( properties, "width", 720 );
-                       mlt_properties_set_int( properties, "height", 480 );
-                       mlt_properties_set_int( properties, "progressive", 0 );
-                       mlt_properties_set_double( properties, "aspect_ratio", 10.0 / 11.0 );
+                       // Normally the application creates the profile and controls its lifetime
+                       // This is the fallback exception handling
+                       profile = mlt_profile_init( NULL );
+                       mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+                       mlt_properties_set_data( properties, "_profile", profile, 0, (mlt_destructor)mlt_profile_close, NULL );
                }
+               apply_profile_properties( self, profile, properties );
 
                // Default rescaler for all consumers
                mlt_properties_set( properties, "rescale", "bilinear" );
 
                // Default read ahead buffer size
                mlt_properties_set_int( properties, "buffer", 25 );
+               mlt_properties_set_int( properties, "drop_max", 5 );
 
                // Default audio frequency and channels
                mlt_properties_set_int( properties, "frequency", 48000 );
@@ -84,79 +132,332 @@ int mlt_consumer_init( mlt_consumer this, void *child )
                mlt_properties_set( properties, "test_card", mlt_environment( "MLT_TEST_CARD" ) );
 
                // Hmm - default all consumers to yuv422 :-/
-               this->format = mlt_image_yuv422;
+               priv->format = mlt_image_yuv422;
+               mlt_properties_set( properties, "mlt_image_format", mlt_image_format_name( priv->format ) );
+               mlt_properties_set( properties, "mlt_audio_format", mlt_audio_format_name( mlt_audio_s16 ) );
 
                mlt_events_register( properties, "consumer-frame-show", ( mlt_transmitter )mlt_consumer_frame_show );
+               mlt_events_register( properties, "consumer-frame-render", ( mlt_transmitter )mlt_consumer_frame_render );
+               mlt_events_register( properties, "consumer-thread-started", NULL );
+               mlt_events_register( properties, "consumer-thread-stopped", NULL );
                mlt_events_register( properties, "consumer-stopped", NULL );
+               mlt_events_listen( properties, self, "consumer-frame-show", ( mlt_listener )on_consumer_frame_show );
+
+               // Register a property-changed listener to handle the profile property -
+               // subsequent properties can override the profile
+               priv->event_listener = mlt_events_listen( properties, self, "property-changed", ( mlt_listener )mlt_consumer_property_changed );
 
                // Create the push mutex and condition
-               pthread_mutex_init( &this->put_mutex, NULL );
-               pthread_cond_init( &this->put_cond, NULL );
+               pthread_mutex_init( &priv->put_mutex, NULL );
+               pthread_cond_init( &priv->put_cond, NULL );
 
        }
        return error;
 }
 
-static void mlt_consumer_frame_show( mlt_listener listener, mlt_properties owner, mlt_service this, void **args )
+/** Convert the profile into properties on the consumer.
+ *
+ * \private \memberof mlt_consumer_s
+ * \param self a consumer
+ * \param profile a profile
+ * \param properties a properties list (typically, the consumer's)
+ */
+
+static void apply_profile_properties( mlt_consumer self, mlt_profile profile, mlt_properties properties )
+{
+       consumer_private *priv = self->local;
+       mlt_event_block( priv->event_listener );
+       mlt_properties_set_double( properties, "fps", mlt_profile_fps( profile ) );
+       mlt_properties_set_int( properties, "frame_rate_num", profile->frame_rate_num );
+       mlt_properties_set_int( properties, "frame_rate_den", profile->frame_rate_den );
+       mlt_properties_set_int( properties, "width", profile->width );
+       mlt_properties_set_int( properties, "height", profile->height );
+       mlt_properties_set_int( properties, "progressive", profile->progressive );
+       mlt_properties_set_double( properties, "aspect_ratio", mlt_profile_sar( profile )  );
+       mlt_properties_set_int( properties, "sample_aspect_num", profile->sample_aspect_num );
+       mlt_properties_set_int( properties, "sample_aspect_den", profile->sample_aspect_den );
+       mlt_properties_set_double( properties, "display_ratio", mlt_profile_dar( profile )  );
+       mlt_properties_set_int( properties, "display_aspect_num", profile->display_aspect_num );
+       mlt_properties_set_int( properties, "display_aspect_num", profile->display_aspect_num );
+       mlt_properties_set_int( properties, "colorspace", profile->colorspace );
+       mlt_event_unblock( priv->event_listener );
+}
+
+/** The property-changed event listener
+ *
+ * \private \memberof mlt_consumer_s
+ * \param owner the events object
+ * \param self the consumer
+ * \param name the name of the property that changed
+ */
+
+static void mlt_consumer_property_changed( mlt_properties owner, mlt_consumer self, char *name )
+{
+       if ( !strcmp( name, "mlt_profile" ) )
+       {
+               // Get the properies
+               mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+
+               // Get the current profile
+               mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+
+               // Load the new profile
+               mlt_profile new_profile = mlt_profile_init( mlt_properties_get( properties, name ) );
+
+               if ( new_profile )
+               {
+                       // Copy the profile
+                       if ( profile != NULL )
+                       {
+                               free( profile->description );
+                               memcpy( profile, new_profile, sizeof( struct mlt_profile_s ) );
+                               profile->description = strdup( new_profile->description );
+                       }
+                       else
+                       {
+                               profile = new_profile;
+                       }
+
+                       // Apply to properties
+                       apply_profile_properties( self, profile, properties );
+                       mlt_profile_close( new_profile );
+               }
+       }
+       else if ( !strcmp( name, "frame_rate_num" ) )
+       {
+               mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+               mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+               if ( profile )
+               {
+                       profile->frame_rate_num = mlt_properties_get_int( properties, "frame_rate_num" );
+                       mlt_properties_set_double( properties, "fps", mlt_profile_fps( profile ) );
+               }
+       }
+       else if ( !strcmp( name, "frame_rate_den" ) )
+       {
+               mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+               mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+               if ( profile )
+               {
+                       profile->frame_rate_den = mlt_properties_get_int( properties, "frame_rate_den" );
+                       mlt_properties_set_double( properties, "fps", mlt_profile_fps( profile ) );
+               }
+       }
+       else if ( !strcmp( name, "width" ) )
+       {
+               mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+               mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+               if ( profile )
+                       profile->width = mlt_properties_get_int( properties, "width" );
+       }
+       else if ( !strcmp( name, "height" ) )
+       {
+               mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+               mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+               if ( profile )
+                       profile->height = mlt_properties_get_int( properties, "height" );
+       }
+       else if ( !strcmp( name, "progressive" ) )
+       {
+               mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+               mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+               if ( profile )
+                       profile->progressive = mlt_properties_get_int( properties, "progressive" );
+       }
+       else if ( !strcmp( name, "sample_aspect_num" ) )
+       {
+               mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+               mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+               if ( profile )
+               {
+                       profile->sample_aspect_num = mlt_properties_get_int( properties, "sample_aspect_num" );
+                       mlt_properties_set_double( properties, "aspect_ratio", mlt_profile_sar( profile )  );
+               }
+       }
+       else if ( !strcmp( name, "sample_aspect_den" ) )
+       {
+               mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+               mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+               if ( profile )
+               {
+                       profile->sample_aspect_den = mlt_properties_get_int( properties, "sample_aspect_den" );
+                       mlt_properties_set_double( properties, "aspect_ratio", mlt_profile_sar( profile )  );
+               }
+       }
+       else if ( !strcmp( name, "display_aspect_num" ) )
+       {
+               mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+               mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+               if ( profile )
+               {
+                       profile->display_aspect_num = mlt_properties_get_int( properties, "display_aspect_num" );
+                       mlt_properties_set_double( properties, "display_ratio", mlt_profile_dar( profile )  );
+               }
+       }
+       else if ( !strcmp( name, "display_aspect_den" ) )
+       {
+               mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+               mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+               if ( profile )
+               {
+                       profile->display_aspect_den = mlt_properties_get_int( properties, "display_aspect_den" );
+                       mlt_properties_set_double( properties, "display_ratio", mlt_profile_dar( profile )  );
+               }
+       }
+       else if ( !strcmp( name, "colorspace" ) )
+       {
+               mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+               mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+               if ( profile )
+                       profile->colorspace = mlt_properties_get_int( properties, "colorspace" );
+       }
+}
+
+/** The transmitter for the consumer-frame-show event
+ *
+ * Invokes the listener.
+ *
+ * \private \memberof mlt_consumer_s
+ * \param listener a function pointer that will be invoked
+ * \param owner the events object that will be passed to \p listener
+ * \param self a service that will be passed to \p listener
+ * \param args an array of pointers - the first entry is passed as a frame to \p listener
+ */
+
+static void mlt_consumer_frame_show( mlt_listener listener, mlt_properties owner, mlt_service self, void **args )
 {
        if ( listener != NULL )
-               listener( owner, this, ( mlt_frame )args[ 0 ] );
+               listener( owner, self, ( mlt_frame )args[ 0 ] );
+}
+
+/** The transmitter for the consumer-frame-render event
+ *
+ * Invokes the listener.
+ *
+ * \private \memberof mlt_consumer_s
+ * \param listener a function pointer that will be invoked
+ * \param owner the events object that will be passed to \p listener
+ * \param self a service that will be passed to \p listener
+ * \param args an array of pointers - the first entry is passed as a frame to \p listener
+ */
+
+static void mlt_consumer_frame_render( mlt_listener listener, mlt_properties owner, mlt_service self, void **args )
+{
+       if ( listener != NULL )
+               listener( owner, self, ( mlt_frame )args[ 0 ] );
+}
+
+/** A listener on the consumer-frame-show event
+ *
+ * Saves the position of the frame shown.
+ *
+ * \private \memberof mlt_consumer_s
+ * \param owner the events object
+ * \param consumer the consumer on which this event occurred
+ * \param frame the frame that was shown
+ */
+
+static void on_consumer_frame_show( mlt_properties owner, mlt_consumer consumer, mlt_frame frame )
+{
+       if ( frame )
+               ( ( consumer_private*) consumer->local )->position = mlt_frame_get_position( frame );
 }
 
