[mlt] / src / framework / mlt_producer.c

/**
 * \file mlt_producer.c
 * \brief abstraction for all producer services
 * \see mlt_producer_s
 *
 * Copyright (C) 2003-2009 Ushodaya Enterprises Limited
 * \author Charles Yates <charles.yates@pandora.be>
 *
 * 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
 * Lesser General Public License for more details.
 *
 * 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 "mlt_producer.h"
#include "mlt_factory.h"
#include "mlt_frame.h"
#include "mlt_parser.h"
#include "mlt_profile.h"
#include "mlt_log.h"

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

/* Forward references. */

static int producer_get_frame( mlt_service this, mlt_frame_ptr frame, int index );
static void mlt_producer_property_changed( mlt_service owner, mlt_producer this, char *name );
static void mlt_producer_service_changed( mlt_service owner, mlt_producer this );

/* for debugging */
//#define _MLT_PRODUCER_CHECKS_ 1
#ifdef _MLT_PRODUCER_CHECKS_
static int producers_created = 0;
static int producers_destroyed = 0;
#endif

/** Initialize a producer service.
 *
 * \public \memberof mlt_producer_s
 * \param this the producer structure to initialize
 * \param child a pointer to the child object for the subclass
 * \return true if there was an error
 */

int mlt_producer_init( mlt_producer this, void *child )
{
        // Check that we haven't received NULL
        int error = this == NULL;

        // Continue if no error
        if ( error == 0 )
        {
#ifdef _MLT_PRODUCER_CHECKS_
                producers_created ++;
#endif

                // Initialise the producer
                memset( this, 0, sizeof( struct mlt_producer_s ) );

                // Associate with the child
                this->child = child;

                // Initialise the service
                if ( mlt_service_init( &this->parent, this ) == 0 )
                {
                        // The parent is the service
                        mlt_service parent = &this->parent;

                        // Define the parent close
                        parent->close = ( mlt_destructor )mlt_producer_close;
                        parent->close_object = this;

                        // For convenience, we'll assume the close_object is this
                        this->close_object = this;

                        // Get the properties of the parent
                        mlt_properties properties = MLT_SERVICE_PROPERTIES( parent );

                        // Set the default properties
                        mlt_properties_set( properties, "mlt_type", "mlt_producer" );
                        mlt_properties_set_position( properties, "_position", 0.0 );
                        mlt_properties_set_double( properties, "_frame", 0 );
                        mlt_properties_set_double( properties, "_speed", 1.0 );
                        mlt_properties_set_position( properties, "in", 0 );
                        mlt_properties_set_position( properties, "out", 14999 );
                        mlt_properties_set_position( properties, "length", 15000 );
                        mlt_properties_set( properties, "eof", "pause" );
                        mlt_properties_set( properties, "resource", "<producer>" );

                        // Override service get_frame
                        parent->get_frame = producer_get_frame;

                        mlt_events_listen( properties, this, "service-changed", ( mlt_listener )mlt_producer_service_changed );
                        mlt_events_listen( properties, this, "property-changed", ( mlt_listener )mlt_producer_property_changed );
                        mlt_events_register( properties, "producer-changed", NULL );
                }
        }

        return error;
}

/** Listener for property changes.
 *
 * If the in, out, or length properties changed, fire a "producer-changed" event.
 *
 * \private \memberof mlt_producer_s
 * \param owner a service (ignored)
 * \param this the producer
 * \param name the property that changed
 */

static void mlt_producer_property_changed( mlt_service owner, mlt_producer this, char *name )
{
        if ( !strcmp( name, "in" ) || !strcmp( name, "out" ) || !strcmp( name, "length" ) )
                mlt_events_fire( MLT_PRODUCER_PROPERTIES( mlt_producer_cut_parent( this ) ), "producer-changed", NULL );
}

/** Listener for service changes.
 *
 * Fires the "producer-changed" event.
 *
 * \private \memberof mlt_producer_s
 * \param owner a service (ignored)
 * \param this the producer
 */

static void mlt_producer_service_changed( mlt_service owner, mlt_producer this )
{
        mlt_events_fire( MLT_PRODUCER_PROPERTIES( mlt_producer_cut_parent( this ) ), "producer-changed", NULL );
}

