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 b frame from the stack
  34         mlt_frame b_frame = mlt_frame_pop_audio( frame );
  35
  36         // Get the properties of the b frame
  37         mlt_properties b_props = MLT_FRAME_PROPERTIES( b_frame );
  38
  39         double mix_start = 0.5, mix_end = 0.5;
  40         if ( mlt_properties_get( b_props, "audio.previous_mix" ) != NULL )
  41                 mix_start = mlt_properties_get_double( b_props, "audio.previous_mix" );
  42         if ( mlt_properties_get( b_props, "audio.mix" ) != NULL )
  43                 mix_end = mlt_properties_get_double( b_props, "audio.mix" );
  44         if ( mlt_properties_get_int( b_props, "audio.reverse" ) )
  45         {
  46                 mix_start = 1 - mix_start;
  47                 mix_end = 1 - mix_end;
  48         }
  49
  50         mlt_frame_mix_audio( frame, b_frame, mix_start, mix_end, buffer, format, frequency, channels, samples );
  51
  52         return 0;
  53 }
  54
  55
  56 /** Mix transition processing.
  57 */
  58
  59 static mlt_frame transition_process( mlt_transition this, mlt_frame a_frame, mlt_frame b_frame )
  60 {
  61         mlt_properties properties = MLT_TRANSITION_PROPERTIES( this );
  62         mlt_properties b_props = MLT_FRAME_PROPERTIES( b_frame );
  63
  64         // Only if mix is specified, otherwise a producer may set the mix
  65         if ( mlt_properties_get( properties, "start" ) != NULL )
  66         {
  67                 // Determine the time position of this frame in the transition duration
  68                 mlt_properties props = mlt_properties_get_data( MLT_FRAME_PROPERTIES( b_frame ), "_producer", NULL );
  69                 int always_active = mlt_properties_get_int(  MLT_TRANSITION_PROPERTIES( this ), "always_active" );
  70                 mlt_position in = !always_active ? mlt_transition_get_in( this ) : mlt_properties_get_int( props, "in" );
  71                 mlt_position out = !always_active ? mlt_transition_get_out( this ) : mlt_properties_get_int( props, "out" );
  72                 int length = mlt_properties_get_int(  MLT_TRANSITION_PROPERTIES( this ), "length" );
  73                 mlt_position time = !always_active ? mlt_frame_get_position( b_frame ) : mlt_properties_get_int( props, "_frame" );
  74                 double mix = ( double )( time - in ) / ( double )( out - in + 1 );
  75
  76                 // TODO: Check the logic here - shouldn't we be computing current and next mixing levels in all cases?
  77                 if ( length == 0 )
  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                 else
 109                 {
 110                         double level = mlt_properties_get_double( properties, "start" );
 111                         double mix_start = level;
 112                         double mix_end = mix_start;
 113                         double mix_increment = 1.0 / length;
 114                         if ( time - in < length )
 115                         {
 116                                 mix_start = mix_start * ( ( double )( time - in ) / length );
 117                                 mix_end = mix_start + mix_increment;
 118                         }
 119                         else if ( time > out - length )
 120                         {
 121                                 mix_end = mix_start * ( ( double )( out - time - in ) / length );
 122                                 mix_start = mix_end - mix_increment;
 123                         }
 124
 125                         mix_start = mix_start < 0 ? 0 : mix_start > level ? level : mix_start;
 126                         mix_end = mix_end < 0 ? 0 : mix_end > level ? level : mix_end;
 127                         mlt_properties_set_double( b_props, "audio.previous_mix", mix_start );
 128                         mlt_properties_set_double( b_props, "audio.mix", mix_end );
 129                 }
 130         }
 131
 132         // Override the get_audio method
 133         mlt_frame_push_audio( a_frame, b_frame );
 134         mlt_frame_push_audio( a_frame, transition_get_audio );
 135
 136         return a_frame;
 137 }
 138
 139 /** Constructor for the transition.
 140 */
 141
 142 mlt_transition transition_mix_init( char *arg )
 143 {
 144         mlt_transition this = calloc( sizeof( struct mlt_transition_s ), 1 );
 145         if ( this != NULL && mlt_transition_init( this, NULL ) == 0 )
 146         {
 147                 this->process = transition_process;
 148                 if ( arg != NULL )
 149                         mlt_properties_set_double( MLT_TRANSITION_PROPERTIES( this ), "start", atof( arg ) );
 150                 // Inform apps and framework that this is an audio only transition
 151                 mlt_properties_set_int( MLT_TRANSITION_PROPERTIES( this ), "_transition_type", 2 );
 152         }
 153         return this;
 154 }
 155