 /** Create a new consumer.
-*/
+ *
+ * \public \memberof mlt_consumer_s
+ * \param profile a profile (optional, but recommended)
+ * \return a new consumer
+ */
 
-mlt_consumer mlt_consumer_new( )
+mlt_consumer mlt_consumer_new( mlt_profile profile )
 {
        // Create the memory for the structure
-       mlt_consumer this = malloc( sizeof( struct mlt_consumer_s ) );
+       mlt_consumer self = malloc( sizeof( struct mlt_consumer_s ) );
 
        // Initialise it
-       if ( this != NULL )
-               mlt_consumer_init( this, NULL );
-
-       // Return it
-       return this;
+       if ( self != NULL && mlt_consumer_init( self, NULL, profile ) == 0 )
+       {
+               // Return it
+               return self;
+       }
+       else
+       {
+               free(self);
+               return NULL;
+       }
 }
 
 /** Get the parent service object.
-*/
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ * \return the parent service class
+ * \see MLT_CONSUMER_SERVICE
+ */
 
-mlt_service mlt_consumer_service( mlt_consumer this )
+mlt_service mlt_consumer_service( mlt_consumer self )
 {
-       return this != NULL ? &this->parent : NULL;
+       return self != NULL ? &self->parent : NULL;
 }
 
 /** Get the consumer properties.
-*/
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ * \return the consumer's properties list
+ * \see MLT_CONSUMER_PROPERTIES
+ */
 
-mlt_properties mlt_consumer_properties( mlt_consumer this )
+mlt_properties mlt_consumer_properties( mlt_consumer self )
 {
-       return this != NULL ? mlt_service_properties( &this->parent ) : NULL;
+       return self != NULL ? MLT_SERVICE_PROPERTIES( &self->parent ) : NULL;
 }
 
 /** Connect the consumer to the producer.
-*/
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ * \param producer a producer
+ * \return > 0 warning, == 0 success, < 0 serious error,
+ *         1 = this service does not accept input,
+ *         2 = the producer is invalid,
+ *         3 = the producer is already registered with this consumer
+ */
 
-int mlt_consumer_connect( mlt_consumer this, mlt_service producer )
+int mlt_consumer_connect( mlt_consumer self, mlt_service producer )
 {
-       return mlt_service_connect_producer( &this->parent, producer, 0 );
+       return mlt_service_connect_producer( &self->parent, producer, 0 );
 }
 
 /** Start the consumer.
-*/
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ * \return true if there was an error
+ */
 
-int mlt_consumer_start( mlt_consumer this )
+int mlt_consumer_start( mlt_consumer self )
 {
+       if ( !mlt_consumer_is_stopped( self ) )
+               return 0;
+
+       consumer_private *priv = self->local;
+
+       // Stop listening to the property-changed event
+       mlt_event_block( priv->event_listener );
+
        // Get the properies
-       mlt_properties properties = mlt_consumer_properties( this );
+       mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
 
        // Determine if there's a test card producer
        char *test_card = mlt_properties_get( properties, "test_card" );
 
        // Just to make sure nothing is hanging around...
-       mlt_frame_close( this->put );
-       this->put = NULL;
+       pthread_mutex_lock( &priv->put_mutex );
+       priv->put = NULL;
+       priv->put_active = 1;
+       pthread_mutex_unlock( &priv->put_mutex );
 
        // Deal with it now.
        if ( test_card != NULL )
@@ -164,13 +465,16 @@ int mlt_consumer_start( mlt_consumer this )
                if ( mlt_properties_get_data( properties, "test_card_producer", NULL ) == NULL )
                {
                        // Create a test card producer
-                       mlt_producer producer = mlt_factory_producer( NULL, test_card );
+                       mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( self ) );
+                       mlt_producer producer = mlt_factory_producer( profile, NULL, test_card );
 
                        // Do we have a producer
                        if ( producer != NULL )
                        {
                                // Test card should loop I guess...
-                               mlt_properties_set( mlt_producer_properties( producer ), "eof", "loop" );
+                               mlt_properties_set( MLT_PRODUCER_PROPERTIES( producer ), "eof", "loop" );
+                               //mlt_producer_set_speed( producer, 0 );
+                               //mlt_producer_set_in_and_out( producer, 0, 0 );
 
                                // Set the test card on the consumer
                                mlt_properties_set_data( properties, "test_card_producer", producer, 0, ( mlt_destructor )mlt_producer_close, NULL );
@@ -183,49 +487,95 @@ int mlt_consumer_start( mlt_consumer this )
                mlt_properties_set_data( properties, "test_card_producer", NULL, 0, NULL, NULL );
        }
 
+       // The profile could have changed between a stop and a restart.
+       apply_profile_properties( self, mlt_service_profile( MLT_CONSUMER_SERVICE(self) ), properties );
+
+       // Set the frame duration in microseconds for the frame-dropping heuristic
+       int frame_rate_num = mlt_properties_get_int( properties, "frame_rate_num" );
+       int frame_rate_den = mlt_properties_get_int( properties, "frame_rate_den" );
+       int frame_duration = 0;
+
+       if ( frame_rate_num && frame_rate_den )
+       {
+               frame_duration = 1000000 / frame_rate_num * frame_rate_den;
+       }
+
+       mlt_properties_set_int( properties, "frame_duration", frame_duration );
+
        // Check and run an ante command
        if ( mlt_properties_get( properties, "ante" ) )
-               system( mlt_properties_get( properties, "ante" ) );
+               if ( system( mlt_properties_get( properties, "ante" ) ) == -1 )
+                       mlt_log( MLT_CONSUMER_SERVICE( self ), MLT_LOG_ERROR, "system(%s) failed!\n", mlt_properties_get( properties, "ante" ) );
 
        // Set the real_time preference
-       this->real_time = mlt_properties_get_int( properties, "real_time" );
+       priv->real_time = mlt_properties_get_int( properties, "real_time" );
+
+       // For worker threads implementation, buffer must be at least # threads
+       if ( abs( priv->real_time ) > 1 && mlt_properties_get_int( properties, "buffer" ) <= abs( priv->real_time ) )
+               mlt_properties_set_int( properties, "_buffer", abs( priv->real_time ) + 1 );
+
+       // Get the image format to use for rendering threads
+       const char* format = mlt_properties_get( properties, "mlt_image_format" );
+       if ( format )
+       {
+               if ( !strcmp( format, "rgb24" ) )
+                       priv->format = mlt_image_rgb24;
+               else if ( !strcmp( format, "rgb24a" ) )
+                       priv->format = mlt_image_rgb24a;
+               else if ( !strcmp( format, "yuv420p" ) )
+                       priv->format = mlt_image_yuv420p;
+               else if ( !strcmp( format, "none" ) )
+                       priv->format = mlt_image_none;
+               else if ( !strcmp( format, "glsl" ) )
+                       priv->format = mlt_image_glsl_texture;
+               else
+                       priv->format = mlt_image_yuv422;
+       }
 
