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