git.sesse.net Git - vlc/blob - modules/codec/avcodec/audio.c

   1 /*****************************************************************************
   2  * audio.c: audio decoder using libavcodec library
   3  *****************************************************************************
   4  * Copyright (C) 1999-2003 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Laurent Aimar <fenrir@via.ecp.fr>
   8  *          Gildas Bazin <gbazin@videolan.org>
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU Lesser General Public License as published by
  12  * the Free Software Foundation; either version 2.1 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  18  * GNU Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public License
  21  * along with this program; if not, write to the Free Software Foundation,
  22  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  23  *****************************************************************************/
  24
  25 /*****************************************************************************
  26  * Preamble
  27  *****************************************************************************/
  28 #ifdef HAVE_CONFIG_H
  29 # include "config.h"
  30 #endif
  31
  32 #include <assert.h>
  33
  34 #include <vlc_common.h>
  35 #include <vlc_aout.h>
  36 #include <vlc_codec.h>
  37 #include <vlc_avcodec.h>
  38
  39 #include <libavcodec/avcodec.h>
  40 #include <libavutil/mem.h>
  41
  42 #include <libavutil/audioconvert.h>
  43
  44 #include "avcodec.h"
  45
  46 /*****************************************************************************
  47  * decoder_sys_t : decoder descriptor
  48  *****************************************************************************/
  49 struct decoder_sys_t
  50 {
  51     AVCODEC_COMMON_MEMBERS
  52
  53     /*
  54      * Output properties
  55      */
  56     audio_sample_format_t aout_format;
  57     date_t                end_date;
  58
  59     /* */
  60     int     i_reject_count;
  61
  62     /* */
  63     bool    b_extract;
  64     int     pi_extraction[AOUT_CHAN_MAX];
  65     int     i_previous_channels;
  66     uint64_t i_previous_layout;
  67 };
  68
  69 #define BLOCK_FLAG_PRIVATE_REALLOCATED (1 << BLOCK_FLAG_PRIVATE_SHIFT)
  70
  71 static void SetupOutputFormat( decoder_t *p_dec, bool b_trust );
  72 static block_t *DecodeAudio( decoder_t *, block_t ** );
  73
  74 static void InitDecoderConfig( decoder_t *p_dec, AVCodecContext *p_context )
  75 {
  76     if( p_dec->fmt_in.i_extra > 0 )
  77     {
  78         const uint8_t * const p_src = p_dec->fmt_in.p_extra;
  79
  80         int i_offset = 0;
  81         int i_size = p_dec->fmt_in.i_extra;
  82
  83         if( p_dec->fmt_in.i_codec == VLC_CODEC_ALAC )
  84         {
  85             static const uint8_t p_pattern[] = { 0, 0, 0, 36, 'a', 'l', 'a', 'c' };
  86             /* Find alac atom XXX it is a bit ugly */
  87             for( i_offset = 0; i_offset < i_size - (int)sizeof(p_pattern); i_offset++ )
  88             {
  89                 if( !memcmp( &p_src[i_offset], p_pattern, sizeof(p_pattern) ) )
  90                     break;
  91             }
  92             i_size = __MIN( p_dec->fmt_in.i_extra - i_offset, 36 );
  93             if( i_size < 36 )
  94                 i_size = 0;
  95         }
  96
  97         if( i_size > 0 )
  98         {
  99             p_context->extradata =
 100                 av_malloc( i_size + FF_INPUT_BUFFER_PADDING_SIZE );
 101             if( p_context->extradata )
 102             {
 103                 uint8_t *p_dst = p_context->extradata;
 104
 105                 p_context->extradata_size = i_size;
 106
 107                 memcpy( &p_dst[0],            &p_src[i_offset], i_size );
 108                 memset( &p_dst[i_size], 0, FF_INPUT_BUFFER_PADDING_SIZE );
 109             }
 110         }
 111     }
 112     else
 113     {
 114         p_context->extradata_size = 0;
 115         p_context->extradata = NULL;
 116     }
 117 }
 118
 119 static int OpenAudioCodec( decoder_t *p_dec )
 120 {
