research.m1stereo.tv/gitweb/ - melted/blob - src/framework/mlt_multitrack.c

   1 /*
   2  * mlt_multitrack.c -- multitrack service class
   3  * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
   4  * Author: Charles Yates <charles.yates@pandora.be>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19  */
  20
  21 #include "config.h"
  22
  23 #include "mlt_multitrack.h"
  24 #include "mlt_frame.h"
  25
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28
  29 /** Private definition.
  30 */
  31
  32 struct mlt_multitrack_s
  33 {
  34         // We're extending producer here
  35         struct mlt_producer_s parent;
  36         mlt_producer *list;
  37         int size;
  38         int count;
  39 };
  40
  41 /** Forward reference.
  42 */
  43
  44 static int producer_get_frame( mlt_producer parent, mlt_frame_ptr frame, int index );
  45
  46 /** Constructor.
  47 */
  48
  49 mlt_multitrack mlt_multitrack_init( )
  50 {
  51         // Allocate the multitrack object
  52         mlt_multitrack this = calloc( sizeof( struct mlt_multitrack_s ), 1 );
  53
  54         if ( this != NULL )
  55         {
  56                 mlt_producer producer = &this->parent;
  57                 if ( mlt_producer_init( producer, this ) == 0 )
  58                 {
  59                         producer->get_frame = producer_get_frame;
  60                 }
  61                 else
  62                 {
  63                         free( this );
  64                         this = NULL;
  65                 }
  66         }
  67
  68         return this;
  69 }
  70
  71 /** Get the producer associated to this multitrack.
  72 */
  73
  74 mlt_producer mlt_multitrack_producer( mlt_multitrack this )
  75 {
  76         return &this->parent;
  77 }
  78
  79 /** Get the service associated this multitrack.
  80 */
  81
  82 mlt_service mlt_multitrack_service( mlt_multitrack this )
  83 {
  84         return mlt_producer_service( mlt_multitrack_producer( this ) );
  85 }
  86
  87 /** Get the properties associated this multitrack.
  88 */
  89
  90 mlt_properties mlt_multitrack_properties( mlt_multitrack this )
  91 {
  92         return mlt_service_properties( mlt_multitrack_service( this ) );
  93 }
  94
  95 /** Initialise timecode related information.
  96 */
  97
  98 void mlt_multitrack_refresh( mlt_multitrack this )
  99 {
 100         int i = 0;
 101
 102         // Obtain the properties of this multitrack
 103         mlt_properties properties = mlt_multitrack_properties( this );
 104
 105         // We need to ensure that the multitrack reports the longest track as its length
 106         mlt_timecode length = 0;
 107
 108         // We need to ensure that fps are the same on all services
 109         double fps = 0;
 110
 111         // Obtain stats on all connected services
 112         for ( i = 0; i < this->count; i ++ )
 113         {
 114                 // Get the producer from this index
 115                 mlt_producer producer = this->list[ i ];
 116
 117                 // If it's allocated then, update our stats
 118                 if ( producer != NULL )
 119                 {
 120                         // Determine the longest length
 121                         length = mlt_producer_get_length( producer ) > length ? mlt_producer_get_length( producer ) : length;
 122
 123                         // Handle fps
 124                         if ( fps == 0 )
 125                         {
 126                                 // This is the first producer, so it controls the fps
 127                                 fps = mlt_producer_get_fps( producer );
 128                         }
 129                         else if ( fps != mlt_producer_get_fps( producer ) )
 130                         {
 131                                 // Generate a warning for now - the following attempt to fix may fail
 132                                 fprintf( stderr, "Warning: fps mismatch on track %d\n", i );
 133
 134                                 // It should be safe to impose fps on an image producer, but not necessarily safe for video
 135                                 mlt_properties_set_double( mlt_producer_properties( producer ), "fps", fps );
 136                         }
 137                 }
 138         }
 139
 140         // Update multitrack properties now - we'll not destroy the in point here
 141         mlt_properties_set_timecode( properties, "length", length );
 142         mlt_properties_set_timecode( properties, "out", length );
 143         mlt_properties_set_timecode( properties, "playtime", length - mlt_properties_get_timecode( properties, "in" ) );
 144 }
 145
 146 /** Connect a producer to a given track.