        // Start the service
-       if ( this->start != NULL )
-               return this->start( this );
+       if ( self->start != NULL )
+               return self->start( self );
 
        return 0;
 }
 
-/** An alternative method to feed frames into the consumer - only valid if
-       the consumer itself is not connected.
-*/
+/** An alternative method to feed frames into the consumer.
+ *
+ * Only valid if the consumer itself is not connected.
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ * \param frame a frame
+ * \return true (ignore self for now)
+ */
 
-int mlt_consumer_put_frame( mlt_consumer this, mlt_frame frame )
+int mlt_consumer_put_frame( mlt_consumer self, mlt_frame frame )
 {
        int error = 1;
 
        // Get the service assoicated to the consumer
-       mlt_service service = mlt_consumer_service( this );
+       mlt_service service = MLT_CONSUMER_SERVICE( self );
 
        if ( mlt_service_producer( service ) == NULL )
        {
                struct timeval now;
                struct timespec tm;
-               pthread_mutex_lock( &this->put_mutex );
-               while ( !mlt_consumer_is_stopped( this ) && this->put != NULL )
+               consumer_private *priv = self->local;
+
+               pthread_mutex_lock( &priv->put_mutex );
+               while ( priv->put_active && priv->put != NULL )
                {
                        gettimeofday( &now, NULL );
                        tm.tv_sec = now.tv_sec + 1;
                        tm.tv_nsec = now.tv_usec * 1000;
-                       pthread_cond_timedwait( &this->put_cond, &this->put_mutex, &tm );
+                       pthread_cond_timedwait( &priv->put_cond, &priv->put_mutex, &tm );
                }
-               if ( this->put == NULL )
-                       this->put = frame;
+               if ( priv->put_active && priv->put == NULL )
+                       priv->put = frame;
                else
                        mlt_frame_close( frame );
-               pthread_cond_broadcast( &this->put_cond );
-               pthread_mutex_unlock( &this->put_mutex );
+               pthread_cond_broadcast( &priv->put_cond );
+               pthread_mutex_unlock( &priv->put_mutex );
        }
        else
        {
@@ -236,36 +586,42 @@ int mlt_consumer_put_frame( mlt_consumer this, mlt_frame frame )
 }
 
 /** Protected method for consumer to get frames from connected service
-*/
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ * \return a frame
+ */
 
-mlt_frame mlt_consumer_get_frame( mlt_consumer this )
+mlt_frame mlt_consumer_get_frame( mlt_consumer self )
 {
        // Frame to return
        mlt_frame frame = NULL;
 
        // Get the service assoicated to the consumer
-       mlt_service service = mlt_consumer_service( this );
+       mlt_service service = MLT_CONSUMER_SERVICE( self );
 
        // Get the consumer properties
-       mlt_properties properties = mlt_consumer_properties( this );
+       mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
 
        // Get the frame
        if ( mlt_service_producer( service ) == NULL && mlt_properties_get_int( properties, "put_mode" ) )
        {
                struct timeval now;
                struct timespec tm;
-               pthread_mutex_lock( &this->put_mutex );
-               while ( !mlt_consumer_is_stopped( this ) && this->put == NULL )
+               consumer_private *priv = self->local;
+
+               pthread_mutex_lock( &priv->put_mutex );
+               while ( priv->put_active && priv->put == NULL )
                {
                        gettimeofday( &now, NULL );
                        tm.tv_sec = now.tv_sec + 1;
                        tm.tv_nsec = now.tv_usec * 1000;
-                       pthread_cond_timedwait( &this->put_cond, &this->put_mutex, &tm );
+                       pthread_cond_timedwait( &priv->put_cond, &priv->put_mutex, &tm );
                }
-               frame = this->put;
-               this->put = NULL;
-               pthread_cond_broadcast( &this->put_cond );
-               pthread_mutex_unlock( &this->put_mutex );
+               frame = priv->put;
+               priv->put = NULL;
+               pthread_cond_broadcast( &priv->put_cond );
+               pthread_mutex_unlock( &priv->put_mutex );
                if ( frame != NULL )
                        mlt_service_apply_filters( service, frame, 0 );
        }
@@ -273,11 +629,15 @@ mlt_frame mlt_consumer_get_frame( mlt_consumer this )
        {
                mlt_service_get_frame( service, &frame, 0 );
        }
+       else
+       {
+               frame = mlt_frame_init( service );
+       }
 
        if ( frame != NULL )
        {
                // Get the frame properties
-               mlt_properties frame_properties = mlt_frame_properties( frame );
+               mlt_properties frame_properties = MLT_FRAME_PROPERTIES( frame );
 
                // Get the test card producer
                mlt_producer test_card = mlt_properties_get_data( properties, "test_card_producer", NULL );
@@ -286,19 +646,25 @@ mlt_frame mlt_consumer_get_frame( mlt_consumer this )
                if ( test_card != NULL )
                        mlt_properties_set_data( frame_properties, "test_card_producer", test_card, 0, NULL, NULL );
 
-               // Attach the rescale property
+               // Pass along the interpolation and deinterlace options
+               // TODO: get rid of consumer_deinterlace and use profile.progressive
                mlt_properties_set( frame_properties, "rescale.interp", mlt_properties_get( properties, "rescale" ) );
-
-               // Aspect ratio and other jiggery pokery
-               mlt_properties_set_double( frame_properties, "consumer_aspect_ratio", mlt_properties_get_double( properties, "aspect_ratio" ) );
-               if ( mlt_properties_get_int( properties, "progressive" ) || mlt_properties_get_int( properties, "deinterlace" ) )
-                       mlt_properties_set_int( frame_properties, "consumer_deinterlace", 1 );
+               mlt_properties_set_int( frame_properties, "consumer_deinterlace", mlt_properties_get_int( properties, "progressive" ) | mlt_properties_get_int( properties, "deinterlace" ) );
+               mlt_properties_set( frame_properties, "deinterlace_method", mlt_properties_get( properties, "deinterlace_method" ) );
+               mlt_properties_set_int( frame_properties, "consumer_tff", mlt_properties_get_int( properties, "top_field_first" ) );
        }
 
        // Return the frame
        return frame;
 }
 
+/** Compute the time difference between now and a time value.
+ *
+ * \private \memberof mlt_consumer_s
+ * \param time1 a time value to be compared against now
+ * \return the difference in microseconds
+ */
+
 static inline long time_difference( struct timeval *time1 )
 {
        struct timeval time2;
@@ -308,13 +674,21 @@ static inline long time_difference( struct timeval *time1 )
        return time1->tv_sec * 1000000 + time1->tv_usec - time2.tv_sec * 1000000 - time2.tv_usec;
 }
 
+/** The thread procedure for asynchronously pulling frames through the service
+ * network connected to a consumer.
+ *
+ * \private \memberof mlt_consumer_s
+ * \param arg a consumer
+ */
+
 static void *consumer_read_ahead_thread( void *arg )
 {
        // The argument is the consumer
-       mlt_consumer this = arg;
+       mlt_consumer self = arg;
+       consumer_private *priv = self->local;
 
        // Get the properties of the consumer
-       mlt_properties properties = mlt_consumer_properties( this );
+       mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
 
        // Get the width and height
        int width = mlt_properties_get_int( properties, "width" );
@@ -322,15 +696,33 @@ static void *consumer_read_ahead_thread( void *arg )
 
        // See if video is turned off
        int video_off = mlt_properties_get_int( properties, "video_off" );
+       int preview_off = mlt_properties_get_int( properties, "preview_off" );
+       int preview_format = mlt_properties_get_int( properties, "preview_format" );
 
