fix segfault on failure to decode with multi-threaded decoding

self->got_picture was somewhat redundant with self->av_frame, but not
synchronized and not ever really reset. So, just remove that state and
use the state of self->av_frame and local got_picture.

diff --git a/src/modules/avformat/producer_avformat.c b/src/modules/avformat/producer_avformat.c
index 273454019aed26170378f0001c484d3499417667..39fbda091b5a5c4a47ab8bff6815a75987f29def 100644 (file)
--- a/src/modules/avformat/producer_avformat.c
+++ b/src/modules/avformat/producer_avformat.c
@@ -101,7 +101,6 @@ struct producer_avformat_s
        int seekable;
        int64_t current_position;
        mlt_position nonseek_position;
-       int got_picture;
        int top_field_first;
        uint8_t *audio_buffer[ MAX_AUDIO_STREAMS ];
        size_t audio_buffer_size[ MAX_AUDIO_STREAMS ];
@@ -1415,6 +1414,8 @@ static int producer_get_image( mlt_frame frame, uint8_t **buffer, mlt_image_form
        AVCodecContext *codec_context = stream->codec;
 
        uint8_t *alpha = NULL;
+       int got_picture = 0;
+       int image_size = 0;
 
        // Get the image cache
        if ( ! self->image_cache && ! mlt_properties_get_int( properties, "noimagecache" ) )
@@ -1451,7 +1452,7 @@ static int producer_get_image( mlt_frame frame, uint8_t **buffer, mlt_image_form
                                mlt_properties_set_data( frame_properties, "avformat.image_cache", item, 0, ( mlt_destructor )mlt_cache_item_close, NULL );
                                mlt_frame_set_image( frame, *buffer, size, NULL );
                        }
-                       self->got_picture = 1;
+                       got_picture = 1;
 
                        // check for alpha
                        item = mlt_cache_get( self->alpha_cache, (void*) position );
@@ -1467,7 +1468,6 @@ static int producer_get_image( mlt_frame frame, uint8_t **buffer, mlt_image_form
                }
        }
        // Cache miss
-       int image_size = 0;
 
        // Packet
        AVPacket pkt;
@@ -1513,7 +1513,7 @@ static int producer_get_image( mlt_frame frame, uint8_t **buffer, mlt_image_form
                *format = pick_format( codec_context->pix_fmt );
 
        // Duplicate the last image if necessary
-       if ( self->av_frame && self->av_frame->linesize[0] && self->got_picture
+       if ( self->av_frame && self->av_frame->linesize[0]
                 && ( paused
                          || self->current_position == req_position
                          || ( !use_new_seek && self->current_position > req_position ) ) )
@@ -1541,16 +1541,14 @@ static int producer_get_image( mlt_frame frame, uint8_t **buffer, mlt_image_form
 #endif
                        convert_image( self->av_frame, *buffer, codec_context->pix_fmt,
                                format, *width, *height, self->colorspace, &alpha );
+                       got_picture = 1;
                }
-               else
-                       mlt_frame_get_image( frame, buffer, format, width, height, writable );
        }
        else
        {
                int ret = 0;
                int64_t int_position = 0;
                int decode_errors = 0;
-               int got_picture = 0;
 
                av_init_packet( &pkt );
 
@@ -1750,7 +1748,6 @@ static int producer_get_image( mlt_frame frame, uint8_t **buffer, mlt_image_form
                                                format, *width, *height, self->colorspace, &alpha );
                                        self->top_field_first |= self->av_frame->top_field_first;
                                        self->current_position = int_position;
-                                       self->got_picture = 1;
                                }
                                else
                                {
@@ -1762,7 +1759,7 @@ static int producer_get_image( mlt_frame frame, uint8_t **buffer, mlt_image_form
                }
        }
 
-       if ( self->got_picture && image_size > 0 && self->image_cache )
+       if ( image_size > 0 && self->image_cache )
        {
                // Copy buffer to image cache   
                uint8_t *image = mlt_pool_alloc( image_size );
@@ -1776,8 +1773,11 @@ static int producer_get_image( mlt_frame frame, uint8_t **buffer, mlt_image_form
                        mlt_cache_put( self->alpha_cache, (void*) position, image, alpha_size, mlt_pool_release );
                }
        }
+
        // Try to duplicate last image if there was a decoding failure
-       else if ( !image_size && self->av_frame && self->av_frame->linesize[0] )
+       // TODO: with multithread decoding a partial frame decoding resulting
+       // in failure also resets av_frame making test below fail.
+       if ( !image_size && self->av_frame && self->av_frame->linesize[0] )
        {
                // Duplicate it
                if ( ( image_size = allocate_buffer( frame, codec_context, buffer, format, width, height ) ) )
@@ -1802,10 +1802,8 @@ static int producer_get_image( mlt_frame frame, uint8_t **buffer, mlt_image_form
 #endif
                        convert_image( self->av_frame, *buffer, codec_context->pix_fmt,
                                format, *width, *height, self->colorspace, &alpha );
-                       self->got_picture = 1;
+                       got_picture = 1;
                }
-               else
-                       mlt_frame_get_image( frame, buffer, format, width, height, writable );
        }
 
        // Regardless of speed, we expect to get the next frame (cos we ain't too bright)
@@ -1837,7 +1835,7 @@ exit_get_image:
        if ( alpha )
                mlt_frame_set_alpha( frame, alpha, (*width) * (*height), mlt_pool_release );
 
-       return !self->got_picture;
+       return !got_picture;
 }
 
 /** Process properties as AVOptions and apply to AV context obj