src/audio_output/common.c

   1 /*****************************************************************************
   2  * common.c : audio output management of common data structures
   3  *****************************************************************************
   4  * Copyright (C) 2002-2007 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Christophe Massiot <massiot@via.ecp.fr>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with this program; if not, write to the Free Software Foundation,
  21  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 #ifdef HAVE_CONFIG_H
  25 # include "config.h"
  26 #endif
  27
  28 #include <limits.h>
  29 #include <assert.h>
  30
  31 #include <vlc_common.h>
  32 #include <vlc_aout.h>
  33 #include "aout_internal.h"
  34
  35 /*
  36  * Formats management (internal and external)
  37  */
  38
  39 /*****************************************************************************
  40  * aout_BitsPerSample : get the number of bits per sample
  41  *****************************************************************************/
  42 unsigned int aout_BitsPerSample( vlc_fourcc_t i_format )
  43 {
  44     switch( vlc_fourcc_GetCodec( AUDIO_ES, i_format ) )
  45     {
  46     case VLC_CODEC_U8:
  47     case VLC_CODEC_S8:
  48     case VLC_CODEC_ALAW:
  49     case VLC_CODEC_MULAW:
  50         return 8;
  51
  52     case VLC_CODEC_U16L:
  53     case VLC_CODEC_S16L:
  54     case VLC_CODEC_U16B:
  55     case VLC_CODEC_S16B:
  56         return 16;
  57
  58     case VLC_CODEC_U24L:
  59     case VLC_CODEC_S24L:
  60     case VLC_CODEC_U24B:
  61     case VLC_CODEC_S24B:
  62         return 24;
  63
  64     case VLC_CODEC_S24L32:
  65     case VLC_CODEC_S24B32:
  66     case VLC_CODEC_U32L:
  67     case VLC_CODEC_U32B:
  68     case VLC_CODEC_S32L:
  69     case VLC_CODEC_S32B:
  70     case VLC_CODEC_F32L:
  71     case VLC_CODEC_F32B:
  72         return 32;
  73
  74     case VLC_CODEC_F64L:
  75     case VLC_CODEC_F64B:
  76         return 64;
  77
  78     default:
  79         /* For these formats the caller has to indicate the parameters
  80          * by hand. */
  81         return 0;
  82     }
  83 }
  84
  85 /*****************************************************************************
  86  * aout_FormatPrepare : compute the number of bytes per frame & frame length
  87  *****************************************************************************/
  88 void aout_FormatPrepare( audio_sample_format_t * p_format )
  89 {
  90
  91     unsigned i_channels = aout_FormatNbChannels( p_format );
  92     if( i_channels > 0 )
  93         p_format->i_channels = i_channels;
  94     p_format->i_bitspersample = aout_BitsPerSample( p_format->i_format );
  95     if( p_format->i_bitspersample > 0 )
  96     {
  97         p_format->i_bytes_per_frame = ( p_format->i_bitspersample / 8 )
  98                                     * p_format->i_channels;
  99         p_format->i_frame_length = 1;
 100     }
 101 }
 102
 103 /*****************************************************************************
 104  * aout_FormatPrintChannels : print a channel in a human-readable form
 105  *****************************************************************************/
 106 const char * aout_FormatPrintChannels( const audio_sample_format_t * p_format )
 107 {
 108     if (p_format->channel_type == AUDIO_CHANNEL_TYPE_AMBISONICS)
 109         return "Ambisonics";
 110
 111     /* AUDIO_CHANNEL_TYPE_BITMAP */
 112     switch ( p_format->i_physical_channels )
 113     {
 114     case AOUT_CHAN_LEFT:
 115     case AOUT_CHAN_RIGHT:
 116     case AOUT_CHAN_CENTER:
 117         if ( (p_format->i_physical_channels & AOUT_CHAN_CENTER)
 118               || (p_format->i_physical_channels
 119                    & (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT)) )
 120             return "Mono";
 121         else if ( p_format->i_physical_channels & AOUT_CHAN_LEFT )
 122             return "Left";
 123         return "Right";
 124     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT:
 125         if ( p_format->i_chan_mode & AOUT_CHANMODE_DOLBYSTEREO )
 126             return "Dolby";
 127         else if ( p_format->i_chan_mode & AOUT_CHANMODE_DUALMONO )
 128             return "Dual-mono";
 129         else if ( p_format->i_physical_channels == AOUT_CHAN_CENTER )
 130             return "Stereo/Mono";
 131         else if ( !(p_format->i_physical_channels & AOUT_CHAN_RIGHT) )
 132             return "Stereo/Left";