        // Get the audio settings
-       mlt_audio_format afmt = mlt_audio_pcm;
+       mlt_audio_format afmt = mlt_audio_s16;
+       const char *format = mlt_properties_get( properties, "mlt_audio_format" );
+       if ( format )
+       {
+               if ( !strcmp( format, "none" ) )
+                       afmt = mlt_audio_none;
+               else if ( !strcmp( format, "s32" ) )
+                       afmt = mlt_audio_s32;
+               else if ( !strcmp( format, "s32le" ) )
+                       afmt = mlt_audio_s32le;
+               else if ( !strcmp( format, "float" ) )
+                       afmt = mlt_audio_float;
+               else if ( !strcmp( format, "f32le" ) )
+                       afmt = mlt_audio_f32le;
+               else if ( !strcmp( format, "u8" ) )
+                       afmt = mlt_audio_u8;
+       }
        int counter = 0;
        double fps = mlt_properties_get_double( properties, "fps" );
        int channels = mlt_properties_get_int( properties, "channels" );
        int frequency = mlt_properties_get_int( properties, "frequency" );
        int samples = 0;
-       int16_t *pcm = NULL;
+       void *audio = NULL;
 
        // See if audio is turned off
        int audio_off = mlt_properties_get_int( properties, "audio_off" );
@@ -346,89 +738,119 @@ static void *consumer_read_ahead_thread( void *arg )
        struct timeval ante;
 
        // Average time for get_frame and get_image
-       int count = 1;
+       int count = 0;
        int skipped = 0;
-       int64_t time_wait = 0;
-       int64_t time_frame = 0;
        int64_t time_process = 0;
        int skip_next = 0;
+       mlt_position pos = 0;
+       mlt_position start_pos = 0;
+       mlt_position last_pos = 0;
+       int frame_duration = mlt_properties_get_int( properties, "frame_duration" );
+       int drop_max = mlt_properties_get_int( properties, "drop_max" );
 
-       // Get the first frame
-       frame = mlt_consumer_get_frame( this );
+       if ( preview_off && preview_format != 0 )
+               priv->format = preview_format;
 
-       // Get the image of the first frame
-       if ( !video_off )
-               mlt_frame_get_image( frame, &image, &this->format, &width, &height, 0 );
+       mlt_events_fire( properties, "consumer-thread-started", NULL );
 
-       if ( !audio_off )
+       // Get the first frame
+       frame = mlt_consumer_get_frame( self );
+
+       if ( frame )
        {
-               samples = mlt_sample_calculator( fps, frequency, counter++ );
-               mlt_frame_get_audio( frame, &pcm, &afmt, &frequency, &channels, &samples );
-               frame->get_audio = NULL;
-       }
+               // Get the image of the first frame
+               if ( !video_off )
+               {
+                       mlt_events_fire( MLT_CONSUMER_PROPERTIES( self ), "consumer-frame-render", frame, NULL );
+                       mlt_frame_get_image( frame, &image, &priv->format, &width, &height, 0 );
+               }
+
+               if ( !audio_off )
+               {
+                       samples = mlt_sample_calculator( fps, frequency, counter++ );
+                       mlt_frame_get_audio( frame, &audio, &afmt, &frequency, &channels, &samples );
+               }
 
-       mlt_properties_set_int( mlt_frame_properties( frame ), "rendered", 1 );
+               // Mark as rendered
+               mlt_properties_set_int( MLT_FRAME_PROPERTIES( frame ), "rendered", 1 );
+               last_pos = start_pos = pos = mlt_frame_get_position( frame );
+       }
 
        // Get the starting time (can ignore the times above)
        gettimeofday( &ante, NULL );
 
        // Continue to read ahead
-       while ( this->ahead )
+       while ( priv->ahead )
        {
                // Put the current frame into the queue
-               pthread_mutex_lock( &this->mutex );
-               while( this->ahead && mlt_deque_count( this->queue ) >= buffer )
-                       pthread_cond_wait( &this->cond, &this->mutex );
-               mlt_deque_push_back( this->queue, frame );
-               pthread_cond_broadcast( &this->cond );
-               pthread_mutex_unlock( &this->mutex );
-
-               time_wait += time_difference( &ante );
+               pthread_mutex_lock( &priv->queue_mutex );
+               while( priv->ahead && mlt_deque_count( priv->queue ) >= buffer )
+                       pthread_cond_wait( &priv->queue_cond, &priv->queue_mutex );
+               if ( priv->is_purge )
+               {
+                       mlt_frame_close( frame );
+                       priv->is_purge = 0;
+               }
+               else
+               {
+                       mlt_deque_push_back( priv->queue, frame );
+               }
+               pthread_cond_broadcast( &priv->queue_cond );
+               pthread_mutex_unlock( &priv->queue_mutex );
 
                // Get the next frame
-               frame = mlt_consumer_get_frame( this );
-               time_frame += time_difference( &ante );
+               frame = mlt_consumer_get_frame( self );
 
                // If there's no frame, we're probably stopped...
                if ( frame == NULL )
                        continue;
+               pos = mlt_frame_get_position( frame );
 
-               // Increment the count
+               // Increment the counter used for averaging processing cost
                count ++;
 
-               // All non normal playback frames should be shown
-               if ( mlt_properties_get_int( mlt_frame_properties( frame ), "_speed" ) != 1 )
+               // All non-normal playback frames should be shown
+               if ( mlt_properties_get_int( MLT_FRAME_PROPERTIES( frame ), "_speed" ) != 1 )
                {
-                       skipped = 0;
-                       time_frame = 0;
-                       time_process = 0;
-                       time_wait = 0;
-                       count = 1;
-                       skip_next = 0;
+#ifdef DEINTERLACE_ON_NOT_NORMAL_SPEED
+                       mlt_properties_set_int( MLT_FRAME_PROPERTIES( frame ), "consumer_deinterlace", 1 );
+#endif
+                       // Indicate seeking or trick-play
+                       start_pos = pos;
                }
 
-               // Get the image
-               if ( !skip_next )
+               // If skip flag not set or frame-dropping disabled
+               if ( !skip_next || priv->real_time == -1 )
                {
-                       // Get the image, mark as rendered and time it
                        if ( !video_off )
-                               mlt_frame_get_image( frame, &image, &this->format, &width, &height, 0 );
-                       mlt_properties_set_int( mlt_frame_properties( frame ), "rendered", 1 );
+                       {
+                               // Reset width/height - could have been changed by previous mlt_frame_get_image
+                               width = mlt_properties_get_int( properties, "width" );
+                               height = mlt_properties_get_int( properties, "height" );
+
+                               // Get the image
+                               mlt_events_fire( MLT_CONSUMER_PROPERTIES( self ), "consumer-frame-render", frame, NULL );
+                               mlt_frame_get_image( frame, &image, &priv->format, &width, &height, 0 );
+                       }
+
+                       // Indicate the rendered image is available.
+                       mlt_properties_set_int( MLT_FRAME_PROPERTIES( frame ), "rendered", 1 );
+
+                       // Reset consecutively-skipped counter
+                       skipped = 0;
                }
-               else
+               else // Skip image processing
                {
-                       // Increment the number of sequentially skipped frames
-                       skipped ++;
-                       skip_next = 0;
+                       // Increment the number of consecutively-skipped frames
+                       skipped++;
 
-                       // If we've reached an unacceptable level, reset everything
-                       if ( skipped > 5 )
+                       // If too many (1 sec) consecutively-skipped frames
+                       if ( skipped > drop_max )
                        {
-                               skipped = 0;
-                               time_frame = 0;
+                               // Reset cost tracker
                                time_process = 0;
-                               time_wait = 0;
                                count = 1;
+                               mlt_log_verbose( self, "too many frames dropped - forcing next frame\n" );
                        }
                }
 
@@ -436,221 +858,795 @@ static void *consumer_read_ahead_thread( void *arg )
                if ( !audio_off )
                {
                        samples = mlt_sample_calculator( fps, frequency, counter++ );
-                       mlt_frame_get_audio( frame, &pcm, &afmt, &frequency, &channels, &samples );
-                       frame->get_audio = NULL;
+                       mlt_frame_get_audio( frame, &audio, &afmt, &frequency, &channels, &samples );
+               }
+
+               // Get the time to process this frame
+               int64_t time_current = time_difference( &ante );
+
+               // If the current time is not suddenly some large amount
+               if ( time_current < time_process / count * 20 || !time_process || count < 5 )
+               {
+                       // Accumulate the cost for processing this frame
+                       time_process += time_current;
+               }
+               else
+               {
+                       mlt_log_debug( self, "current %"PRId64" threshold %"PRId64" count %d\n",
+                               time_current, (int64_t) (time_process / count * 20), count );
+                       // Ignore the cost of this frame's time
+                       count--;
                }
 
