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 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 <framework/mlt_transition.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 mlt_position last_position
= mlt_properties_get_position( properties
, "_last_position" );
108 mlt_position current_position
= mlt_frame_get_position( b_frame
);
109 if ( mlt_properties_get( properties
, "_previous_mix" ) == NULL
110 || current_position
!= last_position
+ 1 )
111 mlt_properties_set_double( properties
, "_previous_mix", mix
);
113 // Tell b frame what the previous mix level was
114 mlt_properties_set_double( b_props
, "audio.previous_mix", mlt_properties_get_double( properties
, "_previous_mix" ) );
116 // Save the current mix level for the next iteration
117 mlt_properties_set_double( properties
, "_previous_mix", mlt_properties_get_double( b_props
, "audio.mix" ) );
119 mlt_properties_set_double( b_props
, "audio.reverse", mlt_properties_get_double( properties
, "reverse" ) );
123 double level
= mlt_properties_get_double( properties
, "start" );
124 double mix_start
= level
;
125 double mix_end
= mix_start
;
126 double mix_increment
= 1.0 / length
;
127 if ( time
- in
< length
)
129 mix_start
= mix_start
* ( ( double )( time
- in
) / length
);
130 mix_end
= mix_start
+ mix_increment
;
132 else if ( time
> out
- length
)
134 mix_end
= mix_start
* ( ( double )( out
- time
- in
) / length
);
135 mix_start
= mix_end
- mix_increment
;
138 mix_start
= mix_start
< 0 ?
0 : mix_start
> level ? level
: mix_start
;
139 mix_end
= mix_end
< 0 ?
0 : mix_end
> level ? level
: mix_end
;
140 mlt_properties_set_double( b_props
, "audio.previous_mix", mix_start
);
141 mlt_properties_set_double( b_props
, "audio.mix", mix_end
);
145 // Override the get_audio method
146 mlt_frame_push_audio( a_frame
, this );
147 mlt_frame_push_audio( a_frame
, b_frame
);
148 mlt_frame_push_audio( a_frame
, transition_get_audio
);
153 /** Constructor for the transition.
156 mlt_transition
transition_mix_init( mlt_profile profile
, mlt_service_type type
, const char *id
, char *arg
)
158 mlt_transition
this = calloc( sizeof( struct mlt_transition_s
), 1 );
159 if ( this != NULL
&& mlt_transition_init( this, NULL
) == 0 )
161 this->process
= transition_process
;
163 mlt_properties_set_double( MLT_TRANSITION_PROPERTIES( this ), "start", atof( arg
) );
164 // Inform apps and framework that this is an audio only transition
165 mlt_properties_set_int( MLT_TRANSITION_PROPERTIES( this ), "_transition_type", 2 );