/** Create and initialize a new producer.
 *
 * \public \memberof mlt_producer_s
 * \return the new producer
 */

mlt_producer mlt_producer_new( mlt_profile profile )
{
        mlt_producer this = malloc( sizeof( struct mlt_producer_s ) );
        if ( this )
        {
                if ( mlt_producer_init( this, NULL ) == 0 )
                {
                        mlt_properties_set_data( MLT_PRODUCER_PROPERTIES( this ), "_profile", profile, 0, NULL, NULL );
                        mlt_properties_set_double( MLT_PRODUCER_PROPERTIES( this ), "aspect_ratio", mlt_profile_sar( profile ) );
                }
        }
        return this;
}

/** Determine if producer is a cut.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return true if \p this is a "cut" producer
 * \see mlt_producer_cut
 */

int mlt_producer_is_cut( mlt_producer this )
{
        return mlt_properties_get_int( MLT_PRODUCER_PROPERTIES( this ), "_cut" );
}

/** Determine if producer is a mix.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return true if this is a "mix" producer
 * \todo Define a mix producer.
 */

int mlt_producer_is_mix( mlt_producer this )
{
        mlt_properties properties = this != NULL ? MLT_PRODUCER_PROPERTIES( this ) : NULL;
        mlt_tractor tractor = properties != NULL ? mlt_properties_get_data( properties, "mlt_mix", NULL ) : NULL;
        return tractor != NULL;
}

/** Determine if the producer is a blank.
 *
 * Blank producers should only appear as an item in a playlist.
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return true if this is a "blank" producer
 * \see mlt_playlist_insert_blank
 */

int mlt_producer_is_blank( mlt_producer this )
{
        return this == NULL || !strcmp( mlt_properties_get( MLT_PRODUCER_PROPERTIES( mlt_producer_cut_parent( this ) ), "resource" ), "blank" );
}

/** Obtain the parent producer.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return either the parent producer if this is a "cut" producer or \p this otherwise.
 */

mlt_producer mlt_producer_cut_parent( mlt_producer this )
{
        mlt_properties properties = MLT_PRODUCER_PROPERTIES( this );
        if ( mlt_producer_is_cut( this ) )
                return mlt_properties_get_data( properties, "_cut_parent", NULL );
        else
                return this;
}

/** Create a cut of this producer.
 *
 * A "cut" is a portion of another (parent) producer.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \param in the beginning
 * \param out the end
 * \return the new producer
 * \todo Expand on the value of a cut.
 */

mlt_producer mlt_producer_cut( mlt_producer this, int in, int out )
{
        mlt_producer result = mlt_producer_new( mlt_service_profile( MLT_PRODUCER_SERVICE( this ) ) );
        mlt_producer parent = mlt_producer_cut_parent( this );
        mlt_properties properties = MLT_PRODUCER_PROPERTIES( result );
        mlt_properties parent_props = MLT_PRODUCER_PROPERTIES( parent );

        mlt_events_block( MLT_PRODUCER_PROPERTIES( result ), MLT_PRODUCER_PROPERTIES( result ) );
        // Special case - allow for a cut of the entire producer (this will squeeze all other cuts to 0)
        if ( in <= 0 )
                in = 0;
        if ( ( out < 0 || out >= mlt_producer_get_length( parent ) ) && !mlt_producer_is_blank( this ) )
                out = mlt_producer_get_length( parent ) - 1;

        mlt_properties_inc_ref( parent_props );
        mlt_properties_set_int( properties, "_cut", 1 );
        mlt_properties_set_data( properties, "_cut_parent", parent, 0, ( mlt_destructor )mlt_producer_close, NULL );
        mlt_properties_set_position( properties, "length", mlt_properties_get_position( parent_props, "length" ) );
        mlt_properties_set_double( properties, "aspect_ratio", mlt_properties_get_double( parent_props, "aspect_ratio" ) );
        mlt_producer_set_in_and_out( result, in, out );

        return result;
}

/** Get the parent service object.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return the service parent class
 * \see MLT_PRODUCER_SERVICE
 */

mlt_service mlt_producer_service( mlt_producer this )
{
        return this != NULL ? &this->parent : NULL;
}

