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 b frame from the stack
34 mlt_frame b_frame
= mlt_frame_pop_audio( frame
);
36 // Get the properties of the b frame
37 mlt_properties b_props
= MLT_FRAME_PROPERTIES( b_frame
);
39 double mix_start
= 0.5, mix_end
= 0.5;
40 if ( mlt_properties_get( b_props
, "audio.previous_mix" ) != NULL
)
41 mix_start
= mlt_properties_get_double( b_props
, "audio.previous_mix" );
42 if ( mlt_properties_get( b_props
, "audio.mix" ) != NULL
)
43 mix_end
= mlt_properties_get_double( b_props
, "audio.mix" );
44 if ( mlt_properties_get_int( b_props
, "audio.reverse" ) )
46 mix_start
= 1 - mix_start
;
47 mix_end
= 1 - mix_end
;
50 mlt_frame_mix_audio( frame
, b_frame
, mix_start
, mix_end
, buffer
, format
, frequency
, channels
, samples
);
56 /** Mix transition processing.
59 static mlt_frame
transition_process( mlt_transition
this, mlt_frame a_frame
, mlt_frame b_frame
)
61 mlt_properties properties
= MLT_TRANSITION_PROPERTIES( this );
62 mlt_properties b_props
= MLT_FRAME_PROPERTIES( b_frame
);
64 // Only if mix is specified, otherwise a producer may set the mix
65 if ( mlt_properties_get( properties
, "start" ) != NULL
)
67 // Determine the time position of this frame in the transition duration
68 mlt_properties props
= mlt_properties_get_data( MLT_FRAME_PROPERTIES( b_frame
), "_producer", NULL
);
69 int always_active
= mlt_properties_get_int( MLT_TRANSITION_PROPERTIES( this ), "always_active" );
70 mlt_position in
= !always_active ?
mlt_transition_get_in( this ) : mlt_properties_get_int( props
, "in" );
71 mlt_position out
= !always_active ?
mlt_transition_get_out( this ) : mlt_properties_get_int( props
, "out" );
72 int length
= mlt_properties_get_int( MLT_TRANSITION_PROPERTIES( this ), "length" );
73 mlt_position time
= !always_active ?
mlt_frame_get_position( b_frame
) : mlt_properties_get_int( props
, "_frame" );
74 double mix
= ( double )( time
- in
) / ( double )( out
- in
+ 1 );
76 // TODO: Check the logic here - shouldn't we be computing current and next mixing levels in all cases?
79 // If there is an end mix level adjust mix to the range
80 if ( mlt_properties_get( properties
, "end" ) != NULL
)
82 double start
= mlt_properties_get_double( properties
, "start" );
83 double end
= mlt_properties_get_double( properties
, "end" );
84 mix
= start
+ ( end
- start
) * mix
;
86 // A negative means total crossfade (uses position)
87 else if ( mlt_properties_get_double( properties
, "start" ) >= 0 )
89 // Otherwise, start/constructor is a constant mix level
90 mix
= mlt_properties_get_double( properties
, "start" );
93 // Finally, set the mix property on the frame
94 mlt_properties_set_double( b_props
, "audio.mix", mix
);
96 // Initialise transition previous mix value to prevent an inadvertant jump from 0
97 if ( mlt_properties_get( properties
, "previous_mix" ) == NULL
)
98 mlt_properties_set_double( properties
, "previous_mix", mlt_properties_get_double( b_props
, "audio.mix" ) );
100 // Tell b frame what the previous mix level was
101 mlt_properties_set_double( b_props
, "audio.previous_mix", mlt_properties_get_double( properties
, "previous_mix" ) );
103 // Save the current mix level for the next iteration
104 mlt_properties_set_double( properties
, "previous_mix", mlt_properties_get_double( b_props
, "audio.mix" ) );
106 mlt_properties_set_double( b_props
, "audio.reverse", mlt_properties_get_double( properties
, "reverse" ) );
110 double level
= mlt_properties_get_double( properties
, "start" );
111 double mix_start
= level
;
112 double mix_end
= mix_start
;
113 double mix_increment
= 1.0 / length
;
114 if ( time
- in
< length
)
116 mix_start
= mix_start
* ( ( double )( time
- in
) / length
);
117 mix_end
= mix_start
+ mix_increment
;
119 else if ( time
> out
- length
)
121 mix_end
= mix_start
* ( ( double )( out
- time
- in
) / length
);
122 mix_start
= mix_end
- mix_increment
;
125 mix_start
= mix_start
< 0 ?
0 : mix_start
> level ? level
: mix_start
;
126 mix_end
= mix_end
< 0 ?
0 : mix_end
> level ? level
: mix_end
;
127 mlt_properties_set_double( b_props
, "audio.previous_mix", mix_start
);
128 mlt_properties_set_double( b_props
, "audio.mix", mix_end
);
132 // Override the get_audio method
133 mlt_frame_push_audio( a_frame
, b_frame
);
134 mlt_frame_push_audio( a_frame
, transition_get_audio
);
139 /** Constructor for the transition.
142 mlt_transition
transition_mix_init( char *arg
)
144 mlt_transition
this = calloc( sizeof( struct mlt_transition_s
), 1 );
145 if ( this != NULL
&& mlt_transition_init( this, NULL
) == 0 )
147 this->process
= transition_process
;
149 mlt_properties_set_double( MLT_TRANSITION_PROPERTIES( this ), "start", atof( arg
) );
150 // Inform apps and framework that this is an audio only transition
151 mlt_properties_set_int( MLT_TRANSITION_PROPERTIES( this ), "_transition_type", 2 );