 147 */
 148
 149 int mlt_multitrack_connect( mlt_multitrack this, mlt_producer producer, int track )
 150 {
 151         // Connect to the producer to ourselves at the specified track
 152         int result = mlt_service_connect_producer( mlt_multitrack_service( this ), mlt_producer_service( producer ), track );
 153
 154         if ( result == 0 )
 155         {
 156                 // Resize the producer list if need be
 157                 if ( track >= this->size )
 158                 {
 159                         int i;
 160                         this->list = realloc( this->list, ( track + 10 ) * sizeof( mlt_producer ) );
 161                         for ( i = this->size; i < track + 10; i ++ )
 162                                 this->list[ i ] = NULL;
 163                         this->size = track + 10;
 164                 }
 165
 166                 // Assign the track in our list here
 167                 this->list[ track ] = producer;
 168
 169                 // Increment the track count if need be
 170                 if ( track >= this->count )
 171                         this->count = track + 1;
 172
 173                 // Refresh our stats
 174                 mlt_multitrack_refresh( this );
 175         }
 176
 177         return result;
 178 }
 179
 180 /** Get frame method.
 181
 182         Special case here: The multitrack must be used in a conjunction with a downstream
 183         tractor-type service, ie:
 184
 185         Producer1 \
 186         Producer2 - multitrack - { filters/transitions } - tractor - consumer
 187         Producer3 /
 188
 189         The get_frame of a tractor pulls frames from it's connected service on all tracks and
 190         will terminate as soon as it receives a test card with a last_track property. The
 191         important case here is that the mulitrack does not move to the next frame until all
 192         tracks have been pulled.
 193
 194         Reasoning: In order to seek on a network such as above, the multitrack needs to ensure
 195         that all producers are positioned on the same frame. It uses the 'last track' logic
 196         to determine when to move to the next frame.
 197
 198         Flaw: if a transition is configured to read from a b-track which happens to trigger
 199         the last frame logic (ie: it's configured incorrectly), then things are going to go
 200         out of sync.
 201
 202         See playlist logic too.
 203 */
 204
 205 static int producer_get_frame( mlt_producer parent, mlt_frame_ptr frame, int index )
 206 {
 207         // Get the mutiltrack object
 208         mlt_multitrack this = parent->child;
 209
 210         // Check if we have a track for this index
 211         if ( index < this->count && this->list[ index ] != NULL )
 212         {
 213                 // Get the producer for this track
 214                 mlt_producer producer = this->list[ index ];
 215
 216                 // Obtain the current timecode
 217                 uint64_t position = mlt_producer_frame( parent );
 218
 219                 // Make sure we're at the same point
 220                 mlt_producer_seek_frame( producer, position );
 221
 222                 // Get the frame from the producer
 223                 mlt_service_get_frame( mlt_producer_service( producer ), frame, 0 );
 224         }
 225         else
 226         {
 227                 // Generate a test frame
 228                 *frame = mlt_frame_init( );
 229
 230                 // Let tractor know if we've reached the end
 231                 mlt_properties_set_int( mlt_frame_properties( *frame ), "last_track", index >= this->count );
 232
 233                 // Update timecode on the frame we're creating
 234                 mlt_frame_set_timecode( *frame, mlt_producer_position( parent ) );
 235
 236                 // Move on to the next frame
 237                 if ( index >= this->count )
 238                         mlt_producer_prepare_next( parent );
 239
 240                 // Refresh our stats
 241                 mlt_multitrack_refresh( this );
 242         }
 243
 244         return 0;
 245 }
 246
 247 /** Close this instance.
 248 */
 249
 250 void mlt_multitrack_close( mlt_multitrack this )
 251 {
 252         // Close the producer
 253         mlt_producer_close( &this->parent );
 254
 255         // Free the list
 256         free( this->list );
 257
 258         // Free the object
 259         free( this );
 260 }