/** Get the producer properties.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return the producer's property list
 * \see MLT_PRODUCER_PROPERTIES
 */

mlt_properties mlt_producer_properties( mlt_producer this )
{
        return MLT_SERVICE_PROPERTIES( &this->parent );
}

/** Seek to a specified position.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \param position set the "play head" position of the producer
 * \return false
 * \todo Document how the properties affect behavior.
 */

int mlt_producer_seek( mlt_producer this, mlt_position position )
{
        // Determine eof handling
        mlt_properties properties = MLT_PRODUCER_PROPERTIES( this );
        char *eof = mlt_properties_get( properties, "eof" );
        int use_points = 1 - mlt_properties_get_int( properties, "ignore_points" );

        // Recursive behaviour for cuts - repositions parent and then repositions cut
        // hence no return on this condition
        if ( mlt_producer_is_cut( this ) )
                mlt_producer_seek( mlt_producer_cut_parent( this ), position + mlt_producer_get_in( this ) );

        // Check bounds
        if ( position < 0 || mlt_producer_get_playtime( this ) == 0 )
        {
                position = 0;
        }
        else if ( use_points && ( eof == NULL || !strcmp( eof, "pause" ) ) && position >= mlt_producer_get_playtime( this ) )
        {
                mlt_producer_set_speed( this, 0 );
                position = mlt_producer_get_playtime( this ) - 1;
        }
        else if ( use_points && !strcmp( eof, "loop" ) && position >= mlt_producer_get_playtime( this ) )
        {
                position = (int)position % (int)mlt_producer_get_playtime( this );
        }

        // Set the position
        mlt_properties_set_position( MLT_PRODUCER_PROPERTIES( this ), "_position", position );

        // Calculate the absolute frame
        mlt_properties_set_position( MLT_PRODUCER_PROPERTIES( this ), "_frame", use_points * mlt_producer_get_in( this ) + position );

        return 0;
}

/** Get the current position (relative to in point).
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return the position of the "play head" relative to its beginning
 */

mlt_position mlt_producer_position( mlt_producer this )
{
        return mlt_properties_get_position( MLT_PRODUCER_PROPERTIES( this ), "_position" );
}

/** Get the current position (relative to start of producer).
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return the position of the "play head" regardless of the in point
 */

mlt_position mlt_producer_frame( mlt_producer this )
{
        return mlt_properties_get_position( MLT_PRODUCER_PROPERTIES( this ), "_frame" );
}

/** Set the playing speed.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \param speed the new speed as a relative factor (1.0 = normal)
 * \return
 */

int mlt_producer_set_speed( mlt_producer this, double speed )
{
        return mlt_properties_set_double( MLT_PRODUCER_PROPERTIES( this ), "_speed", speed );
}

/** Get the playing speed.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return the speed as a relative factor (1.0 = normal)
 */

double mlt_producer_get_speed( mlt_producer this )
{
        return mlt_properties_get_double( MLT_PRODUCER_PROPERTIES( this ), "_speed" );
}

/** Get the frames per second.
 *
 * This is determined by the producer's profile.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return the video refresh rate
 */

double mlt_producer_get_fps( mlt_producer this )
{
        mlt_profile profile = mlt_service_profile( MLT_PRODUCER_SERVICE( this ) );
        return mlt_profile_fps( profile );
}

/** Set the in and out points.
 *
 * The in point is where play out should start relative to the natural start
 * of the underlying file. The out point is where play out should end, also
 * relative to the start of the underlying file. If the underlying resource is
 * a live stream, then the in point is an offset relative to first usable
 * sample.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \param in the relative starting time; a negative value is the same as 0
 * \param out the relative ending time; a negative value is the same as length - 1
 * \return false
 */

int mlt_producer_set_in_and_out( mlt_producer this, mlt_position in, mlt_position out )
{
        mlt_properties properties = MLT_PRODUCER_PROPERTIES( this );

