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
);
37 mlt_transition effect
= mlt_frame_pop_audio( frame
);
39 // Get the properties of the b frame
40 mlt_properties b_props
= MLT_FRAME_PROPERTIES( b_frame
);
42 if ( mlt_properties_get_int( MLT_TRANSITION_PROPERTIES( effect
), "combine" ) == 0 )
44 double mix_start
= 0.5, mix_end
= 0.5;
45 if ( mlt_properties_get( b_props
, "audio.previous_mix" ) != NULL
)
46 mix_start
= mlt_properties_get_double( b_props
, "audio.previous_mix" );
47 if ( mlt_properties_get( b_props
, "audio.mix" ) != NULL
)
48 mix_end
= mlt_properties_get_double( b_props
, "audio.mix" );
49 if ( mlt_properties_get_int( b_props
, "audio.reverse" ) )
51 mix_start
= 1 - mix_start
;
52 mix_end
= 1 - mix_end
;
55 mlt_frame_mix_audio( frame
, b_frame
, mix_start
, mix_end
, buffer
, format
, frequency
, channels
, samples
);
59 mlt_frame_combine_audio( frame
, b_frame
, buffer
, format
, frequency
, channels
, samples
);
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_properties props
= mlt_properties_get_data( MLT_FRAME_PROPERTIES( b_frame
), "_producer", NULL
);
79 int always_active
= mlt_properties_get_int( MLT_TRANSITION_PROPERTIES( this ), "always_active" );
80 mlt_position in
= !always_active ?
mlt_transition_get_in( this ) : mlt_properties_get_int( props
, "in" );
81 mlt_position out
= !always_active ?
mlt_transition_get_out( this ) : mlt_properties_get_int( props
, "out" );
82 int length
= mlt_properties_get_int( MLT_TRANSITION_PROPERTIES( this ), "length" );
83 mlt_position time
= !always_active ?
mlt_frame_get_position( b_frame
) : mlt_properties_get_int( props
, "_frame" );
84 double mix
= ( double )( time
- in
) / ( double )( out
- in
+ 1 );
86 // TODO: Check the logic here - shouldn't we be computing current and next mixing levels in all cases?
89 // If there is an end mix level adjust mix to the range
90 if ( mlt_properties_get( properties
, "end" ) != NULL
)
92 double start
= mlt_properties_get_double( properties
, "start" );
93 double end
= mlt_properties_get_double( properties
, "end" );
94 mix
= start
+ ( end
- start
) * mix
;
96 // A negative means total crossfade (uses position)
97 else if ( mlt_properties_get_double( properties
, "start" ) >= 0 )
99 // Otherwise, start/constructor is a constant mix level
100 mix
= mlt_properties_get_double( properties
, "start" );
103 // Finally, set the mix property on the frame
104 mlt_properties_set_double( b_props
, "audio.mix", mix
);
106 // Initialise transition previous mix value to prevent an inadvertant jump from 0
107 if ( mlt_properties_get( properties
, "previous_mix" ) == NULL
)
108 mlt_properties_set_double( properties
, "previous_mix", mlt_properties_get_double( b_props
, "audio.mix" ) );
110 // Tell b frame what the previous mix level was
111 mlt_properties_set_double( b_props
, "audio.previous_mix", mlt_properties_get_double( properties
, "previous_mix" ) );
113 // Save the current mix level for the next iteration
114 mlt_properties_set_double( properties
, "previous_mix", mlt_properties_get_double( b_props
, "audio.mix" ) );
116 mlt_properties_set_double( b_props
, "audio.reverse", mlt_properties_get_double( properties
, "reverse" ) );
120 double level
= mlt_properties_get_double( properties
, "start" );
121 double mix_start
= level
;
122 double mix_end
= mix_start
;
123 double mix_increment
= 1.0 / length
;
124 if ( time
- in
< length
)
126 mix_start
= mix_start
* ( ( double )( time
- in
) / length
);
127 mix_end
= mix_start
+ mix_increment
;
129 else if ( time
> out
- length
)
131 mix_end
= mix_start
* ( ( double )( out
- time
- in
) / length
);
132 mix_start
= mix_end
- mix_increment
;
135 mix_start
= mix_start
< 0 ?
0 : mix_start
> level ? level
: mix_start
;
136 mix_end
= mix_end
< 0 ?
0 : mix_end
> level ? level
: mix_end
;
137 mlt_properties_set_double( b_props
, "audio.previous_mix", mix_start
);
138 mlt_properties_set_double( b_props
, "audio.mix", mix_end
);
142 // Override the get_audio method
143 mlt_frame_push_audio( a_frame
, this );
144 mlt_frame_push_audio( a_frame
, b_frame
);
145 mlt_frame_push_audio( a_frame
, transition_get_audio
);
150 /** Constructor for the transition.
153 mlt_transition
transition_mix_init( char *arg
)
155 mlt_transition
this = calloc( sizeof( struct mlt_transition_s
), 1 );
156 if ( this != NULL
&& mlt_transition_init( this, NULL
) == 0 )
158 this->process
= transition_process
;
160 mlt_properties_set_double( MLT_TRANSITION_PROPERTIES( this ), "start", atof( arg
) );
161 // Inform apps and framework that this is an audio only transition
162 mlt_properties_set_int( MLT_TRANSITION_PROPERTIES( this ), "_transition_type", 2 );