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_frame( 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 = 0.5;
  46         if ( mlt_properties_get( b_props, "audio.mix" ) != NULL )
  47                 mix = mlt_properties_get_double( b_props, "audio.mix" );
  48         mlt_frame_mix_audio( frame, b_frame, mix, buffer, format, frequency, channels, samples );
  49
  50         // Push the b_frame back on for get_image
  51         mlt_frame_push_frame( frame, b_frame );
  52
  53         return 0;
  54 }
  55
  56
  57 /** Mix transition processing.
  58 */
  59
  60 static mlt_frame transition_process( mlt_transition this, mlt_frame a_frame, mlt_frame b_frame )
  61 {
  62         mlt_properties properties = mlt_transition_properties( this );
  63         mlt_properties b_props = mlt_frame_properties( b_frame );
  64
  65         // Only if mix is specified, otherwise a producer may set the mix
  66         if ( mlt_properties_get( properties, "mix" ) != NULL )
  67         {
  68                 // A negative means crossfade
  69                 if ( mlt_properties_get_double( properties, "mix" ) < 0 )
  70                 {
  71                         // Determine the time position of this frame in the transition duration
  72                         mlt_position in = mlt_transition_get_in( this );
  73                         mlt_position out = mlt_transition_get_out( this );
  74                         mlt_position time = mlt_frame_get_position( b_frame );
  75                         double mix = ( double )( time - in ) / ( double )( out - in + 1 );
  76                         mlt_properties_set_double( b_props, "audio.mix", mix );
  77                 }
  78                 else
  79                         mlt_properties_set_double( b_props, "audio.mix", mlt_properties_get_double( properties, "mix" ) );
  80         }
  81
  82         // Backup the original get_audio (it's still needed)
  83         mlt_properties_set_data( mlt_frame_properties( a_frame ), "mix.get_audio", a_frame->get_audio, 0, NULL, NULL );
  84
  85         // Override the get_audio method
  86         a_frame->get_audio = transition_get_audio;
  87
  88         mlt_frame_push_frame( a_frame, b_frame );
  89
  90         return a_frame;
  91 }
  92
  93 /** Constructor for the transition.
  94 */
  95
  96 mlt_transition transition_mix_init( char *arg )
  97 {
  98         mlt_transition this = calloc( sizeof( struct mlt_transition_s ), 1 );
  99         if ( this != NULL && mlt_transition_init( this, NULL ) == 0 )
 100         {
 101                 this->process = transition_process;
 102                 if ( arg != NULL )
 103                         mlt_properties_set_double( mlt_transition_properties( this ), "mix", atof( arg ) );
 104         }
 105         return this;
 106 }
 107