2 * mlt_multitrack.c -- multitrack service class
3 * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
4 * Author: Charles Yates <charles.yates@pandora.be>
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.
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.
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.
23 #include "mlt_multitrack.h"
24 #include "mlt_frame.h"
29 /** Private definition.
32 struct mlt_multitrack_s
34 // We're extending producer here
35 struct mlt_producer_s parent
;
41 /** Forward reference.
44 static int producer_get_frame( mlt_producer parent
, mlt_frame_ptr frame
, int index
);
49 mlt_multitrack
mlt_multitrack_init( )
51 // Allocate the multitrack object
52 mlt_multitrack
this = calloc( sizeof( struct mlt_multitrack_s
), 1 );
56 mlt_producer producer
= &this->parent
;
57 if ( mlt_producer_init( producer
, this ) == 0 )
59 producer
->get_frame
= producer_get_frame
;
71 /** Get the producer associated to this multitrack.
74 mlt_producer
mlt_multitrack_producer( mlt_multitrack
this )
79 /** Get the service associated this multitrack.
82 mlt_service
mlt_multitrack_service( mlt_multitrack
this )
84 return mlt_producer_service( mlt_multitrack_producer( this ) );
87 /** Get the properties associated this multitrack.
90 mlt_properties
mlt_multitrack_properties( mlt_multitrack
this )
92 return mlt_service_properties( mlt_multitrack_service( this ) );
95 /** Initialise timecode related information.
98 static void mlt_multitrack_refresh( mlt_multitrack
this )
102 // Obtain the properties of this multitrack
103 mlt_properties properties
= mlt_multitrack_properties( this );
105 // We need to ensure that the multitrack reports the longest track as its length
106 mlt_timecode length
= 0;
108 // We need to ensure that fps are the same on all services
111 // Obtain stats on all connected services
112 for ( i
= 0; i
< this->count
; i
++ )
114 // Get the producer from this index
115 mlt_producer producer
= this->list
[ i
];
117 // If it's allocated then, update our stats
118 if ( producer
!= NULL
)
120 // Determine the longest length
121 length
= mlt_producer_get_length( producer
) > length ?
mlt_producer_get_length( producer
) : length
;
126 // This is the first producer, so it controls the fps
127 fps
= mlt_producer_get_fps( producer
);
129 else if ( fps
!= mlt_producer_get_fps( producer
) )
131 // Generate a warning for now - the following attempt to fix may fail
132 fprintf( stderr
, "Warning: fps mismatch on track %d\n", i
);
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
);
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" ) );
146 /** Connect a producer to a given track.
149 int mlt_multitrack_connect( mlt_multitrack
this, mlt_producer producer
, int track
)
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
);
156 // Resize the producer list if need be
157 if ( track
>= this->size
)
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;
166 // Assign the track in our list here
167 this->list
[ track
] = producer
;
169 // Increment the track count if need be
170 if ( track
>= this->count
)
171 this->count
= track
+ 1;
174 mlt_multitrack_refresh( this );
180 /** Get frame method.
182 Special case here: The multitrack must be used in a conjunction with a downstream
183 tractor-type service, ie:
186 Producer2 - multitrack - { filters/transitions } - tractor - consumer
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.
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.
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
202 See playlist logic too.
205 static int producer_get_frame( mlt_producer parent
, mlt_frame_ptr frame
, int index
)
207 // Get the mutiltrack object
208 mlt_multitrack
this = parent
->child
;
210 // Check if we have a track for this index
211 if ( index
< this->count
&& this->list
[ index
] != NULL
)
213 // Get the producer for this track
214 mlt_producer producer
= this->list
[ index
];
216 // Obtain the current timecode
217 uint64_t position
= mlt_producer_frame( parent
);
219 // Make sure we're at the same point
220 mlt_producer_seek_frame( producer
, position
);
222 // Get the frame from the producer
223 mlt_service_get_frame( mlt_producer_service( producer
), frame
, 0 );
227 // Generate a test frame
228 *frame
= mlt_frame_init( );
230 // Let tractor know if we've reached the end
231 mlt_properties_set_int( mlt_frame_properties( *frame
), "last_track", index
>= this->count
);
233 // Update timecode on the frame we're creating
234 mlt_frame_set_timecode( *frame
, mlt_producer_position( parent
) );
236 // Move on to the next frame
237 if ( index
>= this->count
)
238 mlt_producer_prepare_next( parent
);
244 /** Close this instance.
247 void mlt_multitrack_close( mlt_multitrack
this )
249 // Close the producer
250 mlt_producer_close( &this->parent
);