2 * transition_mix.c -- mix two audio streams
3 * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
4 * Author: Dan Dennedy <dan@dennedy.org>
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.
21 #include "transition_mix.h"
22 #include <framework/mlt_frame.h>
31 static int transition_get_audio( mlt_frame frame
, int16_t **buffer
, mlt_audio_format
*format
, int *frequency
, int *channels
, int *samples
)
33 // Get the properties of the a frame
34 mlt_properties a_props
= mlt_frame_properties( frame
);
36 // Get the b frame from the stack
37 mlt_frame b_frame
= mlt_frame_pop_frame( frame
);
39 // Get the properties of the b frame
40 mlt_properties b_props
= mlt_frame_properties( b_frame
);
42 // Restore the original get_audio
43 frame
->get_audio
= mlt_properties_get_data( a_props
, "mix.get_audio", NULL
);
45 double mix
= mlt_properties_get_double( b_props
, "audio.mix" );
46 mlt_frame_mix_audio( frame
, b_frame
, mix
, buffer
, format
, frequency
, channels
, samples
);
48 // Push the b_frame back on for get_image
49 mlt_frame_push_frame( frame
, b_frame
);
55 /** Mix transition processing.
58 static mlt_frame
transition_process( mlt_transition
this, mlt_frame a_frame
, mlt_frame b_frame
)
60 mlt_properties properties
= mlt_transition_properties( this );
61 mlt_properties b_props
= mlt_frame_properties( b_frame
);
63 // Only if mix is specified, otherwise a producer may set the mix
64 if ( mlt_properties_get( properties
, "mix" ) != NULL
)
66 // A negative means crossfade
67 if ( mlt_properties_get_double( properties
, "mix" ) < 0 )
69 // Determine the time position of this frame in the transition duration
70 mlt_position in
= mlt_transition_get_in( this );
71 mlt_position out
= mlt_transition_get_out( this );
72 mlt_position time
= mlt_frame_get_position( b_frame
);
73 double mix
= ( double )( time
- in
) / ( double )( out
- in
+ 1 );
74 mlt_properties_set_double( b_props
, "audio.mix", mix
);
77 mlt_properties_set_double( b_props
, "audio.mix", mlt_properties_get_double( properties
, "mix" ) );
80 // Backup the original get_audio (it's still needed)
81 mlt_properties_set_data( mlt_frame_properties( a_frame
), "mix.get_audio", a_frame
->get_audio
, 0, NULL
, NULL
);
83 // Override the get_audio method
84 a_frame
->get_audio
= transition_get_audio
;
86 mlt_frame_push_frame( a_frame
, b_frame
);
91 /** Constructor for the transition.
94 mlt_transition
transition_mix_init( char *arg
)
96 mlt_transition
this = calloc( sizeof( struct mlt_transition_s
), 1 );
97 if ( this != NULL
&& mlt_transition_init( this, NULL
) == 0 )
99 this->process
= transition_process
;
101 mlt_properties_set_double( mlt_transition_properties( this ), "mix", atof( arg
) );