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_start
= 0.5, mix_end
= 0.5;
46 if ( mlt_properties_get( b_props
, "audio.previous_mix" ) != NULL
)
47 mix_start
= mlt_properties_get_double( b_props
, "audio.previous_mix" );
48 if ( mlt_properties_get( b_props
, "audio.mix" ) != NULL
)
49 mix_end
= mlt_properties_get_double( b_props
, "audio.mix" );
50 if ( mlt_properties_get_int( b_props
, "audio.reverse" ) )
52 mix_start
= 1 - mix_start
;
53 mix_end
= 1 - mix_end
;
55 //fprintf( stderr, "transition_mix: previous %f current %f\n", mix_start, mix_end );
57 mlt_frame_mix_audio( frame
, b_frame
, mix_start
, mix_end
, buffer
, format
, frequency
, channels
, samples
);
59 // Push the b_frame back on for get_image
60 mlt_frame_push_frame( frame
, b_frame
);
66 /** Mix transition processing.
69 static mlt_frame
transition_process( mlt_transition
this, mlt_frame a_frame
, mlt_frame b_frame
)
71 mlt_properties properties
= mlt_transition_properties( this );
72 mlt_properties b_props
= mlt_frame_properties( b_frame
);
74 // Only if mix is specified, otherwise a producer may set the mix
75 if ( mlt_properties_get( properties
, "start" ) != NULL
)
77 // Determine the time position of this frame in the transition duration
78 mlt_position in
= mlt_transition_get_in( this );
79 mlt_position out
= mlt_transition_get_out( this );
80 mlt_position time
= mlt_frame_get_position( b_frame
);
81 double mix
= ( double )( time
- in
) / ( double )( out
- in
+ 1 );
83 // If there is an end mix level adjust mix to the range
84 if ( mlt_properties_get( properties
, "end" ) != NULL
)
86 double start
= mlt_properties_get_double( properties
, "start" );
87 double end
= mlt_properties_get_double( properties
, "end" );
88 mix
= start
+ ( end
- start
) * mix
;
90 // A negative means total crossfade (uses position)
91 else if ( mlt_properties_get_double( properties
, "start" ) >= 0 )
93 // Otherwise, start/constructor is a constant mix level
94 mix
= mlt_properties_get_double( properties
, "start" );
97 // Finally, set the mix property on the frame
98 mlt_properties_set_double( b_props
, "audio.mix", mix
);
100 // Initialise transition previous mix value to prevent an inadvertant jump from 0
101 if ( mlt_properties_get( properties
, "previous_mix" ) == NULL
)
102 mlt_properties_set_double( properties
, "previous_mix", mlt_properties_get_double( b_props
, "audio.mix" ) );
104 // Tell b frame what the previous mix level was
105 mlt_properties_set_double( b_props
, "audio.previous_mix", mlt_properties_get_double( properties
, "previous_mix" ) );
107 // Save the current mix level for the next iteration
108 mlt_properties_set_double( properties
, "previous_mix", mlt_properties_get_double( b_props
, "audio.mix" ) );
110 mlt_properties_set_double( b_props
, "audio.reverse", mlt_properties_get_double( properties
, "reverse" ) );
113 // Backup the original get_audio (it's still needed)
114 mlt_properties_set_data( mlt_frame_properties( a_frame
), "mix.get_audio", a_frame
->get_audio
, 0, NULL
, NULL
);
116 // Override the get_audio method
117 a_frame
->get_audio
= transition_get_audio
;
119 mlt_frame_push_frame( a_frame
, b_frame
);
124 /** Constructor for the transition.
127 mlt_transition
transition_mix_init( char *arg
)
129 mlt_transition
this = calloc( sizeof( struct mlt_transition_s
), 1 );
130 if ( this != NULL
&& mlt_transition_init( this, NULL
) == 0 )
132 this->process
= transition_process
;
134 mlt_properties_set_double( mlt_transition_properties( this ), "start", atof( arg
) );