-               // Increment the time take for this frame
-               time_process += time_difference( &ante );
+               // Determine if we started, resumed, or seeked
+               if ( pos != last_pos + 1 )
+                       start_pos = pos;
+               last_pos = pos;
 
-               // Determine if the next frame should be skipped
-               if ( mlt_deque_count( this->queue ) <= 5 && ( ( time_wait + time_frame + time_process ) / count ) > 40000 )
-                       skip_next = 1;
+               // Do not skip the first 20% of buffer at start, resume, or seek
+               if ( pos - start_pos <= buffer / 5 + 1 )
+               {
+                       // Reset cost tracker
+                       time_process = 0;
+                       count = 1;
+               }
+
+               // Reset skip flag
+               skip_next = 0;
+
+               // Only consider skipping if the buffer level is low (or really small)
+               if ( mlt_deque_count( priv->queue ) <= buffer / 5 + 1 )
+               {
+                       // Skip next frame if average cost exceeds frame duration.
+                       if ( time_process / count > frame_duration )
+                               skip_next = 1;
+                       if ( skip_next )
+                               mlt_log_debug( self, "avg usec %"PRId64" (%"PRId64"/%d) duration %d\n",
+                                       time_process/count, time_process, count, frame_duration);
+               }
        }
 
        // Remove the last frame
        mlt_frame_close( frame );
+       mlt_events_fire( properties, "consumer-thread-stopped", NULL );
 
        return NULL;
 }
 
-static void consumer_read_ahead_start( mlt_consumer this )
+/** Locate the first unprocessed frame in the queue.
+ *
+ * When playing with realtime behavior, we do not use the true head, but
+ * rather an adjusted process_head. The process_head is adjusted based on
+ * the rate of frame-dropping or recovery from frame-dropping. The idea is
+ * that as the level of frame-dropping increases to move the process_head
+ * closer to the tail because the frames are not completing processing prior
+ * to their playout! Then, as frames are not dropped the process_head moves
+ * back closer to the head of the queue so that worker threads can work 
+ * ahead of the playout point (queue head).
+ *
+ * \private \memberof mlt_consumer_s
+ * \param self a consumer
+ * \return an index into the queue
+ */
+
+static inline int first_unprocessed_frame( mlt_consumer self )
 {
-       pthread_attr_t thread_attributes;
-       
+       consumer_private *priv = self->local;
+       int index = priv->real_time <= 0 ? 0 : priv->process_head;
+       while ( index < mlt_deque_count( priv->queue ) && MLT_FRAME( mlt_deque_peek( priv->queue, index ) )->is_processing )
+               index++;
+       return index;
+}
+
+/** The worker thread procedure for parallel processing frames.
+ *
+ * \private \memberof mlt_consumer_s
+ * \param arg a consumer
+ */
+
+static void *consumer_worker_thread( void *arg )
+{
+       // The argument is the consumer
+       mlt_consumer self = arg;
+       consumer_private *priv = self->local;
+
+       // Get the properties of the consumer
+       mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+
+       // Get the width and height
+       int width = mlt_properties_get_int( properties, "width" );
+       int height = mlt_properties_get_int( properties, "height" );
+       mlt_image_format format = priv->format;
+
+       // See if video is turned off
+       int video_off = mlt_properties_get_int( properties, "video_off" );
+       int preview_off = mlt_properties_get_int( properties, "preview_off" );
+       int preview_format = mlt_properties_get_int( properties, "preview_format" );
+
+       // General frame variable
+       mlt_frame frame = NULL;
+       uint8_t *image = NULL;
+
+       if ( preview_off && preview_format != 0 )
+               format = preview_format;
+
+       mlt_events_fire( properties, "consumer-thread-started", NULL );
+
+       // Continue to read ahead
+       while ( priv->ahead )
+       {
+               // Get the next unprocessed frame from the work queue
+               pthread_mutex_lock( &priv->queue_mutex );
+               int index = first_unprocessed_frame( self );
+               while ( priv->ahead && index >= mlt_deque_count( priv->queue ) )
+               {
+                       mlt_log_debug( MLT_CONSUMER_SERVICE(self), "waiting in worker index = %d queue count = %d\n",
+                               index, mlt_deque_count( priv->queue ) );
+                       pthread_cond_wait( &priv->queue_cond, &priv->queue_mutex );
+                       index = first_unprocessed_frame( self );
+               }
+
+               // Mark the frame for processing
+               frame = mlt_deque_peek( priv->queue, index );
+               if ( frame )
+               {
+                       mlt_log_debug( MLT_CONSUMER_SERVICE(self), "worker processing index = %d frame " MLT_POSITION_FMT " queue count = %d\n",
+                               index, mlt_frame_get_position(frame), mlt_deque_count( priv->queue ) );
+                       frame->is_processing = 1;
+                       mlt_properties_inc_ref( MLT_FRAME_PROPERTIES( frame ) );
+               }
+               pthread_mutex_unlock( &priv->queue_mutex );
+
+               // If there's no frame, we're probably stopped...
+               if ( frame == NULL )
+                       continue;
+
+#ifdef DEINTERLACE_ON_NOT_NORMAL_SPEED
+               // All non normal playback frames should be shown
+               if ( mlt_properties_get_int( MLT_FRAME_PROPERTIES( frame ), "_speed" ) != 1 )
+                       mlt_properties_set_int( MLT_FRAME_PROPERTIES( frame ), "consumer_deinterlace", 1 );
+#endif
+
+               // Get the image
+               if ( !video_off )
+               {
+                       // Fetch width/height again
+                       width = mlt_properties_get_int( properties, "width" );
+                       height = mlt_properties_get_int( properties, "height" );
+                       mlt_events_fire( MLT_CONSUMER_PROPERTIES( self ), "consumer-frame-render", frame, NULL );
+                       mlt_frame_get_image( frame, &image, &format, &width, &height, 0 );
+               }
+               mlt_properties_set_int( MLT_FRAME_PROPERTIES( frame ), "rendered", 1 );
+               mlt_frame_close( frame );
+
+               // Tell a waiting thread (non-realtime main consumer thread) that we are done.
+               pthread_mutex_lock( &priv->done_mutex );
+               pthread_cond_broadcast( &priv->done_cond );
+               pthread_mutex_unlock( &priv->done_mutex );
+       }
+       mlt_events_fire( properties, "consumer-thread-stopped", NULL );
+
+       return NULL;
+}
+
+/** Start the read/render thread.
+ *
+ * \private \memberof mlt_consumer_s
+ * \param self a consumer
+ */
+
+static void consumer_read_ahead_start( mlt_consumer self )
+{
+       consumer_private *priv = self->local;
+
        // We're running now
-       this->ahead = 1;
+       priv->ahead = 1;
 
        // Create the frame queue
-       this->queue = mlt_deque_init( );
+       priv->queue = mlt_deque_init( );
 
-       // Create the mutex
-       pthread_mutex_init( &this->mutex, NULL );
+       // Create the queue mutex
+       pthread_mutex_init( &priv->queue_mutex, NULL );
 
        // Create the condition
-       pthread_cond_init( &this->cond, NULL );
+       pthread_cond_init( &priv->queue_cond, NULL );
+
+       // Create the read ahead
+       if ( mlt_properties_get( MLT_CONSUMER_PROPERTIES( self ), "priority" ) )
+       {
+               struct sched_param priority;
+               priority.sched_priority = mlt_properties_get_int( MLT_CONSUMER_PROPERTIES( self ), "priority" );
+               pthread_attr_t thread_attributes;
+               pthread_attr_init( &thread_attributes );
+               pthread_attr_setschedpolicy( &thread_attributes, SCHED_OTHER );
+               pthread_attr_setschedparam( &thread_attributes, &priority );
+               pthread_attr_setinheritsched( &thread_attributes, PTHREAD_EXPLICIT_SCHED );
+               pthread_attr_setscope( &thread_attributes, PTHREAD_SCOPE_SYSTEM );
+               if ( pthread_create( &priv->ahead_thread, &thread_attributes, consumer_read_ahead_thread, self ) < 0 )
+                       pthread_create( &priv->ahead_thread, NULL, consumer_read_ahead_thread, self );
+               pthread_attr_destroy( &thread_attributes );
+       }
+       else
+       {
+               pthread_create( &priv->ahead_thread, NULL, consumer_read_ahead_thread, self );
+       }
+       priv->started = 1;
+}
 
