2 * mlt_transition.c -- abstraction for all transition services
3 * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
4 * Author: Charles Yates <charles.yates@pandora.be>
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * This library 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 GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 #include "mlt_transition.h"
22 #include "mlt_frame.h"
28 /** Forward references.
31 static int transition_get_frame( mlt_service
this, mlt_frame_ptr frame
, int index
);
36 int mlt_transition_init( mlt_transition
this, void *child
)
38 mlt_service service
= &this->parent
;
39 memset( this, 0, sizeof( struct mlt_transition_s
) );
41 if ( mlt_service_init( service
, this ) == 0 )
43 mlt_properties properties
= MLT_TRANSITION_PROPERTIES( this );
45 service
->get_frame
= transition_get_frame
;
46 service
->close
= ( mlt_destructor
)mlt_transition_close
;
47 service
->close_object
= this;
49 mlt_properties_set_position( properties
, "in", 0 );
50 mlt_properties_set_position( properties
, "out", 0 );
51 mlt_properties_set_int( properties
, "a_track", 0 );
52 mlt_properties_set_int( properties
, "b_track", 1 );
59 /** Create a new transition.
62 mlt_transition
mlt_transition_new( )
64 mlt_transition
this = calloc( 1, sizeof( struct mlt_transition_s
) );
66 mlt_transition_init( this, NULL
);
70 /** Get the service associated to the transition.
73 mlt_service
mlt_transition_service( mlt_transition
this )
75 return this != NULL ?
&this->parent
: NULL
;
78 /** Get the properties interface.
81 mlt_properties
mlt_transition_properties( mlt_transition
this )
83 return MLT_TRANSITION_PROPERTIES( this );
86 /** Connect this transition with a producers a and b tracks.
89 int mlt_transition_connect( mlt_transition
this, mlt_service producer
, int a_track
, int b_track
)
91 int ret
= mlt_service_connect_producer( &this->parent
, producer
, a_track
);
94 mlt_properties properties
= MLT_TRANSITION_PROPERTIES( this );
95 this->producer
= producer
;
96 mlt_properties_set_int( properties
, "a_track", a_track
);
97 mlt_properties_set_int( properties
, "b_track", b_track
);
102 /** Set the in and out points.
105 void mlt_transition_set_in_and_out( mlt_transition
this, mlt_position in
, mlt_position out
)
107 mlt_properties properties
= MLT_TRANSITION_PROPERTIES( this );
108 mlt_properties_set_position( properties
, "in", in
);
109 mlt_properties_set_position( properties
, "out", out
);
112 /** Get the index of the a track.
115 int mlt_transition_get_a_track( mlt_transition
this )
117 return mlt_properties_get_int( MLT_TRANSITION_PROPERTIES( this ), "a_track" );
120 /** Get the index of the b track.
123 int mlt_transition_get_b_track( mlt_transition
this )
125 return mlt_properties_get_int( MLT_TRANSITION_PROPERTIES( this ), "b_track" );
128 /** Get the in point.
131 mlt_position
mlt_transition_get_in( mlt_transition
this )
133 return mlt_properties_get_position( MLT_TRANSITION_PROPERTIES( this ), "in" );
136 /** Get the out point.
139 mlt_position
mlt_transition_get_out( mlt_transition
this )
141 return mlt_properties_get_position( MLT_TRANSITION_PROPERTIES( this ), "out" );
144 /** Process the frame.
146 If we have no process method (unlikely), we simply return the a_frame unmolested.
149 mlt_frame
mlt_transition_process( mlt_transition
this, mlt_frame a_frame
, mlt_frame b_frame
)
151 if ( this->process
== NULL
)
154 return this->process( this, a_frame
, b_frame
);
157 /** Get a frame from this transition.
159 The logic is complex here. A transition is typically applied to frames on the a and
160 b tracks specified in the connect method above and only if both contain valid info
161 for the transition type (this is either audio or image).
163 However, the fixed a_track may not always contain data of the correct type, eg:
165 +---------+ +-------+
166 |c1 | |c5 | <-- A(0,1) <-- B(0,2) <-- get frame
167 +---------+ +---------+-+-----+ | |
169 +----------+-----------+-+---------+ |
170 |c2 |c3 | <-----------------+
171 +----------+-------------+
173 During the overlap of c1 and c2, there is nothing for the A transition to do, so this
174 results in a no operation, but B is triggered. During the overlap of c2 and c3, again,
175 the A transition is inactive and because the B transition is pointing at track 0,
176 it too would be inactive. This isn't an ideal situation - it's better if the B
177 transition simply treats the frames from c3 as though they're the a track.