        // Correct ins and outs if necessary
        if ( in < 0 )
                in = 0;
        else if ( in >= mlt_producer_get_length( this ) )
                in = mlt_producer_get_length( this ) - 1;

        if ( ( out < 0 || out >= mlt_producer_get_length( this ) ) && !mlt_producer_is_blank( this ) )
                out = mlt_producer_get_length( this ) - 1;
        else if ( ( out < 0 || out >= mlt_producer_get_length( this ) ) && mlt_producer_is_blank( this ) )
                mlt_properties_set_position( MLT_PRODUCER_PROPERTIES( this ), "length", out + 1 );
        else if ( out < 0 )
                out = 0;

        // Swap ins and outs if wrong
        if ( out < in )
        {
                mlt_position t = in;
                in = out;
                out = t;
        }

        // Set the values
        mlt_events_block( properties, properties );
        mlt_properties_set_position( properties, "in", in );
        mlt_events_unblock( properties, properties );
        mlt_properties_set_position( properties, "out", out );

        return 0;
}

/** Physically reduce the producer (typically a cut) to a 0 length.
 *  Essentially, all 0 length cuts should be immediately removed by containers.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return false
 */

int mlt_producer_clear( mlt_producer this )
{
        if ( this != NULL )
        {
                mlt_properties properties = MLT_PRODUCER_PROPERTIES( this );
                mlt_events_block( properties, properties );
                mlt_properties_set_position( properties, "in", 0 );
                mlt_events_unblock( properties, properties );
                mlt_properties_set_position( properties, "out", -1 );
        }
        return 0;
}

/** Get the in point.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return the in point
 */

mlt_position mlt_producer_get_in( mlt_producer this )
{
        return mlt_properties_get_position( MLT_PRODUCER_PROPERTIES( this ), "in" );
}

/** Get the out point.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return the out point
 */

mlt_position mlt_producer_get_out( mlt_producer this )
{
        return mlt_properties_get_position( MLT_PRODUCER_PROPERTIES( this ), "out" );
}

/** Get the total play time.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return the playable (based on in and out points) duration
 */

mlt_position mlt_producer_get_playtime( mlt_producer this )
{
        return mlt_producer_get_out( this ) - mlt_producer_get_in( this ) + 1;
}

/** Get the total, unedited length of the producer.
 *
 * The value returned by a live streaming producer is unknown.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return the duration of the producer regardless of in and out points
 */

mlt_position mlt_producer_get_length( mlt_producer this )
{
        return mlt_properties_get_position( MLT_PRODUCER_PROPERTIES( this ), "length" );
}

/** Prepare for next frame.
 *
 * Advance the play out position. If the speed is less than zero, it will
 * move the play out position in the reverse direction.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 */

void mlt_producer_prepare_next( mlt_producer this )
{
        if ( mlt_producer_get_speed( this ) != 0 )
                mlt_producer_seek( this, mlt_producer_position( this ) + mlt_producer_get_speed( this ) );
}

/** Get a frame.
 *
 * This is the implementation of the \p get_frame virtual function.
 * It requests a new frame object from the actual producer for the current
 * play out position. The producer and its filters can add information and
 * operations to the frame object in their get_frame handlers.
 *
 * \private \memberof mlt_producer_s
 * \param service a service
 * \param[out] frame a frame by reference
 * \param index as determined by the actual producer
 * \return true if there was an error
 * \todo Learn more about the details and document how certain properties affect
 * its behavior.
 */

static int producer_get_frame( mlt_service service, mlt_frame_ptr frame, int index )
{
        int result = 1;
        mlt_producer this = service != NULL ? service->child : NULL;

        if ( this != NULL && !mlt_producer_is_cut( this ) )
        {
                // Get the properties of this producer
                mlt_properties properties = MLT_PRODUCER_PROPERTIES( this );

                // Determine eof handling
                char *eof = mlt_properties_get( MLT_PRODUCER_PROPERTIES( this ), "eof" );

                // Get the speed of the producer
                double speed = mlt_producer_get_speed( this );

                // We need to use the clone if it's specified
                mlt_producer clone = mlt_properties_get_data( properties, "use_clone", NULL );

                // If no clone is specified, use this
                clone = clone == NULL ? this : clone;