-       // Inherit the scheduling priority
-       pthread_attr_init( &thread_attributes );
-       pthread_attr_setinheritsched( &thread_attributes, PTHREAD_INHERIT_SCHED );
+/** Start the worker threads.
+ *
+ * \private \memberof mlt_consumer_s
+ * \param self a consumer
+ */
+
+static void consumer_work_start( mlt_consumer self )
+{
+       consumer_private *priv = self->local;
+       int n = abs( priv->real_time );
+       pthread_t *thread = calloc( 1, sizeof( pthread_t ) * n );
+
+       // We're running now
+       priv->ahead = 1;
+       priv->threads = thread;
+       
+       // These keep track of the accelleration of frame dropping or recovery.
+       priv->consecutive_dropped = 0;
+       priv->consecutive_rendered = 0;
        
-       // Create the read ahead 
-       pthread_create( &this->ahead_thread, &thread_attributes, consumer_read_ahead_thread, this );
+       // This is the position in the queue from which to look for a frame to process.
+       // If we always start from the head, then we may likely not complete processing
+       // before the frame is played out.
+       priv->process_head = 0;
+
+       // Create the queues
+       priv->queue = mlt_deque_init();
+       priv->worker_threads = mlt_deque_init();
+
+       // Create the mutexes
+       pthread_mutex_init( &priv->queue_mutex, NULL );
+       pthread_mutex_init( &priv->done_mutex, NULL );
+
+       // Create the conditions
+       pthread_cond_init( &priv->queue_cond, NULL );
+       pthread_cond_init( &priv->done_cond, NULL );
+
+       // Create the read ahead
+       if ( mlt_properties_get( MLT_CONSUMER_PROPERTIES( self ), "priority" ) )
+       {
+
+               struct sched_param priority;
+               pthread_attr_t thread_attributes;
+
+               priority.sched_priority = mlt_properties_get_int( MLT_CONSUMER_PROPERTIES( self ), "priority" );
+               pthread_attr_init( &thread_attributes );
+               pthread_attr_setschedpolicy( &thread_attributes, SCHED_OTHER );
+               pthread_attr_setschedparam( &thread_attributes, &priority );
+               pthread_attr_setinheritsched( &thread_attributes, PTHREAD_EXPLICIT_SCHED );
+               pthread_attr_setscope( &thread_attributes, PTHREAD_SCOPE_SYSTEM );
+
+               while ( n-- )
+               {
+                       if ( pthread_create( thread, &thread_attributes, consumer_worker_thread, self ) < 0 )
+                               if ( pthread_create( thread, NULL, consumer_worker_thread, self ) == 0 )
+                                       mlt_deque_push_back( priv->worker_threads, thread );
+                       thread++;
+               }
+               pthread_attr_destroy( &thread_attributes );
+       }
+
+       else
+       {
+               while ( n-- )
+               {
+                       if ( pthread_create( thread, NULL, consumer_worker_thread, self ) == 0 )
+                               mlt_deque_push_back( priv->worker_threads, thread );
+                       thread++;
+               }
+       }
+       priv->started = 1;
 }
 
-static void consumer_read_ahead_stop( mlt_consumer this )
+/** Stop the read/render thread.
+ *
+ * \private \memberof mlt_consumer_s
+ * \param self a consumer
+ */
+
+static void consumer_read_ahead_stop( mlt_consumer self )
 {
+       consumer_private *priv = self->local;
+
        // Make sure we're running
-       if ( this->ahead )
+// TODO improve support for atomic ops in general (see libavutil/atomic.h)
+#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
+       if ( __sync_val_compare_and_swap( &priv->started, 1, 0 ) )
        {
+#else
+       if ( priv->started )
+       {
+               priv->started = 0;
+#endif
                // Inform thread to stop
-               this->ahead = 0;
+               priv->ahead = 0;
 
                // Broadcast to the condition in case it's waiting
-               pthread_mutex_lock( &this->mutex );
-               pthread_cond_broadcast( &this->cond );
-               pthread_mutex_unlock( &this->mutex );
+               pthread_mutex_lock( &priv->queue_mutex );
+               pthread_cond_broadcast( &priv->queue_cond );
+               pthread_mutex_unlock( &priv->queue_mutex );
 
                // Broadcast to the put condition in case it's waiting
-               pthread_mutex_lock( &this->put_mutex );
-               pthread_cond_broadcast( &this->put_cond );
-               pthread_mutex_unlock( &this->put_mutex );
+               pthread_mutex_lock( &priv->put_mutex );
+               pthread_cond_broadcast( &priv->put_cond );
+               pthread_mutex_unlock( &priv->put_mutex );
 
                // Join the thread
-               pthread_join( this->ahead_thread, NULL );
+               pthread_join( priv->ahead_thread, NULL );
 
-               // Destroy the mutex
-               pthread_mutex_destroy( &this->mutex );
+               // Destroy the frame queue mutex
+               pthread_mutex_destroy( &priv->queue_mutex );
 
                // Destroy the condition
-               pthread_cond_destroy( &this->cond );
+               pthread_cond_destroy( &priv->queue_cond );
 
                // Wipe the queue
-               while ( mlt_deque_count( this->queue ) )
-                       mlt_frame_close( mlt_deque_pop_back( this->queue ) );
+               while ( mlt_deque_count( priv->queue ) )
+                       mlt_frame_close( mlt_deque_pop_back( priv->queue ) );
 
                // Close the queue
-               mlt_deque_close( this->queue );
+               mlt_deque_close( priv->queue );
        }
 }
 
-void mlt_consumer_purge( mlt_consumer this )
+/** Stop the worker threads.
+ *
+ * \private \memberof mlt_consumer_s
+ * \param self a consumer
+ */
+
+static void consumer_work_stop( mlt_consumer self )
 {
-       if ( this->ahead )
+       consumer_private *priv = self->local;
+
+       // Make sure we're running
+#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
+       if ( __sync_val_compare_and_swap( &priv->started, 1, 0 ) )
+       {
+#else
+       if ( priv->started )
        {
-               pthread_mutex_lock( &this->mutex );
-               while ( mlt_deque_count( this->queue ) )
-                       mlt_frame_close( mlt_deque_pop_back( this->queue ) );
-               pthread_cond_broadcast( &this->cond );
-               pthread_mutex_unlock( &this->mutex );
+               priv->started = 0;
+#endif
+               // Inform thread to stop
+               priv->ahead = 0;
+
+               // Broadcast to the queue condition in case it's waiting
+               pthread_mutex_lock( &priv->queue_mutex );
+               pthread_cond_broadcast( &priv->queue_cond );
+               pthread_mutex_unlock( &priv->queue_mutex );
+
+               // Broadcast to the put condition in case it's waiting
+               pthread_mutex_lock( &priv->put_mutex );
+               pthread_cond_broadcast( &priv->put_cond );
+               pthread_mutex_unlock( &priv->put_mutex );
+
+               // Broadcast to the done condition in case it's waiting
+               pthread_mutex_lock( &priv->done_mutex );
+               pthread_cond_broadcast( &priv->done_cond );
+               pthread_mutex_unlock( &priv->done_mutex );
+
+               // Join the threads
+               pthread_t *thread;
+               while ( ( thread = mlt_deque_pop_back( priv->worker_threads ) ) )
+                       pthread_join( *thread, NULL );
+
+               // Deallocate the array of threads
+               if ( priv->threads )
+                       free( priv->threads );
+
+               // Destroy the mutexes
+               pthread_mutex_destroy( &priv->queue_mutex );
+               pthread_mutex_destroy( &priv->done_mutex );
+
+               // Destroy the conditions
+               pthread_cond_destroy( &priv->queue_cond );
+               pthread_cond_destroy( &priv->done_cond );
+
+               // Wipe the queues
+               while ( mlt_deque_count( priv->queue ) )
+                       mlt_frame_close( mlt_deque_pop_back( priv->queue ) );
+
+               // Close the queues
+               mlt_deque_close( priv->queue );
+               mlt_deque_close( priv->worker_threads );
        }
 }
 
