research.m1stereo.tv/gitweb/ - melted/blob - src/modules/core/transition_mix.c

   1 /*
   2  * transition_mix.c -- mix two audio streams
   3  * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
   4  * Author: Dan Dennedy <dan@dennedy.org>
   5  *
   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.
  10  *
  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.
  15  *
  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.
  19  */
  20
  21 #include "transition_mix.h"
  22 #include <framework/mlt_frame.h>
  23
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26
  27
  28 /** Get the audio.
  29 */
  30
  31 static int transition_get_audio( mlt_frame frame, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
  32 {
  33         // Get the properties of the a frame
  34         mlt_properties a_props = mlt_frame_properties( frame );
  35
  36         // Get the b frame from the stack
  37         mlt_frame b_frame = mlt_frame_pop_audio( frame );
  38
  39         // Get the properties of the b frame
  40         mlt_properties b_props = mlt_frame_properties( b_frame );
  41
  42         // Restore the original get_audio
  43         frame->get_audio = mlt_properties_get_data( a_props, "mix.get_audio", NULL );
  44
  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" ) )
  51         {
  52                 mix_start = 1 - mix_start;
  53                 mix_end = 1 - mix_end;
  54         }
  55         //fprintf( stderr, "transition_mix: previous %f current %f\n", mix_start, mix_end );
  56
  57         mlt_frame_mix_audio( frame, b_frame, mix_start, mix_end, buffer, format, frequency, channels, samples );
  58
  59         return 0;
  60 }
  61
  62
  63 /** Mix transition processing.
  64 */
  65
  66 static mlt_frame transition_process( mlt_transition this, mlt_frame a_frame, mlt_frame b_frame )
  67 {
  68         mlt_properties properties = mlt_transition_properties( this );
  69         mlt_properties b_props = mlt_frame_properties( b_frame );
  70
  71         // Only if mix is specified, otherwise a producer may set the mix
  72         if ( mlt_properties_get( properties, "start" ) != NULL )
  73         {
  74                 // Determine the time position of this frame in the transition duration
  75                 mlt_position in = mlt_transition_get_in( this );
  76                 mlt_position out = mlt_transition_get_out( this );
  77                 mlt_position time = mlt_frame_get_position( b_frame );
  78                 double mix = ( double )( time - in ) / ( double )( out - in + 1 );
  79
  80                 // If there is an end mix level adjust mix to the range
  81                 if ( mlt_properties_get( properties, "end" ) != NULL )
  82                 {
  83                         double start = mlt_properties_get_double( properties, "start" );
  84                         double end = mlt_properties_get_double( properties, "end" );
  85                         mix = start + ( end - start ) * mix;
  86                 }
  87                 // A negative means total crossfade (uses position)
  88                 else if ( mlt_properties_get_double( properties, "start" ) >= 0 )
  89                 {
  90                         // Otherwise, start/constructor is a constant mix level
  91                     mix = mlt_properties_get_double( properties, "start" );
  92                 }
  93
  94                 // Finally, set the mix property on the frame
  95                 mlt_properties_set_double( b_props, "audio.mix", mix );
  96
  97                 // Initialise transition previous mix value to prevent an inadvertant jump from 0
  98                 if ( mlt_properties_get( properties, "previous_mix" ) == NULL )
  99                         mlt_properties_set_double( properties, "previous_mix", mlt_properties_get_double( b_props, "audio.mix" ) );
 100
 101                 // Tell b frame what the previous mix level was
 102                 mlt_properties_set_double( b_props, "audio.previous_mix", mlt_properties_get_double( properties, "previous_mix" ) );
 103
 104                 // Save the current mix level for the next iteration
 105                 mlt_properties_set_double( properties, "previous_mix", mlt_properties_get_double( b_props, "audio.mix" ) );
 106
 107                 mlt_properties_set_double( b_props, "audio.reverse", mlt_properties_get_double( properties, "reverse" ) );
 108         }
 109
 110         // Backup the original get_audio (it's still needed)
 111         mlt_properties_set_data( mlt_frame_properties( a_frame ), "mix.get_audio", a_frame->get_audio, 0, NULL, NULL );
 112
 113         // Override the get_audio method
 114         a_frame->get_audio = transition_get_audio;
 115
 116         mlt_frame_push_audio( a_frame, b_frame );
 117
 118         return a_frame;
 119 }
 120
 121 /** Constructor for the transition.
 122 */
 123
 124 mlt_transition transition_mix_init( char *arg )
 125 {
 126         mlt_transition this = calloc( sizeof( struct mlt_transition_s ), 1 );
 127         if ( this != NULL && mlt_transition_init( this, NULL ) == 0 )
 128         {
 129                 this->process = transition_process;
 130                 if ( arg != NULL )
 131                         mlt_properties_set_double( mlt_transition_properties( this ), "start", atof( arg ) );
 132         }
 133         return this;
 134 }
 135