2 * \file mlt_transition.c
3 * \brief abstraction for all transition services
5 * Copyright (C) 2003-2008 Ushodaya Enterprises Limited
6 * \author Charles Yates <charles.yates@pandora.be>
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 #include "mlt_transition.h"
24 #include "mlt_frame.h"
30 /* Forward references */
32 static int transition_get_frame( mlt_service
this, mlt_frame_ptr frame
, int index
);
34 /** Initialize a new transition.
36 * \public \memberof mlt_transition_s
37 * \param this a transition
38 * \param child the object of a subclass
39 * \return true on error
42 int mlt_transition_init( mlt_transition
this, void *child
)
44 mlt_service service
= &this->parent
;
45 memset( this, 0, sizeof( struct mlt_transition_s
) );
47 if ( mlt_service_init( service
, this ) == 0 )
49 mlt_properties properties
= MLT_TRANSITION_PROPERTIES( this );
51 service
->get_frame
= transition_get_frame
;
52 service
->close
= ( mlt_destructor
)mlt_transition_close
;
53 service
->close_object
= this;
55 mlt_properties_set_position( properties
, "in", 0 );
56 mlt_properties_set_position( properties
, "out", 0 );
57 mlt_properties_set_int( properties
, "a_track", 0 );
58 mlt_properties_set_int( properties
, "b_track", 1 );
65 /** Create and initialize a new transition.
67 * \public \memberof mlt_transition_s
68 * \return a new transition
71 mlt_transition
mlt_transition_new( )
73 mlt_transition
this = calloc( 1, sizeof( struct mlt_transition_s
) );
75 mlt_transition_init( this, NULL
);
79 /** Get the service class interface.
81 * \public \memberof mlt_transition_s
82 * \param this a transition
83 * \return the service class
84 * \see MLT_TRANSITION_SERVICE
87 mlt_service
mlt_transition_service( mlt_transition
this )
89 return this != NULL ?
&this->parent
: NULL
;
92 /** Get the properties interface.
94 * \public \memberof mlt_transition_s
95 * \param this a transition
96 * \return the transition's properties
97 * \see MLT_TRANSITION_PROPERTIES
100 mlt_properties
mlt_transition_properties( mlt_transition
this )
102 return MLT_TRANSITION_PROPERTIES( this );
105 /** Connect this transition with a producers a and b tracks.
107 * \public \memberof mlt_transition_s
108 * \param this a transition
109 * \param producer a producer
110 * \param a_track the track index of the first input
111 * \param b_track the track index of the second index
112 * \return true on error
115 int mlt_transition_connect( mlt_transition
this, mlt_service producer
, int a_track
, int b_track
)
117 int ret
= mlt_service_connect_producer( &this->parent
, producer
, a_track
);
120 mlt_properties properties
= MLT_TRANSITION_PROPERTIES( this );
121 this->producer
= producer
;
122 mlt_properties_set_int( properties
, "a_track", a_track
);
123 mlt_properties_set_int( properties
, "b_track", b_track
);
128 /** Set the starting and ending time for when the transition is active.
130 * \public \memberof mlt_transition_s
131 * \param this a transition
132 * \param in the starting time
133 * \param out the ending time
136 void mlt_transition_set_in_and_out( mlt_transition
this, mlt_position in
, mlt_position out
)
138 mlt_properties properties
= MLT_TRANSITION_PROPERTIES( this );
139 mlt_properties_set_position( properties
, "in", in
);
140 mlt_properties_set_position( properties
, "out", out
);
143 /** Get the index of the a track.
145 * \public \memberof mlt_transition_s
146 * \param this a transition
147 * \return the 0-based index of the track of the first producer
150 int mlt_transition_get_a_track( mlt_transition
this )
152 return mlt_properties_get_int( MLT_TRANSITION_PROPERTIES( this ), "a_track" );
155 /** Get the index of the b track.
157 * \public \memberof mlt_transition_s
158 * \param this a transition
159 * \return the 0-based index of the track of the second producer
162 int mlt_transition_get_b_track( mlt_transition
this )
164 return mlt_properties_get_int( MLT_TRANSITION_PROPERTIES( this ), "b_track" );
167 /** Get the in point.
169 * \public \memberof mlt_transition_s
170 * \param this a transition
171 * \return the starting time
174 mlt_position
mlt_transition_get_in( mlt_transition
this )
176 return mlt_properties_get_position( MLT_TRANSITION_PROPERTIES( this ), "in" );
179 /** Get the out point.
181 * \public \memberof mlt_transition_s
182 * \param this a transition
183 * \return the ending time
186 mlt_position
mlt_transition_get_out( mlt_transition
this )
188 return mlt_properties_get_position( MLT_TRANSITION_PROPERTIES( this ), "out" );
191 /** Process the frame.
193 * If we have no process method (unlikely), we simply return the a_frame unmolested.
195 * \public \memberof mlt_transition_s
196 * \param this a transition
197 * \param a_frame a frame from the first producer
198 * \param b_frame a frame from the second producer
202 mlt_frame
mlt_transition_process( mlt_transition
this, mlt_frame a_frame
, mlt_frame b_frame
)
204 if ( this->process
== NULL
)
207 return this->process( this, a_frame
, b_frame
);
210 /** Get a frame from this transition.
212 The logic is complex here. A transition is typically applied to frames on the a and
213 b tracks specified in the connect method above and only if both contain valid info
214 for the transition type (this is either audio or image).