 133         else if ( !(p_format->i_physical_channels & AOUT_CHAN_LEFT) )
 134             return "Stereo/Right";
 135         return "Stereo";
 136     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER:
 137         return "3F";
 138     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_REARCENTER:
 139         return "2F1R";
 140     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 141           | AOUT_CHAN_REARCENTER:
 142         return "3F1R";
 143     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 144           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT:
 145         return "2F2R";
 146     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 147           | AOUT_CHAN_MIDDLELEFT | AOUT_CHAN_MIDDLERIGHT:
 148         return "2F2M";
 149     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 150           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT:
 151         return "3F2R";
 152     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 153           | AOUT_CHAN_MIDDLELEFT | AOUT_CHAN_MIDDLERIGHT:
 154         return "3F2M";
 155
 156     case AOUT_CHAN_CENTER | AOUT_CHAN_LFE:
 157         if ( (p_format->i_physical_channels & AOUT_CHAN_CENTER)
 158               || (p_format->i_physical_channels
 159                    & (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT)) )
 160             return "Mono/LFE";
 161         else if ( p_format->i_physical_channels & AOUT_CHAN_LEFT )
 162             return "Left/LFE";
 163         return "Right/LFE";
 164     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_LFE:
 165         if ( p_format->i_chan_mode & AOUT_CHANMODE_DOLBYSTEREO )
 166             return "Dolby/LFE";
 167         else if ( p_format->i_chan_mode & AOUT_CHANMODE_DUALMONO )
 168             return "Dual-mono/LFE";
 169         else if ( p_format->i_physical_channels == AOUT_CHAN_CENTER )
 170             return "Mono/LFE";
 171         else if ( !(p_format->i_physical_channels & AOUT_CHAN_RIGHT) )
 172             return "Stereo/Left/LFE";
 173         else if ( !(p_format->i_physical_channels & AOUT_CHAN_LEFT) )
 174             return "Stereo/Right/LFE";
 175          return "Stereo/LFE";
 176     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER | AOUT_CHAN_LFE:
 177         return "3F/LFE";
 178     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_REARCENTER
 179           | AOUT_CHAN_LFE:
 180         return "2F1R/LFE";
 181     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 182           | AOUT_CHAN_REARCENTER | AOUT_CHAN_LFE:
 183         return "3F1R/LFE";
 184     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 185           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_LFE:
 186         return "2F2R/LFE";
 187     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 188           | AOUT_CHAN_MIDDLELEFT | AOUT_CHAN_MIDDLERIGHT | AOUT_CHAN_LFE:
 189         return "2F2M/LFE";
 190     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 191           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_LFE:
 192         return "3F2R/LFE";
 193     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 194           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_REARCENTER
 195           | AOUT_CHAN_LFE:
 196         return "3F3R/LFE";
 197     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 198           | AOUT_CHAN_MIDDLELEFT | AOUT_CHAN_MIDDLERIGHT | AOUT_CHAN_LFE:
 199         return "3F2M/LFE";
 200     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 201           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_MIDDLELEFT
 202           | AOUT_CHAN_MIDDLERIGHT:
 203         return "3F2M2R";
 204     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 205           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_MIDDLELEFT
 206           | AOUT_CHAN_MIDDLERIGHT | AOUT_CHAN_LFE:
 207         return "3F2M2R/LFE";
 208     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 209           | AOUT_CHAN_REARCENTER | AOUT_CHAN_MIDDLELEFT
 210           | AOUT_CHAN_MIDDLERIGHT | AOUT_CHAN_LFE:
 211         return "3F2M1R/LFE";
 212     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 213           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_REARCENTER
 214           | AOUT_CHAN_MIDDLELEFT | AOUT_CHAN_MIDDLERIGHT | AOUT_CHAN_LFE:
 215         return "3F2M3R/LFE";
 216     }
 217
 218     return "Unknown-chan-mask";
 219 }
 220
 221 #undef aout_FormatPrint
 222 /**
 223  * Prints an audio sample format in a human-readable form.