-mlt_frame mlt_consumer_rt_frame( mlt_consumer this )
+/** Flush the read/render thread's buffer.
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ */
+
+void mlt_consumer_purge( mlt_consumer self )
+{
+       if ( self )
+       {
+               consumer_private *priv = self->local;
+
+               pthread_mutex_lock( &priv->put_mutex );
+               if ( priv->put ) {
+                       mlt_frame_close( priv->put );
+                       priv->put = NULL;
+               }
+               pthread_cond_broadcast( &priv->put_cond );
+               pthread_mutex_unlock( &priv->put_mutex );
+
+               if ( priv->started && priv->real_time )
+                       pthread_mutex_lock( &priv->queue_mutex );
+
+               if ( self->purge )
+                       self->purge( self );
+
+               while ( priv->started && mlt_deque_count( priv->queue ) )
+                       mlt_frame_close( mlt_deque_pop_back( priv->queue ) );
+               if ( priv->started && priv->real_time )
+               {
+                       priv->is_purge = 1;
+                       pthread_cond_broadcast( &priv->queue_cond );
+                       pthread_mutex_unlock( &priv->queue_mutex );
+                       if ( abs( priv->real_time ) > 1 )
+                       {
+                               pthread_mutex_lock( &priv->done_mutex );
+                               pthread_cond_broadcast( &priv->done_cond );
+                               pthread_mutex_unlock( &priv->done_mutex );
+                       }
+               }
+
+               pthread_mutex_lock( &priv->put_mutex );
+               if ( priv->put ) {
+                       mlt_frame_close( priv->put );
+                       priv->put = NULL;
+               }
+               pthread_cond_broadcast( &priv->put_cond );
+               pthread_mutex_unlock( &priv->put_mutex );
+       }
+}
+
+/** Use multiple worker threads and a work queue.
+ */
+
+static mlt_frame worker_get_frame( mlt_consumer self, mlt_properties properties )
+{
+       // Frame to return
+       mlt_frame frame = NULL;
+       consumer_private *priv = self->local;
+       double fps = mlt_properties_get_double( properties, "fps" );
+       int threads = abs( priv->real_time );
+       int buffer = mlt_properties_get_int( properties, "_buffer" );
+       buffer = buffer > 0 ? buffer : mlt_properties_get_int( properties, "buffer" );
+       // This is a heuristic to determine a suitable minimum buffer size for the number of threads.
+       int headroom = 2 + threads * threads;
+       buffer = buffer < headroom ? headroom : buffer;
+
+       // Start worker threads if not already started.
+       if ( ! priv->ahead )
+       {
+               int prefill = mlt_properties_get_int( properties, "prefill" );
+               prefill = prefill > 0 && prefill < buffer ? prefill : buffer;
+
+               consumer_work_start( self );
+
+               // Fill the work queue.
+               int i = buffer;
+               while ( priv->ahead && i-- )
+               {
+                       frame = mlt_consumer_get_frame( self );
+                       if ( frame )
+                       {
+                               pthread_mutex_lock( &priv->queue_mutex );
+                               mlt_deque_push_back( priv->queue, frame );
+                               pthread_cond_signal( &priv->queue_cond );
+                               pthread_mutex_unlock( &priv->queue_mutex );
+                       }
+               }
+
+               // Wait for prefill
+               while ( priv->ahead && first_unprocessed_frame( self ) < prefill )
+               {
+                       pthread_mutex_lock( &priv->done_mutex );
+                       pthread_cond_wait( &priv->done_cond, &priv->done_mutex );
+                       pthread_mutex_unlock( &priv->done_mutex );
+               }
+               priv->process_head = threads;
+       }
+
+//     mlt_log_verbose( MLT_CONSUMER_SERVICE(self), "size %d done count %d work count %d process_head %d\n",
+//             threads, first_unprocessed_frame( self ), mlt_deque_count( priv->queue ), priv->process_head );
+
+       // Feed the work queue
+       while ( priv->ahead && mlt_deque_count( priv->queue ) < buffer )
+       {
+               frame = mlt_consumer_get_frame( self );
+               if ( frame )
+               {
+                       pthread_mutex_lock( &priv->queue_mutex );
+                       mlt_deque_push_back( priv->queue, frame );
+                       pthread_cond_signal( &priv->queue_cond );
+                       pthread_mutex_unlock( &priv->queue_mutex );
+               }
+       }
+
+       // Wait if not realtime.
+       while ( priv->ahead && priv->real_time < 0 && !priv->is_purge &&
+               !( mlt_properties_get_int( MLT_FRAME_PROPERTIES( MLT_FRAME( mlt_deque_peek_front( priv->queue ) ) ), "rendered" ) ) )
+       {
+               pthread_mutex_lock( &priv->done_mutex );
+               pthread_cond_wait( &priv->done_cond, &priv->done_mutex );
+               pthread_mutex_unlock( &priv->done_mutex );
+       }
+
+       // Get the frame from the queue.
+       pthread_mutex_lock( &priv->queue_mutex );
+       frame = mlt_deque_pop_front( priv->queue );
+       pthread_mutex_unlock( &priv->queue_mutex );
+       if ( ! frame ) {
+               priv->is_purge = 0;
+               return frame;
+       }
+
+       // Adapt the worker process head to the runtime conditions.
+       if ( priv->real_time > 0 )
+       {
+               if ( mlt_properties_get_int( MLT_FRAME_PROPERTIES( frame ), "rendered" ) )
+               {
+                       priv->consecutive_dropped = 0;
+                       if ( priv->process_head > threads && priv->consecutive_rendered >= priv->process_head )
+                               priv->process_head--;
+                       else
+                               priv->consecutive_rendered++;
+               }
+               else
+               {
+                       priv->consecutive_rendered = 0;
+                       if ( priv->process_head < buffer - threads && priv->consecutive_dropped > threads )
+                               priv->process_head++;
+                       else
+                               priv->consecutive_dropped++;
+               }
+//             mlt_log_verbose( MLT_CONSUMER_SERVICE(self), "dropped %d rendered %d process_head %d\n",
+//                     priv->consecutive_dropped, priv->consecutive_rendered, priv->process_head );
+
+               // Check for too many consecutively dropped frames
+               if ( priv->consecutive_dropped > mlt_properties_get_int( properties, "drop_max" ) )
+               {
+                       int orig_buffer = mlt_properties_get_int( properties, "buffer" );
+                       int prefill = mlt_properties_get_int( properties, "prefill" );
+                       mlt_log_verbose( self, "too many frames dropped - " );
+
+                       // If using a default low-latency buffer level (SDL) and below the limit
+                       if ( ( orig_buffer == 1 || prefill == 1 ) && buffer < (threads + 1) * 10 )
+                       {
+                               // Auto-scale the buffer to compensate
+                               mlt_log_verbose( self, "increasing buffer to %d\n", buffer + threads );
+                               mlt_properties_set_int( properties, "_buffer", buffer + threads );
+                               priv->consecutive_dropped = fps / 2;
+                       }
+                       else
+                       {
+                               // Tell the consumer to render it
+                               mlt_log_verbose( self, "forcing next frame\n" );
+                               mlt_properties_set_int( MLT_FRAME_PROPERTIES( frame ), "rendered", 1 );
+                               priv->consecutive_dropped = 0;
+                       }
+               }
+       }
+       if ( priv->is_purge ) {
+               priv->is_purge = 0;
+               mlt_frame_close( frame );
+               frame = NULL;
+       }
+       return frame;
+}
+
+/** Get the next frame from the producer connected to a consumer.
+ *
+ * Typically, one uses this instead of \p mlt_consumer_get_frame to make
+ * the asynchronous/real-time behavior configurable at runtime.
+ * You should close the frame returned from this when you are done with it.
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ * \return a frame
+ */
+
+mlt_frame mlt_consumer_rt_frame( mlt_consumer self )
 {
        // Frame to return
        mlt_frame frame = NULL;
 
        // Get the properties
-       mlt_properties properties = mlt_consumer_properties( this );
+       mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+       consumer_private *priv = self->local;
 
        // Check if the user has requested real time or not
-       if ( this->real_time )
+       if ( priv->real_time > 1 || priv->real_time < -1 )
+       {
+               // see above
+               return worker_get_frame( self, properties );
+       }
+       else if ( priv->real_time == 1 || priv->real_time == -1 )
        {
                int size = 1;
 