 121     decoder_sys_t *p_sys = p_dec->p_sys;
 122
 123     if( p_sys->p_context->extradata_size <= 0 )
 124     {
 125         if( p_sys->p_codec->id == AV_CODEC_ID_VORBIS ||
 126             ( p_sys->p_codec->id == AV_CODEC_ID_AAC &&
 127               !p_dec->fmt_in.b_packetized ) )
 128         {
 129             msg_Warn( p_dec, "waiting for extra data for codec %s",
 130                       p_sys->p_codec->name );
 131             return 1;
 132         }
 133     }
 134
 135     p_sys->p_context->sample_rate = p_dec->fmt_in.audio.i_rate;
 136     p_sys->p_context->channels = p_dec->fmt_in.audio.i_channels;
 137     p_sys->p_context->block_align = p_dec->fmt_in.audio.i_blockalign;
 138     p_sys->p_context->bit_rate = p_dec->fmt_in.i_bitrate;
 139     p_sys->p_context->bits_per_coded_sample =
 140                                            p_dec->fmt_in.audio.i_bitspersample;
 141
 142     if( p_sys->p_codec->id == AV_CODEC_ID_ADPCM_G726 &&
 143         p_sys->p_context->bit_rate > 0 &&
 144         p_sys->p_context->sample_rate >  0)
 145         p_sys->p_context->bits_per_coded_sample = p_sys->p_context->bit_rate
 146                                                / p_sys->p_context->sample_rate;
 147
 148     return ffmpeg_OpenCodec( p_dec );
 149 }
 150
 151 /**
 152  * Allocates decoded audio buffer for libavcodec to use.
 153  */
 154 #if (LIBAVCODEC_VERSION_MAJOR >= 55)
 155 typedef struct
 156 {
 157     block_t self;
 158     AVFrame *frame;
 159 } vlc_av_frame_t;
 160
 161 static void vlc_av_frame_Release(block_t *block)
 162 {
 163     vlc_av_frame_t *b = (void *)block;
 164
 165     av_frame_free(&b->frame);
 166     free(b);
 167 }
 168
 169 static block_t *vlc_av_frame_Wrap(AVFrame *frame)
 170 {
 171     for (unsigned i = 1; i < AV_NUM_DATA_POINTERS; i++)
 172         assert(frame->linesize[i] == 0); /* only packed frame supported */
 173
 174     if (av_frame_make_writable(frame)) /* TODO: read-only block_t */
 175         return NULL;
 176
 177     vlc_av_frame_t *b = malloc(sizeof (*b));
 178     if (unlikely(b == NULL))
 179         return NULL;
 180
 181     block_t *block = &b->self;
 182
 183     block_Init(block, frame->extended_data[0], frame->linesize[0]);
 184     block->i_nb_samples = frame->nb_samples;
 185     block->pf_release = vlc_av_frame_Release;
 186     b->frame = frame;
 187     return block;
 188 }
 189 #else
 190 static int GetAudioBuf( AVCodecContext *ctx, AVFrame *buf )
 191 {
 192     block_t *block;
 193     bool planar = av_sample_fmt_is_planar( ctx->sample_fmt );
 194     unsigned channels = planar ? 1 : ctx->channels;
 195     unsigned planes = planar ? ctx->channels : 1;
 196
 197     int bytes = av_samples_get_buffer_size( &buf->linesize[0], channels,
 198                                             buf->nb_samples, ctx->sample_fmt,
 199                                             16 );
 200     assert( bytes >= 0 );
 201     block = block_Alloc( bytes * planes );
 202     if( unlikely(block == NULL) )
 203         return AVERROR(ENOMEM);
 204
 205     block->i_nb_samples = buf->nb_samples;
 206     buf->opaque = block;
 207
 208     if( planes > AV_NUM_DATA_POINTERS )
 209     {
 210         uint8_t **ext = malloc( sizeof( *ext ) * planes );
 211         if( unlikely(ext == NULL) )
 212         {
 213             block_Release( block );
 214             return AVERROR(ENOMEM);
 215         }
 216         buf->extended_data = ext;
 217     }
 218     else
 219         buf->extended_data = buf->data;
 220
 221     uint8_t *buffer = block->p_buffer;
 222     for( unsigned i = 0; i < planes; i++ )
 223     {
 224         buf->linesize[i] = buf->linesize[0];
 225         buf->extended_data[i] = buffer;
 226         buffer += bytes;
 227     }
 228
 229     return 0;
 230 }
 231 #endif
 232
 233 /*****************************************************************************
 234  * InitAudioDec: initialize audio decoder
 235  *****************************************************************************
 236  * The avcodec codec will be opened, some memory allocated.