                // A properly instatiated producer will have a get_frame method...
                if ( this->get_frame == NULL || ( !strcmp( eof, "continue" ) && mlt_producer_position( this ) > mlt_producer_get_out( this ) ) )
                {
                        // Generate a test frame
                        *frame = mlt_frame_init( service );

                        // Set the position
                        result = mlt_frame_set_position( *frame, mlt_producer_position( this ) );

                        // Mark as a test card
                        mlt_properties_set_int( MLT_FRAME_PROPERTIES( *frame ), "test_image", 1 );
                        mlt_properties_set_int( MLT_FRAME_PROPERTIES( *frame ), "test_audio", 1 );

                        // Calculate the next position
                        mlt_producer_prepare_next( this );
                }
                else
                {
                        // Get the frame from the implementation
                        result = this->get_frame( clone, frame, index );
                }

                // Copy the fps and speed of the producer onto the frame
                properties = MLT_FRAME_PROPERTIES( *frame );
                mlt_properties_set_double( properties, "_speed", speed );
                mlt_properties_set_int( properties, "test_audio", mlt_frame_is_test_audio( *frame ) );
                mlt_properties_set_int( properties, "test_image", mlt_frame_is_test_card( *frame ) );
                if ( mlt_properties_get_data( properties, "_producer", NULL ) == NULL )
                        mlt_properties_set_data( properties, "_producer", service, 0, NULL, NULL );
        }
        else if ( this != NULL )
        {
                // Get the speed of the cut
                double speed = mlt_producer_get_speed( this );

                // Get the parent of this cut
                mlt_producer parent = mlt_producer_cut_parent( this );

                // Get the properties of the parent
                mlt_properties parent_properties = MLT_PRODUCER_PROPERTIES( parent );

                // Get the properties of the cut
                mlt_properties properties = MLT_PRODUCER_PROPERTIES( this );

                // Determine the clone index
                int clone_index = mlt_properties_get_int( properties, "_clone" );

                // Determine the clone to use
                mlt_producer clone = this;

                if ( clone_index > 0 )
                {
                        char key[ 25 ];
                        sprintf( key, "_clone.%d", clone_index - 1 );
                        clone = mlt_properties_get_data( MLT_PRODUCER_PROPERTIES( mlt_producer_cut_parent( this ) ), key, NULL );
                        if ( clone == NULL ) mlt_log( service, MLT_LOG_ERROR, "requested clone doesn't exist %d\n", clone_index );
                        clone = clone == NULL ? this : clone;
                }
                else
                {
                        clone = parent;
                }

                // We need to seek to the correct position in the clone
                mlt_producer_seek( clone, mlt_producer_get_in( this ) + mlt_properties_get_int( properties, "_position" ) );

                // Assign the clone property to the parent
                mlt_properties_set_data( parent_properties, "use_clone", clone, 0, NULL, NULL );

                // Now get the frame from the parents service
                result = mlt_service_get_frame( MLT_PRODUCER_SERVICE( parent ), frame, index );

                // We're done with the clone now
                mlt_properties_set_data( parent_properties, "use_clone", NULL, 0, NULL, NULL );

                // This is useful and required by always_active transitions to determine in/out points of the cut
                if ( mlt_properties_get_data( MLT_FRAME_PROPERTIES( *frame ), "_producer", NULL ) == MLT_PRODUCER_SERVICE( parent ) )
                        mlt_properties_set_data( MLT_FRAME_PROPERTIES( *frame ), "_producer", this, 0, NULL, NULL );

                mlt_properties_set_double( MLT_FRAME_PROPERTIES( *frame ), "_speed", speed );
                mlt_producer_prepare_next( this );
        }
        else
        {
                *frame = mlt_frame_init( service );
                result = 0;
        }

