research.m1stereo.tv/gitweb/ - melted/blob - src/modules/avformat/filter_avresample.c

   1 /*
   2  * filter_avresample.c -- adjust audio sample frequency
   3  * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
   4  * Author: Charles Yates <charles.yates@pandora.be>
   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 "filter_avresample.h"
  22
  23 #include <framework/mlt_frame.h>
  24
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28
  29 // ffmpeg Header files
  30 #include <ffmpeg/avformat.h>
  31
  32 /** Get the audio.
  33 */
  34
  35 static int resample_get_audio( mlt_frame frame, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
  36 {
  37         // Get the properties of the frame
  38         mlt_properties properties = mlt_frame_properties( frame );
  39
  40         // Get the filter service
  41         mlt_filter filter = mlt_frame_pop_audio( frame );
  42
  43         // Get the filter properties
  44         mlt_properties filter_properties = mlt_filter_properties( filter );
  45
  46         // Get the resample information
  47         int output_rate = mlt_properties_get_int( filter_properties, "frequency" );
  48         int16_t *sample_buffer = mlt_properties_get_data( filter_properties, "buffer", NULL );
  49
  50         // Obtain the resample context if it exists
  51         ReSampleContext *resample = mlt_properties_get_data( filter_properties, "audio_resample", NULL );
  52
  53         // Used to return number of channels in the source
  54         int channels_avail = *channels;
  55
  56         // Loop variable
  57         int i;
  58
  59         // If no resample frequency is specified, default to requested value
  60         if ( output_rate == 0 )
  61                 output_rate = *frequency;
  62
  63         // Restore the original get_audio
  64         frame->get_audio = mlt_frame_pop_audio( frame );
  65
  66         // Get the producer's audio
  67         mlt_frame_get_audio( frame, buffer, format, frequency, &channels_avail, samples );
  68
  69         // Duplicate channels as necessary
  70         if ( channels_avail < *channels )
  71         {
  72                 int size = *channels * *samples * sizeof( int16_t );
  73                 int16_t *new_buffer = mlt_pool_alloc( size );
  74                 int j, k = 0;
  75
  76                 // Duplicate the existing channels
  77                 for ( i = 0; i < *samples; i++ )
  78                 {
  79                         for ( j = 0; j < *channels; j++ )
  80                         {
  81                                 new_buffer[ ( i * *channels ) + j ] = (*buffer)[ ( i * channels_avail ) + k ];
  82                                 k = ( k + 1 ) % channels_avail;
  83                         }
  84                 }
  85
  86                 // Update the audio buffer now - destroys the old
  87                 mlt_properties_set_data( properties, "audio", new_buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
  88
  89                 *buffer = new_buffer;
  90         }
  91         else if ( channels_avail == 6 && *channels == 2 )
  92         {
  93                 // Nasty hack for ac3 5.1 audio - may be a cause of failure?
  94                 int size = *channels * *samples * sizeof( int16_t );
  95                 int16_t *new_buffer = mlt_pool_alloc( size );
  96
  97                 // Drop all but the first *channels
  98                 for ( i = 0; i < *samples; i++ )
  99                 {
 100                         new_buffer[ ( i * *channels ) + 0 ] = (*buffer)[ ( i * channels_avail ) + 2 ];
 101                         new_buffer[ ( i * *channels ) + 1 ] = (*buffer)[ ( i * channels_avail ) + 3 ];
 102                 }
 103
 104                 // Update the audio buffer now - destroys the old
 105                 mlt_properties_set_data( properties, "audio", new_buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
 106
 107                 *buffer = new_buffer;
 108         }
 109
 110         // Return now if no work to do
 111         if ( output_rate != *frequency )
 112         {
 113                 // Will store number of samples created
 114                 int used = 0;
 115
 116                 // Create a resampler if nececessary
 117                 if ( resample == NULL || *frequency != mlt_properties_get_int( filter_properties, "last_frequency" ) )
 118                 {
 119                         // Create the resampler
 120                         resample = audio_resample_init( *channels, *channels, output_rate, *frequency );
 121
 122                         // And store it on properties
 123                         mlt_properties_set_data( filter_properties, "audio_resample", resample, 0, ( mlt_destructor )audio_resample_close, NULL );
 124
 125                         // And remember what it was created for
 126                         mlt_properties_set_int( filter_properties, "last_frequency", *frequency );
 127                 }
 128
 129                 // Resample the audio
 130                 used = audio_resample( resample, sample_buffer, *buffer, *samples );
 131
 132                 // Resize if necessary
 133                 if ( used > *samples )
 134                 {
 135                         *buffer = mlt_pool_realloc( *buffer, *samples * *channels * sizeof( int16_t ) );
 136                         mlt_properties_set_data( properties, "audio", *buffer, *channels * used * sizeof( int16_t ), mlt_pool_release, NULL );
 137                 }
 138
 139                 // Copy samples
 140                 memcpy( *buffer, sample_buffer, *channels * used * sizeof( int16_t ) );
 141
 142                 // Update output variables
 143                 *samples = used;
 144                 *frequency = output_rate;
 145         }
 146
 147         return 0;
 148 }
 149
 150 /** Filter processing.
 151 */
 152
 153 static mlt_frame filter_process( mlt_filter this, mlt_frame frame )
 154 {
 155         // Only call this if we have a means to get audio
 156         if ( frame->get_audio != NULL )
 157         {
 158                 // Push the original method on to the stack
 159                 mlt_frame_push_audio( frame, frame->get_audio );
 160
 161                 // Push the filter on to the stack
 162                 mlt_frame_push_audio( frame, this );
 163
 164                 // Assign our get_audio method
 165                 frame->get_audio = resample_get_audio;
 166         }
 167
 168         return frame;
 169 }
 170
 171 /** Constructor for the filter.
 172 */
 173
 174 mlt_filter filter_avresample_init( char *arg )
 175 {
 176         // Create a filter
 177         mlt_filter this = mlt_filter_new( );
 178
 179         // Initialise if successful
 180         if ( this != NULL )
 181         {
 182                 // Calculate size of the buffer
 183                 int size = AVCODEC_MAX_AUDIO_FRAME_SIZE * sizeof( int16_t );
 184
 185                 // Allocate the buffer
 186                 int16_t *buffer = mlt_pool_alloc( size );
 187
 188                 // Assign the process method
 189                 this->process = filter_process;
 190
 191                 // Deal with argument
 192                 if ( arg != NULL )
 193                         mlt_properties_set( mlt_filter_properties( this ), "frequency", arg );
 194
 195                 // Default to 2 channel output
 196                 mlt_properties_set_int( mlt_filter_properties( this ), "channels", 2 );
 197
 198                 // Store the buffer
 199                 mlt_properties_set_data( mlt_filter_properties( this ), "buffer", buffer, size, mlt_pool_release, NULL );
 200         }
 201
 202         return this;
 203 }