                // Is the read ahead running?
-               if ( this->ahead == 0 )
+               if ( priv->ahead == 0 )
                {
                        int buffer = mlt_properties_get_int( properties, "buffer" );
                        int prefill = mlt_properties_get_int( properties, "prefill" );
-                       consumer_read_ahead_start( this );
+                       consumer_read_ahead_start( self );
                        if ( buffer > 1 )
                                size = prefill > 0 && prefill < buffer ? prefill : buffer;
                }
-       
+
                // Get frame from queue
-               pthread_mutex_lock( &this->mutex );
-               while( this->ahead && mlt_deque_count( this->queue ) < size )
-                       pthread_cond_wait( &this->cond, &this->mutex );
-               frame = mlt_deque_pop_front( this->queue );
-               pthread_cond_broadcast( &this->cond );
-               pthread_mutex_unlock( &this->mutex );
+               pthread_mutex_lock( &priv->queue_mutex );
+               while( priv->ahead && mlt_deque_count( priv->queue ) < size )
+                       pthread_cond_wait( &priv->queue_cond, &priv->queue_mutex );
+               frame = mlt_deque_pop_front( priv->queue );
+               pthread_cond_broadcast( &priv->queue_cond );
+               pthread_mutex_unlock( &priv->queue_mutex );
        }
-       else
+       else // real_time == 0
        {
+               if ( !priv->ahead )
+               {
+                       priv->ahead = 1;
+                       mlt_events_fire( properties, "consumer-thread-started", NULL );
+               }
                // Get the frame in non real time
-               frame = mlt_consumer_get_frame( this );
+               frame = mlt_consumer_get_frame( self );
 
                // This isn't true, but from the consumers perspective it is
                if ( frame != NULL )
-                       mlt_properties_set_int( mlt_frame_properties( frame ), "rendered", 1 );
+                       mlt_properties_set_int( MLT_FRAME_PROPERTIES( frame ), "rendered", 1 );
        }
 
        return frame;
 }
 
 /** Callback for the implementation to indicate a stopped condition.
-*/
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ */
 
-void mlt_consumer_stopped( mlt_consumer this )
+void mlt_consumer_stopped( mlt_consumer self )
 {
-       mlt_properties_set_int( mlt_consumer_properties( this ), "running", 0 );
-       mlt_events_fire( mlt_consumer_properties( this ), "consumer-stopped", NULL );
+       mlt_properties_set_int( MLT_CONSUMER_PROPERTIES( self ), "running", 0 );
+       mlt_events_fire( MLT_CONSUMER_PROPERTIES( self ), "consumer-stopped", NULL );
+       mlt_event_unblock( ( ( consumer_private* ) self->local )->event_listener );
 }
 
 /** Stop the consumer.
-*/
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ * \return true if there was an error
+ */
 
-int mlt_consumer_stop( mlt_consumer this )
+int mlt_consumer_stop( mlt_consumer self )
 {
        // Get the properies
-       mlt_properties properties = mlt_consumer_properties( this );
+       mlt_properties properties = MLT_CONSUMER_PROPERTIES( self );
+       consumer_private *priv = self->local;
+
+       // Just in case...
+       mlt_log( MLT_CONSUMER_SERVICE( self ), MLT_LOG_DEBUG, "stopping put waiting\n" );
+       pthread_mutex_lock( &priv->put_mutex );
+       priv->put_active = 0;
+       pthread_cond_broadcast( &priv->put_cond );
+       pthread_mutex_unlock( &priv->put_mutex );
 
        // Stop the consumer
-       if ( this->stop != NULL )
-               this->stop( this );
+       mlt_log( MLT_CONSUMER_SERVICE( self ), MLT_LOG_DEBUG, "stopping consumer\n" );
+       
+       // Cancel the read ahead threads
+       priv->ahead = 0;
+       if ( priv->started )
+       {
+               // Unblock the consumer calling mlt_consumer_rt_frame
+               pthread_mutex_lock( &priv->queue_mutex );
+               pthread_cond_broadcast( &priv->queue_cond );
+               pthread_mutex_unlock( &priv->queue_mutex );
+       }
+       
+       // Invoke the child callback
+       if ( self->stop != NULL )
+               self->stop( self );
 
        // Check if the user has requested real time or not and stop if necessary
-       if ( mlt_properties_get_int( properties, "real_time" ) )
-               consumer_read_ahead_stop( this );
-
-       // Just in case...
-       pthread_mutex_lock( &this->put_mutex );
-       pthread_cond_broadcast( &this->put_cond );
-       pthread_mutex_unlock( &this->put_mutex );
+       mlt_log( MLT_CONSUMER_SERVICE( self ), MLT_LOG_DEBUG, "stopping read_ahead\n" );
+       if ( abs( priv->real_time ) == 1 )
+               consumer_read_ahead_stop( self );
+       else if ( abs( priv->real_time ) > 1 )
+               consumer_work_stop( self );
 
        // Kill the test card
        mlt_properties_set_data( properties, "test_card_producer", NULL, 0, NULL, NULL );
 
        // Check and run a post command
        if ( mlt_properties_get( properties, "post" ) )
-               system( mlt_properties_get( properties, "post" ) );
+               if (system( mlt_properties_get( properties, "post" ) ) == -1 )
+                       mlt_log( MLT_CONSUMER_SERVICE( self ), MLT_LOG_ERROR, "system(%s) failed!\n", mlt_properties_get( properties, "post" ) );
 
-       if ( this->put != NULL )
-       {
-               mlt_frame_close( this->put );
-               this->put = NULL;
-       }
+       mlt_log( MLT_CONSUMER_SERVICE( self ), MLT_LOG_DEBUG, "stopped\n" );
 
        return 0;
 }
 
 /** Determine if the consumer is stopped.
-*/
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ * \return true if the consumer is stopped
+ */
 
-int mlt_consumer_is_stopped( mlt_consumer this )
+int mlt_consumer_is_stopped( mlt_consumer self )
 {
        // Check if the consumer is stopped
-       if ( this->is_stopped != NULL )
-               return this->is_stopped( this );
+       if ( self && self->is_stopped )
+               return self->is_stopped( self );
 
        return 0;
 }
 
-/** Close the consumer.
-*/
+/** Close and destroy the consumer.
+ *
+ * \public \memberof mlt_consumer_s
+ * \param self a consumer
+ */
 
-void mlt_consumer_close( mlt_consumer this )
+void mlt_consumer_close( mlt_consumer self )
 {
-       if ( this != NULL && mlt_properties_dec_ref( mlt_consumer_properties( this ) ) <= 0 )
+       if ( self != NULL && mlt_properties_dec_ref( MLT_CONSUMER_PROPERTIES( self ) ) <= 0 )
        {
                // Get the childs close function
-               void ( *consumer_close )( ) = this->close;
-
-               // Make sure it only gets called once
-               this->close = NULL;
-               this->parent.close = NULL;
+               void ( *consumer_close )( ) = self->close;
 
-               // Destroy the push mutex and condition
-               pthread_cond_broadcast( &this->put_cond );
-               pthread_mutex_destroy( &this->put_mutex );
-               pthread_cond_destroy( &this->put_cond );
+               if ( consumer_close )
+               {
+                       // Just in case...
+                       //mlt_consumer_stop( self );
 
-               // Call the childs close if available
-               if ( consumer_close != NULL )
-                       consumer_close( this );
+                       self->close = NULL;
+                       consumer_close( self );
+               }
                else
-                       mlt_service_close( &this->parent );
+               {
+                       consumer_private *priv = self->local;
+
+                       // Make sure it only gets called once
+                       self->parent.close = NULL;
+
+                       // Destroy the push mutex and condition
+                       pthread_mutex_destroy( &priv->put_mutex );
+                       pthread_cond_destroy( &priv->put_cond );
+
+                       mlt_service_close( &self->parent );
+                       free( priv );
+               }
        }
 }
+
+/** Get the position of the last frame shown.
+ *
+ * \public \memberof mlt_consumer_s
+ * \param consumer a consumer
+ * \return the position
+ */
+
+mlt_position mlt_consumer_position( mlt_consumer consumer )
+{
+       return ( ( consumer_private* ) consumer->local )->position;
+}
+