 237  *****************************************************************************/
 238 int InitAudioDec( decoder_t *p_dec, AVCodecContext *p_context,
 239                   const AVCodec *p_codec )
 240 {
 241     decoder_sys_t *p_sys;
 242
 243     /* Allocate the memory needed to store the decoder's structure */
 244     if( ( p_dec->p_sys = p_sys = malloc(sizeof(*p_sys)) ) == NULL )
 245     {
 246         return VLC_ENOMEM;
 247     }
 248
 249 #if (LIBAVCODEC_VERSION_MAJOR >= 55)
 250     p_context->refcounted_frames = true;
 251 #else
 252     p_context->get_buffer = GetAudioBuf;
 253 #endif
 254     p_sys->p_context = p_context;
 255     p_sys->p_codec = p_codec;
 256     p_sys->b_delayed_open = true;
 257
 258     // Initialize decoder extradata
 259     InitDecoderConfig( p_dec, p_context);
 260
 261     /* ***** Open the codec ***** */
 262     if( OpenAudioCodec( p_dec ) < 0 )
 263     {
 264         av_free( p_context->extradata );
 265         free( p_sys );
 266         return VLC_EGENERIC;
 267     }
 268
 269     p_sys->i_reject_count = 0;
 270     p_sys->b_extract = false;
 271     p_sys->i_previous_channels = 0;
 272     p_sys->i_previous_layout = 0;
 273
 274     /* */
 275     p_dec->fmt_out.i_cat = AUDIO_ES;
 276     /* Try to set as much information as possible but do not trust it */
 277     SetupOutputFormat( p_dec, false );
 278
 279     date_Set( &p_sys->end_date, 0 );
 280     if( p_dec->fmt_out.audio.i_rate )
 281         date_Init( &p_sys->end_date, p_dec->fmt_out.audio.i_rate, 1 );
 282     else if( p_dec->fmt_in.audio.i_rate )
 283         date_Init( &p_sys->end_date, p_dec->fmt_in.audio.i_rate, 1 );
 284
 285     p_dec->pf_decode_audio = DecodeAudio;
 286     return VLC_SUCCESS;
 287 }
 288
 289 /*****************************************************************************
 290  * DecodeAudio: Called to decode one frame
 291  *****************************************************************************/
 292 static block_t *DecodeAudio( decoder_t *p_dec, block_t **pp_block )
 293 {
 294     decoder_sys_t *p_sys = p_dec->p_sys;
 295     AVCodecContext *ctx = p_sys->p_context;
 296
 297     if( !pp_block || !*pp_block )
 298         return NULL;
 299
 300     block_t *p_block = *pp_block;
 301
 302     if( !ctx->extradata_size && p_dec->fmt_in.i_extra && p_sys->b_delayed_open)
 303     {
 304         InitDecoderConfig( p_dec, ctx );
 305         OpenAudioCodec( p_dec );
 306     }
 307
 308     if( p_sys->b_delayed_open )
 309         goto end;
 310
 311     if( p_block->i_flags & (BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
 312     {
 313         avcodec_flush_buffers( ctx );
 314         date_Set( &p_sys->end_date, 0 );
 315
 316         if( ctx->codec_id == AV_CODEC_ID_MP2 ||
 317             ctx->codec_id == AV_CODEC_ID_MP3 )
 318             p_sys->i_reject_count = 3;
 319
 320         goto end;
 321     }
 322
 323     /* We've just started the stream, wait for the first PTS. */
 324     if( !date_Get( &p_sys->end_date ) && p_block->i_pts <= VLC_TS_INVALID )
 325         goto end;
 326
 327     if( p_block->i_buffer <= 0 )
 328         goto end;
 329
 330     if( (p_block->i_flags & BLOCK_FLAG_PRIVATE_REALLOCATED) == 0 )
 331     {
 332         p_block = block_Realloc( p_block, 0, p_block->i_buffer + FF_INPUT_BUFFER_PADDING_SIZE );
 333         if( !p_block )
