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 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.
  10  *
  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.
  15  *
  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
  19  */
  20
  21 #include <framework/mlt_transition.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 effect
  37         mlt_transition effect = 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         if ( mlt_properties_get_int( MLT_TRANSITION_PROPERTIES( effect ), "combine" ) == 0 )
  43         {
  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" ) )
  50                 {
  51                         mix_start = 1 - mix_start;
  52                         mix_end = 1 - mix_end;
  53                 }
  54
  55                 mlt_frame_mix_audio( frame, b_frame, mix_start, mix_end, buffer, format, frequency, channels, samples );
  56         }
  57         else
  58         {
  59                 mlt_frame_combine_audio( frame, b_frame, buffer, format, frequency, channels, samples );
  60         }
  61
  62         return 0;
  63 }
  64
  65
  66 /** Mix transition processing.
  67 */
  68
  69 static mlt_frame transition_process( mlt_transition this, mlt_frame a_frame, mlt_frame b_frame )
  70 {
  71         mlt_properties properties = MLT_TRANSITION_PROPERTIES( this );
  72         mlt_properties b_props = MLT_FRAME_PROPERTIES( b_frame );
  73
  74         // Only if mix is specified, otherwise a producer may set the mix
  75         if ( mlt_properties_get( properties, "start" ) != NULL )
  76         {
  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 );
  85
  86                 // TODO: Check the logic here - shouldn't we be computing current and next mixing levels in all cases?
  87                 if ( length == 0 )
  88                 {
  89                         // If there is an end mix level adjust mix to the range
  90                         if ( mlt_properties_get( properties, "end" ) != NULL )
  91                         {
  92                                 double start = mlt_properties_get_double( properties, "start" );
  93                                 double end = mlt_properties_get_double( properties, "end" );
  94                                 mix = start + ( end - start ) * mix;
  95                         }
  96                         // A negative means total crossfade (uses position)
  97                         else if ( mlt_properties_get_double( properties, "start" ) >= 0 )
  98                         {
  99                                 // Otherwise, start/constructor is a constant mix level
 100                         mix = mlt_properties_get_double( properties, "start" );
 101                         }
 102
 103                         // Finally, set the mix property on the frame
 104                         mlt_properties_set_double( b_props, "audio.mix", mix );
 105
 106                         // Initialise transition previous mix value to prevent an inadvertant jump from 0
 107                         if ( mlt_properties_get( properties, "previous_mix" ) == NULL )
 108                                 mlt_properties_set_double( properties, "previous_mix", mlt_properties_get_double( b_props, "audio.mix" ) );
 109
 110                         // Tell b frame what the previous mix level was
 111                         mlt_properties_set_double( b_props, "audio.previous_mix", mlt_properties_get_double( properties, "previous_mix" ) );
 112
 113                         // Save the current mix level for the next iteration
 114                         mlt_properties_set_double( properties, "previous_mix", mlt_properties_get_double( b_props, "audio.mix" ) );
 115
 116                         mlt_properties_set_double( b_props, "audio.reverse", mlt_properties_get_double( properties, "reverse" ) );
 117                 }
 118                 else
 119                 {
 120                         double level = mlt_properties_get_double( properties, "start" );
 121                         double mix_start = level;
 122                         double mix_end = mix_start;
 123                         double mix_increment = 1.0 / length;
 124                         if ( time - in < length )
 125                         {
 126                                 mix_start = mix_start * ( ( double )( time - in ) / length );
 127                                 mix_end = mix_start + mix_increment;
 128                         }
 129                         else if ( time > out - length )
 130                         {
 131                                 mix_end = mix_start * ( ( double )( out - time - in ) / length );
 132                                 mix_start = mix_end - mix_increment;
 133                         }
 134
 135                         mix_start = mix_start < 0 ? 0 : mix_start > level ? level : mix_start;
 136                         mix_end = mix_end < 0 ? 0 : mix_end > level ? level : mix_end;
 137                         mlt_properties_set_double( b_props, "audio.previous_mix", mix_start );
 138                         mlt_properties_set_double( b_props, "audio.mix", mix_end );
 139                 }
 140         }
 141
 142         // Override the get_audio method
 143         mlt_frame_push_audio( a_frame, this );
 144         mlt_frame_push_audio( a_frame, b_frame );
 145         mlt_frame_push_audio( a_frame, transition_get_audio );
 146
 147         return a_frame;
 148 }
 149
 150 /** Constructor for the transition.
 151 */
 152
 153 mlt_transition transition_mix_init( mlt_profile profile, mlt_service_type type, const char *id, char *arg )
 154 {
 155         mlt_transition this = calloc( sizeof( struct mlt_transition_s ), 1 );
 156         if ( this != NULL && mlt_transition_init( this, NULL ) == 0 )
 157         {
 158                 this->process = transition_process;
 159                 if ( arg != NULL )
 160                         mlt_properties_set_double( MLT_TRANSITION_PROPERTIES( this ), "start", atof( arg ) );
 161                 // Inform apps and framework that this is an audio only transition
 162                 mlt_properties_set_int( MLT_TRANSITION_PROPERTIES( this ), "_transition_type", 2 );
 163         }
 164         return this;
 165 }
 166