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
  56         mlt_frame_mix_audio( frame, b_frame, mix_start, mix_end, buffer, format, frequency, channels, samples );
  57
  58         return 0;
  59 }
  60
  61
  62 /** Mix transition processing.
  63 */
  64
  65 static mlt_frame transition_process( mlt_transition this, mlt_frame a_frame, mlt_frame b_frame )
  66 {
  67         mlt_properties properties = MLT_TRANSITION_PROPERTIES( this );
  68         mlt_properties b_props = MLT_FRAME_PROPERTIES( b_frame );
  69
  70         // Only if mix is specified, otherwise a producer may set the mix
  71         if ( mlt_properties_get( properties, "start" ) != NULL )
  72         {
  73                 // Determine the time position of this frame in the transition duration
  74                 mlt_position in = mlt_transition_get_in( this );
  75                 mlt_position out = mlt_transition_get_out( this );
  76                 mlt_position time = mlt_frame_get_position( b_frame );
  77                 double mix = ( double )( time - in ) / ( double )( out - in + 1 );
  78
  79                 // If there is an end mix level adjust mix to the range
  80                 if ( mlt_properties_get( properties, "end" ) != NULL )
  81                 {
  82                         double start = mlt_properties_get_double( properties, "start" );
  83                         double end = mlt_properties_get_double( properties, "end" );
  84                         mix = start + ( end - start ) * mix;
  85                 }
  86                 // A negative means total crossfade (uses position)
  87                 else if ( mlt_properties_get_double( properties, "start" ) >= 0 )
  88                 {
  89                         // Otherwise, start/constructor is a constant mix level
  90                     mix = mlt_properties_get_double( properties, "start" );
  91                 }
  92
  93                 // Finally, set the mix property on the frame
  94                 mlt_properties_set_double( b_props, "audio.mix", mix );
  95
  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" ) );
  99
 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" ) );
 102
 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" ) );
 105
 106                 mlt_properties_set_double( b_props, "audio.reverse", mlt_properties_get_double( properties, "reverse" ) );
 107         }
 108
 109         // Ensure that the tractor knows this isn't test audio...
 110         if ( mlt_properties_get_int( MLT_FRAME_PROPERTIES( a_frame ), "test_audio" ) )
 111         {
 112                 mlt_properties_set_int( MLT_FRAME_PROPERTIES( a_frame ), "test_audio", 0 );
 113                 mlt_properties_set_int( MLT_FRAME_PROPERTIES( a_frame ), "silent_audio", 1 );
 114         }
 115
 116         // Backup the original get_audio (it's still needed)
 117         mlt_properties_set_data( MLT_FRAME_PROPERTIES( a_frame ), "mix.get_audio", a_frame->get_audio, 0, NULL, NULL );
 118
 119         // Override the get_audio method
 120         a_frame->get_audio = transition_get_audio;
 121
 122         mlt_frame_push_audio( a_frame, b_frame );
 123
 124         return a_frame;
 125 }
 126
 127 /** Constructor for the transition.
 128 */
 129
 130 mlt_transition transition_mix_init( char *arg )
 131 {
 132         mlt_transition this = calloc( sizeof( struct mlt_transition_s ), 1 );
 133         if ( this != NULL && mlt_transition_init( this, NULL ) == 0 )
 134         {
 135                 this->process = transition_process;
 136                 if ( arg != NULL )
 137                         mlt_properties_set_double( MLT_TRANSITION_PROPERTIES( this ), "start", atof( arg ) );
 138                 mlt_properties_set_int( MLT_TRANSITION_PROPERTIES( this ), "_accepts_blanks", 1 );
 139         }
 140         return this;
 141 }
 142