 224  */
 225 void aout_FormatPrint( vlc_object_t *obj, const char *psz_text,
 226                        const audio_sample_format_t *p_format )
 227 {
 228     msg_Dbg( obj, "%s '%4.4s' %d Hz %s frame=%d samples/%d bytes", psz_text,
 229              (char *)&p_format->i_format, p_format->i_rate,
 230              aout_FormatPrintChannels( p_format ),
 231              p_format->i_frame_length, p_format->i_bytes_per_frame );
 232 }
 233
 234 #undef aout_FormatsPrint
 235 /**
 236  * Prints two formats in a human-readable form
 237  */
 238 void aout_FormatsPrint( vlc_object_t *obj, const char * psz_text,
 239                         const audio_sample_format_t * p_format1,
 240                         const audio_sample_format_t * p_format2 )
 241 {
 242     msg_Dbg( obj, "%s '%4.4s'->'%4.4s' %d Hz->%d Hz %s->%s",
 243              psz_text,
 244              (char *)&p_format1->i_format, (char *)&p_format2->i_format,
 245              p_format1->i_rate, p_format2->i_rate,
 246              aout_FormatPrintChannels( p_format1 ),
 247              aout_FormatPrintChannels( p_format2 ) );
 248 }
 249
 250 /*****************************************************************************
 251  * aout_CheckChannelReorder : Check if we need to do some channel re-ordering
 252  *****************************************************************************/
 253 unsigned aout_CheckChannelReorder( const uint32_t *chans_in,
 254                                    const uint32_t *chans_out,
 255                                    uint32_t mask, uint8_t *restrict table )
 256 {
 257     static_assert(AOUT_CHAN_MAX <= (sizeof (mask) * CHAR_BIT), "Missing bits");
 258
 259     unsigned channels = 0;
 260
 261     if( chans_in == NULL )
 262         chans_in = pi_vlc_chan_order_wg4;
 263     if( chans_out == NULL )
 264         chans_out = pi_vlc_chan_order_wg4;
 265
 266     for( unsigned i = 0; chans_in[i]; i++ )
 267     {
 268         const uint32_t chan = chans_in[i];
 269         if( !(mask & chan) )
 270             continue;
 271
 272         unsigned index = 0;
 273         for( unsigned j = 0; chan != chans_out[j]; j++ )
 274             if( mask & chans_out[j] )
 275                 index++;
 276
 277         table[channels++] = index;
 278     }
 279
 280     for( unsigned i = 0; i < channels; i++ )
 281         if( table[i] != i )
 282             return channels;
 283     return 0;
 284 }
 285
 286 /**
 287  * Reorders audio samples within a block of linear audio interleaved samples.
 288  * \param ptr start address of the block of samples
 289  * \param bytes size of the block in bytes (must be a multiple of the product
 290  *              of the channels count and the sample size)
 291  * \param channels channels count (also length of the chans_table table)
 292  * \param chans_table permutation table to reorder the channels
 293  *                    (usually computed by aout_CheckChannelReorder())
 294  * \param fourcc sample format (must be a linear sample format)
 295  * \note The samples must be naturally aligned in memory.