        // Pass on all meta properties from the producer/cut on to the frame
        if ( *frame != NULL && this != NULL )
        {
                int i = 0;
                mlt_properties p_props = MLT_PRODUCER_PROPERTIES( this );
                mlt_properties f_props = MLT_FRAME_PROPERTIES( *frame );
                int count = mlt_properties_count( p_props );
                for ( i = 0; i < count; i ++ )
                {
                        char *name = mlt_properties_get_name( p_props, i );
                        if ( !strncmp( name, "meta.", 5 ) )
                                mlt_properties_set( f_props, name, mlt_properties_get( p_props, name ) );
                        else if ( !strncmp( name, "set.", 4 ) )
                                mlt_properties_set( f_props, name + 4, mlt_properties_get( p_props, name ) );
                }
        }

        return result;
}

/** Attach a filter.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \param filter the filter to attach
 * \return true if there was an error
 */

int mlt_producer_attach( mlt_producer this, mlt_filter filter )
{
        return mlt_service_attach( MLT_PRODUCER_SERVICE( this ), filter );
}

/** Detach a filter.
 *
 * \public \memberof mlt_producer_s
 * \param this a service
 * \param filter the filter to detach
 * \return true if there was an error
 */

int mlt_producer_detach( mlt_producer this, mlt_filter filter )
{
        return mlt_service_detach( MLT_PRODUCER_SERVICE( this ), filter );
}

/** Retrieve a filter.
 *
 * \public \memberof mlt_producer_s
 * \param this a service
 * \param index which filter to retrieve
 * \return the filter or null if there was an error
 */

mlt_filter mlt_producer_filter( mlt_producer this, int index )
{
        return mlt_service_filter( MLT_PRODUCER_SERVICE( this ), index );
}

/** Clone this producer.
 *
 * \private \memberof mlt_producer_s
 * \param this a producer
 * \return a new producer that is a copy of \p this
 * \see mlt_producer_set_clones
 */

static mlt_producer mlt_producer_clone( mlt_producer this )
{
        mlt_producer clone = NULL;
        mlt_properties properties = MLT_PRODUCER_PROPERTIES( this );
        char *resource = mlt_properties_get( properties, "resource" );
        char *service = mlt_properties_get( properties, "mlt_service" );
        mlt_profile profile = mlt_service_profile( MLT_PRODUCER_SERVICE( this ) );

        mlt_events_block( mlt_factory_event_object( ), mlt_factory_event_object( ) );

        if ( service != NULL )
                clone = mlt_factory_producer( profile, service, resource );

        if ( clone == NULL && resource != NULL )
                clone = mlt_factory_producer( profile, NULL, resource );

        if ( clone != NULL )
                mlt_properties_inherit( MLT_PRODUCER_PROPERTIES( clone ), properties );

        mlt_events_unblock( mlt_factory_event_object( ), mlt_factory_event_object( ) );

        return clone;
}

/** Create clones.
 *
 * \private \memberof mlt_producer_s
 * \param this a producer
 * \param clones the number of copies to make
 * \see mlt_producer_optimise
 */

static void mlt_producer_set_clones( mlt_producer this, int clones )
{
        mlt_producer parent = mlt_producer_cut_parent( this );
        mlt_properties properties = MLT_PRODUCER_PROPERTIES( parent );
        int existing = mlt_properties_get_int( properties, "_clones" );
        int i = 0;
        char key[ 25 ];

        // If the number of existing clones is different, then create/remove as necessary
        if ( existing != clones )
        {
                if ( existing < clones )
                {
                        for ( i = existing; i < clones; i ++ )
                        {
                                mlt_producer clone = mlt_producer_clone( parent );
                                sprintf( key, "_clone.%d", i );
                                mlt_properties_set_data( properties, key, clone, 0, ( mlt_destructor )mlt_producer_close, NULL );
                        }
                }
                else
                {
                        for ( i = clones; i < existing; i ++ )
                        {
                                sprintf( key, "_clone.%d", i );
                                mlt_properties_set_data( properties, key, NULL, 0, NULL, NULL );
                        }
                }
        }

        // Ensure all properties on the parent are passed to the clones
        for ( i = 0; i < clones; i ++ )
        {
                mlt_producer clone = NULL;
                sprintf( key, "_clone.%d", i );
                clone = mlt_properties_get_data( properties, key, NULL );
                if ( clone != NULL )
                        mlt_properties_pass( MLT_PRODUCER_PROPERTIES( clone ), properties, "" );
        }

        // Update the number of clones on the properties
        mlt_properties_set_int( properties, "_clones", clones );
}