216 However, the fixed a_track may not always contain data of the correct type, eg:
218 +---------+ +-------+
219 |c1 | |c5 | <-- A(0,1) <-- B(0,2) <-- get frame
220 +---------+ +---------+-+-----+ | |
222 +----------+-----------+-+---------+ |
223 |c2 |c3 | <-----------------+
224 +----------+-------------+
226 During the overlap of c1 and c2, there is nothing for the A transition to do, so this
227 results in a no operation, but B is triggered. During the overlap of c2 and c3, again,
228 the A transition is inactive and because the B transition is pointing at track 0,
229 it too would be inactive. This isn't an ideal situation - it's better if the B
230 transition simply treats the frames from c3 as though they're the a track.
232 For this to work, we cache all frames coming from all tracks between the a and b
233 tracks. Before we process, we determine that the b frame contains someting of the
234 right type and then we determine which frame to use as the a frame (selecting a
235 matching frame from a_track to b_track - 1). If both frames contain data of the
236 correct type, we process the transition.
238 This method is invoked for each track and we return the cached frames as needed.
239 We clear the cache only when the requested frame is flagged as a 'last_track' frame.
241 * \private \memberof mlt_transition_s
242 * \param service a service
243 * \param[out] frame a frame by reference
244 * \param index 0-based track index
245 * \return true on error
248 static int transition_get_frame( mlt_service service
, mlt_frame_ptr frame
, int index
)
251 mlt_transition
this = service
->child
;
253 mlt_properties properties
= MLT_TRANSITION_PROPERTIES( this );
255 int accepts_blanks
= mlt_properties_get_int( properties
, "accepts_blanks" );
256 int a_track
= mlt_properties_get_int( properties
, "a_track" );
257 int b_track
= mlt_properties_get_int( properties
, "b_track" );
258 mlt_position in
= mlt_properties_get_position( properties
, "in" );
259 mlt_position out
= mlt_properties_get_position( properties
, "out" );
260 int always_active
= mlt_properties_get_int( properties
, "always_active" );
261 int type
= mlt_properties_get_int( properties
, "_transition_type" );
262 int reverse_order
= 0;
264 // Ensure that we have the correct order
265 if ( a_track
> b_track
)
269 b_track
= mlt_properties_get_int( properties
, "a_track" );
272 // Only act on this operation once per multitrack iteration from the tractor
277 int a_frame
= a_track
;
278 int b_frame
= b_track
;
279 mlt_position position
;
280 int ( *invalid
)( mlt_frame
) = type
== 1 ? mlt_frame_is_test_card
: mlt_frame_is_test_audio
;
282 // Initialise temporary store
283 if ( this->frames
== NULL
)
284 this->frames
= calloc( sizeof( mlt_frame
), b_track
+ 1 );
286 // Get all frames between a and b
287 for( i
= a_track
; i
<= b_track
; i
++ )
288 mlt_service_get_frame( this->producer
, &this->frames
[ i
], i
);
290 // We're holding these frames until the last_track frame property is received
293 // When we need to locate the a_frame
298 // Some transitions (esp. audio) may accept blank frames
299 active
= accepts_blanks
;
301 // If we're not active then...
304 // Hunt for the a_frame
305 while( a_frame
<= b_frame
&& invalid( this->frames
[ a_frame
] ) )
308 // Determine if we're active now
309 active
= a_frame
!= b_frame
&& !invalid( this->frames
[ b_frame
] );
314 fprintf( stderr
, "invalid transition type\n" );
318 // Now handle the non-always active case
319 if ( active
&& !always_active
)
321 // For non-always-active transitions, we need the current position of the a frame
322 position
= mlt_frame_get_position( this->frames
[ a_frame
] );
324 // If a is in range, we're active
325 active
= position
>= in
&& position
<= out
;
328 // Finally, process the a and b frames
331 mlt_frame a_frame_ptr
= this->frames
[ !reverse_order ? a_frame
: b_frame
];
332 mlt_frame b_frame_ptr
= this->frames
[ !reverse_order ? b_frame
: a_frame
];
333 int a_hide
= mlt_properties_get_int( MLT_FRAME_PROPERTIES( a_frame_ptr
), "hide" );
334 int b_hide
= mlt_properties_get_int( MLT_FRAME_PROPERTIES( b_frame_ptr
), "hide" );
335 if ( !( a_hide
& type
) && !( b_hide
& type
) )
337 // Process the transition
338 *frame
= mlt_transition_process( this, a_frame_ptr
, b_frame_ptr
);
340 // We need to ensure that the tractor doesn't consider this frame for output
341 if ( *frame
== a_frame_ptr
)
346 mlt_properties_set_int( MLT_FRAME_PROPERTIES( a_frame_ptr
), "hide", a_hide
);
347 mlt_properties_set_int( MLT_FRAME_PROPERTIES( b_frame_ptr
), "hide", b_hide
);
352 // Obtain the frame from the cache or the producer we're attached to
353 if ( index
>= a_track
&& index
<= b_track
)
354 *frame
= this->frames
[ index
];
356 error
= mlt_service_get_frame( this->producer
, frame
, index
);
358 // Determine if that was the last track
359 this->held
= !mlt_properties_get_int( MLT_FRAME_PROPERTIES( *frame
), "last_track" );
364 /** Close and destroy the transition.
366 * \public \memberof mlt_transition_s
367 * \param this a transition
370 void mlt_transition_close( mlt_transition
this )
372 if ( this != NULL
&& mlt_properties_dec_ref( MLT_TRANSITION_PROPERTIES( this ) ) <= 0 )
374 this->parent
.close
= NULL
;
375 if ( this->close
!= NULL
)
381 mlt_service_close( &this->parent
);
382 free( this->frames
);