 334             return NULL;
 335         *pp_block = p_block;
 336         p_block->i_buffer -= FF_INPUT_BUFFER_PADDING_SIZE;
 337         memset( &p_block->p_buffer[p_block->i_buffer], 0, FF_INPUT_BUFFER_PADDING_SIZE );
 338
 339         p_block->i_flags |= BLOCK_FLAG_PRIVATE_REALLOCATED;
 340     }
 341
 342 #if (LIBAVCODEC_VERSION_MAJOR >= 55)
 343     AVFrame *frame = av_frame_alloc();
 344     if (unlikely(frame == NULL))
 345         goto end;
 346 #else
 347     AVFrame *frame = &(AVFrame) { };
 348 #endif
 349
 350     for( int got_frame = 0; !got_frame; )
 351     {
 352         if( p_block->i_buffer == 0 )
 353             goto end;
 354
 355         AVPacket pkt;
 356         av_init_packet( &pkt );
 357         pkt.data = p_block->p_buffer;
 358         pkt.size = p_block->i_buffer;
 359
 360         int used = avcodec_decode_audio4( ctx, frame, &got_frame, &pkt );
 361         if( used < 0 )
 362         {
 363             msg_Warn( p_dec, "cannot decode one frame (%zu bytes)",
 364                       p_block->i_buffer );
 365             goto end;
 366         }
 367
 368         assert( p_block->i_buffer >= (unsigned)used );
 369         p_block->p_buffer += used;
 370         p_block->i_buffer -= used;
 371     }
 372
 373     if( ctx->channels <= 0 || ctx->channels > 8 || ctx->sample_rate <= 0 )
 374     {
 375         msg_Warn( p_dec, "invalid audio properties channels count %d, sample rate %d",
 376                   ctx->channels, ctx->sample_rate );
 377         goto end;
 378     }
 379
 380     if( p_dec->fmt_out.audio.i_rate != (unsigned int)ctx->sample_rate )
 381         date_Init( &p_sys->end_date, ctx->sample_rate, 1 );
 382
 383     if( p_block->i_pts > VLC_TS_INVALID &&
 384         p_block->i_pts > date_Get( &p_sys->end_date ) )
 385     {
 386         date_Set( &p_sys->end_date, p_block->i_pts );
 387     }
 388
 389     if( p_block->i_buffer == 0 )
 390     {   /* Done with this buffer */
 391         block_Release( p_block );
 392         p_block = NULL;
 393         *pp_block = NULL;
 394     }
 395
 396 #if (LIBAVCODEC_VERSION_MAJOR < 55)
 397     /* NOTE WELL: Beyond this point, p_block refers to the DECODED block! */
 398     p_block = frame->opaque;
 399 #endif
 400     SetupOutputFormat( p_dec, true );
 401     if( decoder_UpdateAudioFormat( p_dec ) )
 402         goto drop;
 403
 404     /* Interleave audio if required */
 405     if( av_sample_fmt_is_planar( ctx->sample_fmt ) )
 406 #if (LIBAVCODEC_VERSION_MAJOR >= 55)
 407     {
 408         p_block = block_Alloc(frame->linesize[0] * ctx->channels);
 409         if (unlikely(p_block == NULL))
 410             goto drop;
 411
 412         const void *planes[ctx->channels];
 413         for (int i = 0; i < ctx->channels; i++)
 414             planes[i] = frame->extended_data[i];
 415
 416         aout_Interleave(p_block->p_buffer, planes, frame->nb_samples,
 417                         ctx->channels, p_dec->fmt_out.audio.i_format);
 418         p_block->i_nb_samples = frame->nb_samples;
 419         av_frame_free(&frame);
 420     }
 421     else
 422     {
 423         p_block = vlc_av_frame_Wrap(frame);
 424         if (unlikely(p_block == NULL))
 425             goto drop;
 426     }
 427 #else
 428     {
 429         block_t *p_buffer = block_Alloc( p_block->i_buffer );
 430         if( unlikely(p_buffer == NULL) )
 431             goto drop;