/** \brief private to mlt_producer_s, used by mlt_producer_optimise() */

typedef struct
{
        int multitrack;
        int track;
        int position;
        int length;
        int offset;
}
track_info;

/** \brief private to mlt_producer_s, used by mlt_producer_optimise() */

typedef struct
{
        mlt_producer cut;
        int start;
        int end;
}
clip_references;

static int intersect( clip_references *a, clip_references *b )
{
        int diff = ( a->start - b->start ) + ( a->end - b->end );
        return diff >= 0 && diff < ( a->end - a->start + 1 );
}

static int push( mlt_parser this, int multitrack, int track, int position )
{
        mlt_properties properties = mlt_parser_properties( this );
        mlt_deque stack = mlt_properties_get_data( properties, "stack", NULL );
        track_info *info = malloc( sizeof( track_info ) );
        info->multitrack = multitrack;
        info->track = track;
        info->position = position;
        info->length = 0;
        info->offset = 0;
        return mlt_deque_push_back( stack, info );
}

static track_info *pop( mlt_parser this )
{
        mlt_properties properties = mlt_parser_properties( this );
        mlt_deque stack = mlt_properties_get_data( properties, "stack", NULL );
        return mlt_deque_pop_back( stack );
}

static track_info *peek( mlt_parser this )
{
        mlt_properties properties = mlt_parser_properties( this );
        mlt_deque stack = mlt_properties_get_data( properties, "stack", NULL );
        return mlt_deque_peek_back( stack );
}

static int on_start_multitrack( mlt_parser this, mlt_multitrack object )
{
        track_info *info = peek( this );
        return push( this, info->multitrack ++, info->track, info->position );
}

static int on_start_track( mlt_parser this )
{
        track_info *info = peek( this );
        info->position -= info->offset;
        info->length -= info->offset;
        return push( this, info->multitrack, info->track ++, info->position );
}

static int on_start_producer( mlt_parser this, mlt_producer object )
{
        mlt_properties properties = mlt_parser_properties( this );
        mlt_properties producers = mlt_properties_get_data( properties, "producers", NULL );
        mlt_producer parent = mlt_producer_cut_parent( object );
        if ( mlt_service_identify( ( mlt_service )mlt_producer_cut_parent( object ) ) == producer_type && mlt_producer_is_cut( object ) )
        {
                int ref_count = 0;
                clip_references *old_refs = NULL;
                clip_references *refs = NULL;
                char key[ 50 ];
                int count = 0;
                track_info *info = peek( this );
                sprintf( key, "%p", parent );
                mlt_properties_get_data( producers, key, &count );
                mlt_properties_set_data( producers, key, parent, ++ count, NULL, NULL );
                old_refs = mlt_properties_get_data( properties, key, &ref_count );
                refs = malloc( ( ref_count + 1 ) * sizeof( clip_references ) );
                if ( old_refs != NULL )
                        memcpy( refs, old_refs, ref_count * sizeof( clip_references ) );
                mlt_properties_set_int( MLT_PRODUCER_PROPERTIES( object ), "_clone", -1 );
                refs[ ref_count ].cut = object;
                refs[ ref_count ].start = info->position;
                refs[ ref_count ].end = info->position + mlt_producer_get_playtime( object ) - 1;
                mlt_properties_set_data( properties, key, refs, ++ ref_count, free, NULL );
                info->position += mlt_producer_get_playtime( object );
                info->length += mlt_producer_get_playtime( object );
        }
        return 0;
}

static int on_end_track( mlt_parser this )
{
        track_info *track = pop( this );
        track_info *multi = peek( this );
        multi->length += track->length;
        multi->position += track->length;
        multi->offset = track->length;
        free( track );
        return 0;
}

static int on_end_multitrack( mlt_parser this, mlt_multitrack object )
{
        track_info *multi = pop( this );
        track_info *track = peek( this );
        track->position += multi->length;
        track->length += multi->length;
        free( multi );
        return 0;
}