 296  */
 297 void aout_ChannelReorder( void *ptr, size_t bytes, uint8_t channels,
 298                           const uint8_t *restrict chans_table, vlc_fourcc_t fourcc )
 299 {
 300     if( unlikely(bytes == 0) )
 301         return;
 302
 303     assert( channels != 0 );
 304
 305     /* The audio formats supported in audio output are inlined. For other
 306      * formats (used in demuxers and muxers), memcpy() is used to avoid
 307      * breaking type punning. */
 308 #define REORDER_TYPE(type) \
 309 do { \
 310     const size_t frames = (bytes / sizeof (type)) / channels; \
 311     type *buf = ptr; \
 312 \
 313     for( size_t i = 0; i < frames; i++ ) \
 314     { \
 315         type tmp[AOUT_CHAN_MAX]; \
 316 \
 317         for( size_t j = 0; j < channels; j++ ) \
 318             tmp[chans_table[j]] = buf[j]; \
 319         memcpy( buf, tmp, sizeof (type) * channels ); \
 320         buf += channels; \
 321     } \
 322 } while(0)
 323
 324     if( likely(channels <= AOUT_CHAN_MAX) )
 325     {
 326         switch( fourcc )
 327         {
 328             case VLC_CODEC_U8:   REORDER_TYPE(uint8_t); return;
 329             case VLC_CODEC_S16N: REORDER_TYPE(int16_t); return;
 330             case VLC_CODEC_FL32: REORDER_TYPE(float);   return;
 331             case VLC_CODEC_S32N: REORDER_TYPE(int32_t); return;
 332             case VLC_CODEC_FL64: REORDER_TYPE(double);  return;
 333         }
 334     }
 335
 336     unsigned size = aout_BitsPerSample( fourcc ) / 8;
 337     assert( size != 0 && size <= 8 );
 338
 339     const size_t frames = bytes / (size * channels);
 340     unsigned char *buf = ptr;
 341
 342     for( size_t i = 0; i < frames; i++ )
 343     {
 344         unsigned char tmp[256 * 8];
 345
 346         for( size_t j = 0; j < channels; j++ )
 347              memcpy( tmp + size * chans_table[j], buf + size * j, size );
 348          memcpy( buf, tmp, size * channels );
 349          buf += size * channels;
 350     }
 351 }
 352
 353 /**
 354  * Interleaves audio samples within a block of samples.
 355  * \param dst destination buffer for interleaved samples
 356  * \param srcv source buffers (one per plane) of uninterleaved samples
 357  * \param samples number of samples (per channel/per plane)
 358  * \param chans channels/planes count
 359  * \param fourcc sample format (must be a linear sample format)
 360  * \note The samples must be naturally aligned in memory.
 361  * \warning Destination and source buffers MUST NOT overlap.
 362  */
 363 void aout_Interleave( void *restrict dst, const void *const *srcv,
 364                       unsigned samples, unsigned chans, vlc_fourcc_t fourcc )
 365 {
 366 #define INTERLEAVE_TYPE(type) \
 367 do { \
 368     type *d = dst; \
 369     for( size_t i = 0; i < chans; i++ ) { \
 370         const type *s = srcv[i]; \
 371         for( size_t j = 0, k = 0; j < samples; j++, k += chans ) \
 372             d[k] = *(s++); \
 373         d++; \
 374     } \
 375 } while(0)
 376
 377     switch( fourcc )
 378     {
 379         case VLC_CODEC_U8:   INTERLEAVE_TYPE(uint8_t);  break;
 380         case VLC_CODEC_S16N: INTERLEAVE_TYPE(uint16_t); break;
 381         case VLC_CODEC_FL32: INTERLEAVE_TYPE(float);    break;
 382         case VLC_CODEC_S32N: INTERLEAVE_TYPE(int32_t);  break;
 383         case VLC_CODEC_FL64: INTERLEAVE_TYPE(double);   break;
 384         default:             vlc_assert_unreachable();
 385     }
 386 #undef INTERLEAVE_TYPE
 387 }
 388
 389 /**
 390  * Deinterleaves audio samples within a block of samples.
 391  * \param dst destination buffer for planar samples
 392  * \param src source buffer with interleaved samples
 393  * \param samples number of samples (per channel/per plane)
 394  * \param chans channels/planes count
 395  * \param fourcc sample format (must be a linear sample format)
 396  * \note The samples must be naturally aligned in memory.
 397  * \warning Destination and source buffers MUST NOT overlap.