 432
 433         const void *planes[ctx->channels];
 434         for( int i = 0; i < ctx->channels; i++)
 435             planes[i] = frame->extended_data[i];
 436
 437         aout_Interleave( p_buffer->p_buffer, planes, frame->nb_samples,
 438                          ctx->channels, p_dec->fmt_out.audio.i_format );
 439         if( ctx->channels > AV_NUM_DATA_POINTERS )
 440             free( frame->extended_data );
 441         block_Release( p_block );
 442         p_block = p_buffer;
 443     }
 444     p_block->i_nb_samples = frame->nb_samples;
 445 #endif
 446
 447     if (p_sys->b_extract)
 448     {   /* TODO: do not drop channels... at least not here */
 449         block_t *p_buffer = block_Alloc( p_dec->fmt_out.audio.i_bytes_per_frame
 450                                          * p_block->i_nb_samples );
 451         if( unlikely(p_buffer == NULL) )
 452             goto drop;
 453         aout_ChannelExtract( p_buffer->p_buffer,
 454                              p_dec->fmt_out.audio.i_channels,
 455                              p_block->p_buffer, ctx->channels,
 456                              p_block->i_nb_samples, p_sys->pi_extraction,
 457                              p_dec->fmt_out.audio.i_bitspersample );
 458         p_buffer->i_nb_samples = p_block->i_nb_samples;
 459         block_Release( p_block );
 460         p_block = p_buffer;
 461     }
 462
 463     /* Silent unwanted samples */
 464     if( p_sys->i_reject_count > 0 )
 465     {
 466         memset( p_block->p_buffer, 0, p_block->i_buffer );
 467         p_sys->i_reject_count--;
 468     }
 469
 470     p_block->i_buffer = p_block->i_nb_samples
 471                         * p_dec->fmt_out.audio.i_bytes_per_frame;
 472     p_block->i_pts = date_Get( &p_sys->end_date );
 473     p_block->i_length = date_Increment( &p_sys->end_date,
 474                                       p_block->i_nb_samples ) - p_block->i_pts;
 475     return p_block;
 476
 477 end:
 478     *pp_block = NULL;
 479 drop:
 480     if( p_block != NULL )
 481         block_Release(p_block);
 482     return NULL;
 483 }
 484
 485 /*****************************************************************************
 486  *
 487  *****************************************************************************/
 488
 489 vlc_fourcc_t GetVlcAudioFormat( int fmt )
 490 {
 491     static const vlc_fourcc_t fcc[] = {
 492         [AV_SAMPLE_FMT_U8]    = VLC_CODEC_U8,
 493         [AV_SAMPLE_FMT_S16]   = VLC_CODEC_S16N,
 494         [AV_SAMPLE_FMT_S32]   = VLC_CODEC_S32N,
 495         [AV_SAMPLE_FMT_FLT]   = VLC_CODEC_FL32,
 496         [AV_SAMPLE_FMT_DBL]   = VLC_CODEC_FL64,
 497         [AV_SAMPLE_FMT_U8P]   = VLC_CODEC_U8,
 498         [AV_SAMPLE_FMT_S16P]  = VLC_CODEC_S16N,
 499         [AV_SAMPLE_FMT_S32P]  = VLC_CODEC_S32N,
 500         [AV_SAMPLE_FMT_FLTP]  = VLC_CODEC_FL32,
 501         [AV_SAMPLE_FMT_DBLP]  = VLC_CODEC_FL64,
 502     };
 503     if( (sizeof(fcc) / sizeof(fcc[0])) > (unsigned)fmt )
 504         return fcc[fmt];
 505     return VLC_CODEC_S16N;
 506 }
 507
 508 static const uint64_t pi_channels_map[][2] =
 509 {
 510     { AV_CH_FRONT_LEFT,        AOUT_CHAN_LEFT },
 511     { AV_CH_FRONT_RIGHT,       AOUT_CHAN_RIGHT },
 512     { AV_CH_FRONT_CENTER,      AOUT_CHAN_CENTER },
 513     { AV_CH_LOW_FREQUENCY,     AOUT_CHAN_LFE },
 514     { AV_CH_BACK_LEFT,         AOUT_CHAN_REARLEFT },