/** Optimise for overlapping cuts from the same clip.
 *
 * \todo learn more about this
 * \public \memberof mlt_producer_s
 * \param this a producer
 * \return true if there was an error
 */

int mlt_producer_optimise( mlt_producer this )
{
        int error = 1;
        mlt_parser parser = mlt_parser_new( );
        if ( parser != NULL )
        {
                int i = 0, j = 0, k = 0;
                mlt_properties properties = mlt_parser_properties( parser );
                mlt_properties producers = mlt_properties_new( );
                mlt_deque stack = mlt_deque_init( );
                mlt_properties_set_data( properties, "producers", producers, 0, ( mlt_destructor )mlt_properties_close, NULL );
                mlt_properties_set_data( properties, "stack", stack, 0, ( mlt_destructor )mlt_deque_close, NULL );
                parser->on_start_producer = on_start_producer;
                parser->on_start_track = on_start_track;
                parser->on_end_track = on_end_track;
                parser->on_start_multitrack = on_start_multitrack;
                parser->on_end_multitrack = on_end_multitrack;
                push( parser, 0, 0, 0 );
                mlt_parser_start( parser, MLT_PRODUCER_SERVICE( this ) );
                free( pop( parser ) );
                for ( k = 0; k < mlt_properties_count( producers ); k ++ )
                {
                        char *name = mlt_properties_get_name( producers, k );
                        int count = 0;
                        int clones = 0;
                        int max_clones = 0;
                        mlt_producer producer = mlt_properties_get_data( producers, name, &count );
                        if ( producer != NULL && count > 1 )
                        {
                                clip_references *refs = mlt_properties_get_data( properties, name, &count );
                                for ( i = 0; i < count; i ++ )
                                {
                                        clones = 0;
                                        for ( j = i + 1; j < count; j ++ )
                                        {
                                                if ( intersect( &refs[ i ], &refs[ j ] ) )
                                                {
                                                        clones ++;
                                                        mlt_properties_set_int( MLT_PRODUCER_PROPERTIES( refs[ j ].cut ), "_clone", clones );
                                                }
                                        }
                                        if ( clones > max_clones )
                                                max_clones = clones;
                                }

                                for ( i = 0; i < count; i ++ )
                                {
                                        mlt_producer cut = refs[ i ].cut;
                                        if ( mlt_properties_get_int( MLT_PRODUCER_PROPERTIES( cut ), "_clone" ) == -1 )
                                                mlt_properties_set_int( MLT_PRODUCER_PROPERTIES( cut ), "_clone", 0 );
                                }

                                mlt_producer_set_clones( producer, max_clones );
                        }
                        else if ( producer != NULL )
                        {
                                clip_references *refs = mlt_properties_get_data( properties, name, &count );
                                for ( i = 0; i < count; i ++ )
                                {
                                        mlt_producer cut = refs[ i ].cut;
                                        mlt_properties_set_int( MLT_PRODUCER_PROPERTIES( cut ), "_clone", 0 );
                                }
                                mlt_producer_set_clones( producer, 0 );
                        }
                }
                mlt_parser_close( parser );
        }
        return error;
}

/** Close the producer.
 *
 * Destroys the producer and deallocates its resources managed by its
 * properties list. This will call the close virtual function. Therefore, a
 * subclass that defines its own close function should set its virtual close
 * function to NULL prior to calling this to avoid circular calls.
 *
 * \public \memberof mlt_producer_s
 * \param this a producer
 */

void mlt_producer_close( mlt_producer this )
{
        if ( this != NULL && mlt_properties_dec_ref( MLT_PRODUCER_PROPERTIES( this ) ) <= 0 )
        {
                this->parent.close = NULL;

                if ( this->close != NULL )
                {
                        this->close( this->close_object );
                }
                else
                {
                        int destroy = mlt_producer_is_cut( this );

#if _MLT_PRODUCER_CHECKS_ == 1
                        // Show debug info
                        mlt_properties_debug( MLT_PRODUCER_PROPERTIES( this ), "Producer closing", stderr );
#endif

#ifdef _MLT_PRODUCER_CHECKS_
                        // Show current stats - these should match when the app is closed
                        mlt_log( MLT_PRODUCER_SERVICE( this ), MLT_LOG_DEBUG, "Producers created %d, destroyed %d\n", producers_created, ++producers_destroyed );
#endif

                        mlt_service_close( &this->parent );

                        if ( destroy )
                                free( this );
                }
        }
}