 398  */
 399 void aout_Deinterleave( void *restrict dst, const void *restrict src,
 400                       unsigned samples, unsigned chans, vlc_fourcc_t fourcc )
 401 {
 402 #define DEINTERLEAVE_TYPE(type) \
 403 do { \
 404     type *d = dst; \
 405     const type *s = src; \
 406     for( size_t i = 0; i < chans; i++ ) { \
 407         for( size_t j = 0, k = 0; j < samples; j++, k += chans ) \
 408             *(d++) = s[k]; \
 409         s++; \
 410     } \
 411 } while(0)
 412
 413     switch( fourcc )
 414     {
 415         case VLC_CODEC_U8:   DEINTERLEAVE_TYPE(uint8_t);  break;
 416         case VLC_CODEC_S16N: DEINTERLEAVE_TYPE(uint16_t); break;
 417         case VLC_CODEC_FL32: DEINTERLEAVE_TYPE(float);    break;
 418         case VLC_CODEC_S32N: DEINTERLEAVE_TYPE(int32_t);  break;
 419         case VLC_CODEC_FL64: DEINTERLEAVE_TYPE(double);   break;
 420         default:             vlc_assert_unreachable();
 421     }
 422 #undef DEINTERLEAVE_TYPE
 423 }
 424
 425 /*****************************************************************************
 426  * aout_ChannelExtract:
 427  *****************************************************************************/
 428 static inline void ExtractChannel( uint8_t *pi_dst, int i_dst_channels,
 429                                    const uint8_t *pi_src, int i_src_channels,
 430                                    int i_sample_count,
 431                                    const int *pi_selection, int i_bytes )
 432 {
 433     for( int i = 0; i < i_sample_count; i++ )
 434     {
 435         for( int j = 0; j < i_dst_channels; j++ )
 436             memcpy( &pi_dst[j * i_bytes], &pi_src[pi_selection[j] * i_bytes], i_bytes );
 437         pi_dst += i_dst_channels * i_bytes;
 438         pi_src += i_src_channels * i_bytes;
 439     }
 440 }
 441
 442 void aout_ChannelExtract( void *p_dst, int i_dst_channels,
 443                           const void *p_src, int i_src_channels,
 444                           int i_sample_count, const int *pi_selection, int i_bits_per_sample )
 445 {
 446     /* It does not work in place */
 447     assert( p_dst != p_src );
 448
 449     /* Force the compiler to inline for the specific cases so it can optimize */
 450     if( i_bits_per_sample == 8 )
 451         ExtractChannel( p_dst, i_dst_channels, p_src, i_src_channels, i_sample_count, pi_selection, 1 );
 452     else  if( i_bits_per_sample == 16 )
 453         ExtractChannel( p_dst, i_dst_channels, p_src, i_src_channels, i_sample_count, pi_selection, 2 );
 454     else  if( i_bits_per_sample == 32 )
 455         ExtractChannel( p_dst, i_dst_channels, p_src, i_src_channels, i_sample_count, pi_selection, 4 );
 456     else  if( i_bits_per_sample == 64 )
 457         ExtractChannel( p_dst, i_dst_channels, p_src, i_src_channels, i_sample_count, pi_selection, 8 );
 458 }
 459
 460 bool aout_CheckChannelExtraction( int *pi_selection,
 461                                   uint32_t *pi_layout, int *pi_channels,
 462                                   const uint32_t pi_order_dst[AOUT_CHAN_MAX],
 463                                   const uint32_t *pi_order_src, int i_channels )
 464 {
 465     static_assert(AOUT_CHAN_MAX <= (sizeof (*pi_order_dst) * CHAR_BIT),
 466                   "Missing bits");
 467
 468     uint32_t i_layout = 0;
 469     int i_out = 0;
 470     int pi_index[AOUT_CHAN_MAX];
 471
 472     /* */
 473     if( !pi_order_dst )
 474         pi_order_dst = pi_vlc_chan_order_wg4;
 475
 476     /* */
 477     for( int i = 0; i < i_channels; i++ )
 478     {
 479         /* Ignore unknown or duplicated channels or not present in output */
 480         if( !pi_order_src[i] || (i_layout & pi_order_src[i]) )
 481             continue;
 482
 483         for( int j = 0; j < AOUT_CHAN_MAX; j++ )
 484         {
 485             if( pi_order_dst[j] == pi_order_src[i] )
 486             {
 487                 assert( i_out < AOUT_CHAN_MAX );
 488                 pi_index[i_out++] = i;
 489                 i_layout |= pi_order_src[i];
 490                 break;
 491             }
 492         }
 493     }
 494
 495     /* */
 496     for( int i = 0, j = 0; i < AOUT_CHAN_MAX; i++ )
 497     {
 498         for( int k = 0; k < i_out; k++ )
 499         {