 515     { AV_CH_BACK_RIGHT,        AOUT_CHAN_REARRIGHT },
 516     { AV_CH_FRONT_LEFT_OF_CENTER, 0 },
 517     { AV_CH_FRONT_RIGHT_OF_CENTER, 0 },
 518     { AV_CH_BACK_CENTER,       AOUT_CHAN_REARCENTER },
 519     { AV_CH_SIDE_LEFT,         AOUT_CHAN_MIDDLELEFT },
 520     { AV_CH_SIDE_RIGHT,        AOUT_CHAN_MIDDLERIGHT },
 521     { AV_CH_TOP_CENTER,        0 },
 522     { AV_CH_TOP_FRONT_LEFT,    0 },
 523     { AV_CH_TOP_FRONT_CENTER,  0 },
 524     { AV_CH_TOP_FRONT_RIGHT,   0 },
 525     { AV_CH_TOP_BACK_LEFT,     0 },
 526     { AV_CH_TOP_BACK_CENTER,   0 },
 527     { AV_CH_TOP_BACK_RIGHT,    0 },
 528     { AV_CH_STEREO_LEFT,       0 },
 529     { AV_CH_STEREO_RIGHT,      0 },
 530 };
 531
 532 static void SetupOutputFormat( decoder_t *p_dec, bool b_trust )
 533 {
 534     decoder_sys_t *p_sys = p_dec->p_sys;
 535
 536     p_dec->fmt_out.i_codec = GetVlcAudioFormat( p_sys->p_context->sample_fmt );
 537     p_dec->fmt_out.audio.i_format = p_dec->fmt_out.i_codec;
 538     p_dec->fmt_out.audio.i_rate = p_sys->p_context->sample_rate;
 539
 540     /* */
 541     if( p_sys->i_previous_channels == p_sys->p_context->channels &&
 542         p_sys->i_previous_layout == p_sys->p_context->channel_layout )
 543         return;
 544     if( b_trust )
 545     {
 546         p_sys->i_previous_channels = p_sys->p_context->channels;
 547         p_sys->i_previous_layout = p_sys->p_context->channel_layout;
 548     }
 549
 550     /* Specified order
 551      * FIXME should we use fmt_in.audio.i_physical_channels or not ?
 552      */
 553     const unsigned i_order_max = 8 * sizeof(p_sys->p_context->channel_layout);
 554     uint32_t pi_order_src[i_order_max];
 555     int i_channels_src = 0;
 556
 557     if( p_sys->p_context->channel_layout )
 558     {
 559         for( unsigned i = 0; i < sizeof(pi_channels_map)/sizeof(*pi_channels_map); i++ )
 560         {
 561             if( p_sys->p_context->channel_layout & pi_channels_map[i][0] )
 562                 pi_order_src[i_channels_src++] = pi_channels_map[i][1];
 563         }
 564     }
 565     else
 566     {
 567         /* Create default order  */
 568         if( b_trust )
 569             msg_Warn( p_dec, "Physical channel configuration not set : guessing" );
 570         for( unsigned int i = 0; i < __MIN( i_order_max, (unsigned)p_sys->p_context->channels ); i++ )
 571         {
 572             if( i < sizeof(pi_channels_map)/sizeof(*pi_channels_map) )
 573                 pi_order_src[i_channels_src++] = pi_channels_map[i][1];
 574         }
 575     }
 576     if( i_channels_src != p_sys->p_context->channels && b_trust )
 577         msg_Err( p_dec, "Channel layout not understood" );
 578
 579     uint32_t i_layout_dst;
 580     int      i_channels_dst;
 581     p_sys->b_extract = aout_CheckChannelExtraction( p_sys->pi_extraction,
 582                                                     &i_layout_dst, &i_channels_dst,
 583                                                     NULL, pi_order_src, i_channels_src );
 584     if( i_channels_dst != i_channels_src && b_trust )
 585         msg_Warn( p_dec, "%d channels are dropped", i_channels_src - i_channels_dst );
 586
 587     p_dec->fmt_out.audio.i_physical_channels =
 588     p_dec->fmt_out.audio.i_original_channels = i_layout_dst;
 589     aout_FormatPrepare( &p_dec->fmt_out.audio );
 590 }
 591