179 For this to work, we cache all frames coming from all tracks between the a and b
180 tracks. Before we process, we determine that the b frame contains someting of the
181 right type and then we determine which frame to use as the a frame (selecting a
182 matching frame from a_track to b_track - 1). If both frames contain data of the
183 correct type, we process the transition.
185 This method is invoked for each track and we return the cached frames as needed.
186 We clear the cache only when the requested frame is flagged as a 'last_track' frame.
189 static int transition_get_frame( mlt_service service
, mlt_frame_ptr frame
, int index
)
192 mlt_transition
this = service
->child
;
194 mlt_properties properties
= MLT_TRANSITION_PROPERTIES( this );
196 int accepts_blanks
= mlt_properties_get_int( properties
, "accepts_blanks" );
197 int a_track
= mlt_properties_get_int( properties
, "a_track" );
198 int b_track
= mlt_properties_get_int( properties
, "b_track" );
199 mlt_position in
= mlt_properties_get_position( properties
, "in" );
200 mlt_position out
= mlt_properties_get_position( properties
, "out" );
201 int always_active
= mlt_properties_get_int( properties
, "always_active" );
202 int type
= mlt_properties_get_int( properties
, "_transition_type" );
203 int reverse_order
= 0;
205 // Ensure that we have the correct order
206 if ( a_track
> b_track
)
210 b_track
= mlt_properties_get_int( properties
, "a_track" );
213 // Only act on this operation once per multitrack iteration from the tractor
218 int a_frame
= a_track
;
219 int b_frame
= b_track
;
220 mlt_position position
;
221 int ( *invalid
)( mlt_frame
) = type
== 1 ? mlt_frame_is_test_card
: mlt_frame_is_test_audio
;
223 // Initialise temporary store
224 if ( this->frames
== NULL
)
225 this->frames
= calloc( sizeof( mlt_frame
), b_track
+ 1 );
227 // Get all frames between a and b
228 for( i
= a_track
; i
<= b_track
; i
++ )
229 mlt_service_get_frame( this->producer
, &this->frames
[ i
], i
);
231 // We're holding these frames until the last_track frame property is received
234 // When we need to locate the a_frame
239 // Some transitions (esp. audio) may accept blank frames
240 active
= accepts_blanks
;
242 // If we're not active then...
245 // Hunt for the a_frame
246 while( a_frame
<= b_frame
&& invalid( this->frames
[ a_frame
] ) )
249 // Determine if we're active now
250 active
= a_frame
!= b_frame
&& !invalid( this->frames
[ b_frame
] );
255 fprintf( stderr
, "invalid transition type\n" );
259 // Now handle the non-always active case
260 if ( active
&& !always_active
)
262 // For non-always-active transitions, we need the current position of the a frame
263 position
= mlt_frame_get_position( this->frames
[ a_frame
] );
265 // If a is in range, we're active
266 active
= position
>= in
&& position
<= out
;
269 // Finally, process the a and b frames
272 mlt_frame a_frame_ptr
= this->frames
[ !reverse_order ? a_frame
: b_frame
];
273 mlt_frame b_frame_ptr
= this->frames
[ !reverse_order ? b_frame
: a_frame
];
274 int a_hide
= mlt_properties_get_int( MLT_FRAME_PROPERTIES( a_frame_ptr
), "hide" );
275 int b_hide
= mlt_properties_get_int( MLT_FRAME_PROPERTIES( b_frame_ptr
), "hide" );
276 if ( !( a_hide
& type
) && !( b_hide
& type
) )
278 // Process the transition
279 *frame
= mlt_transition_process( this, a_frame_ptr
, b_frame_ptr
);
281 // We need to ensure that the tractor doesn't consider this frame for output
282 if ( *frame
== a_frame_ptr
)
287 mlt_properties_set_int( MLT_FRAME_PROPERTIES( a_frame_ptr
), "hide", a_hide
);
288 mlt_properties_set_int( MLT_FRAME_PROPERTIES( b_frame_ptr
), "hide", b_hide
);
293 // Obtain the frame from the cache or the producer we're attached to
294 if ( index
>= a_track
&& index
<= b_track
)
295 *frame
= this->frames
[ index
];
297 error
= mlt_service_get_frame( this->producer
, frame
, index
);
299 // Determine if that was the last track
300 this->held
= !mlt_properties_get_int( MLT_FRAME_PROPERTIES( *frame
), "last_track" );
305 /** Close the transition.
308 void mlt_transition_close( mlt_transition
this )
310 if ( this != NULL
&& mlt_properties_dec_ref( MLT_TRANSITION_PROPERTIES( this ) ) <= 0 )
312 this->parent
.close
= NULL
;
313 if ( this->close
!= NULL
)
319 mlt_service_close( &this->parent
);
320 free( this->frames
);