 500             if( pi_order_dst[i] == pi_order_src[pi_index[k]] )
 501             {
 502                 pi_selection[j++] = pi_index[k];
 503                 break;
 504             }
 505         }
 506     }
 507
 508     *pi_layout = i_layout;
 509     *pi_channels = i_out;
 510
 511     for( int i = 0; i < i_out; i++ )
 512     {
 513         if( pi_selection[i] != i )
 514             return true;
 515     }
 516     return i_out != i_channels;
 517 }
 518
 519 /* Return the order in which filters should be inserted */
 520 static int FilterOrder( const char *psz_name )
 521 {
 522     static const struct {
 523         const char psz_name[10];
 524         int        i_order;
 525     } filter[] = {
 526         { "equalizer",  0 },
 527     };
 528     for( unsigned i = 0; i < ARRAY_SIZE(filter); i++ )
 529     {
 530         if( !strcmp( filter[i].psz_name, psz_name ) )
 531             return filter[i].i_order;
 532     }
 533     return INT_MAX;
 534 }
 535
 536 /* This function will add or remove a module from a string list (colon
 537  * separated). It will return true if there is a modification
 538  * In case p_aout is NULL, we will use configuration instead of variable */
 539 bool aout_ChangeFilterString( vlc_object_t *p_obj, vlc_object_t *p_aout,
 540                               const char *psz_variable,
 541                               const char *psz_name, bool b_add )
 542 {
 543     if( *psz_name == '\0' )
 544         return false;
 545
 546     char *psz_list;
 547     if( p_aout )
 548     {
 549         psz_list = var_GetString( p_aout, psz_variable );
 550     }
 551     else
 552     {
 553         psz_list = var_InheritString( p_obj, psz_variable );
 554     }
 555
 556     /* Split the string into an array of filters */
 557     int i_count = 1;
 558     for( char *p = psz_list; p && *p; p++ )
 559         i_count += *p == ':';
 560     i_count += b_add;
 561
 562     const char **ppsz_filter = calloc( i_count, sizeof(*ppsz_filter) );
 563     if( !ppsz_filter )
 564     {
 565         free( psz_list );
 566         return false;
 567     }
 568     bool b_present = false;
 569     i_count = 0;
 570     for( char *p = psz_list; p && *p; )
 571     {
 572         char *psz_end = strchr(p, ':');
 573         if( psz_end )
 574             *psz_end++ = '\0';
 575         else
 576             psz_end = p + strlen(p);
 577         if( *p )
 578         {
 579             b_present |= !strcmp( p, psz_name );
 580             ppsz_filter[i_count++] = p;
 581         }
 582         p = psz_end;
 583     }
 584     if( b_present == b_add )
 585     {
 586         free( ppsz_filter );
 587         free( psz_list );
 588         return false;
 589     }
 590
 591     if( b_add )
 592     {
 593         int i_order = FilterOrder( psz_name );
 594         int i;
 595         for( i = 0; i < i_count; i++ )
 596         {
 597             if( FilterOrder( ppsz_filter[i] ) > i_order )
 598                 break;
 599         }
 600         if( i < i_count )
 601             memmove( &ppsz_filter[i+1], &ppsz_filter[i], (i_count - i) * sizeof(*ppsz_filter) );
 602         ppsz_filter[i] = psz_name;
 603         i_count++;
 604     }
 605     else
 606     {
 607         for( int i = 0; i < i_count; i++ )
 608         {
 609             if( !strcmp( ppsz_filter[i], psz_name ) )
 610                 ppsz_filter[i] = "";
 611         }
 612     }
 613     size_t i_length = 0;
 614     for( int i = 0; i < i_count; i++ )
 615         i_length += 1 + strlen( ppsz_filter[i] );
 616
 617     char *psz_new = malloc( i_length + 1 );
 618
 619     if( unlikely( !psz_new ) )
 620     {
 621         free( ppsz_filter );
 622         free( psz_list );
 623         return false;
 624     }
 625
 626     *psz_new = '\0';
 627     for( int i = 0; i < i_count; i++ )
 628     {
 629         if( *ppsz_filter[i] == '\0' )
 630             continue;
 631         if( *psz_new )
 632             strcat( psz_new, ":" );
 633         strcat( psz_new, ppsz_filter[i] );
 634     }
 635     free( ppsz_filter );
 636     free( psz_list );
 637
 638     var_SetString( p_obj, psz_variable, psz_new );
 639     if( p_aout )
 640         var_SetString( p_aout, psz_variable, psz_new );
 641     free( psz_new );
 642
 643     return true;
 644 }