modules/codec/opus.c

   1 /*****************************************************************************
   2  * opus.c: opus decoder/encoder module making use of libopus.
   3  *****************************************************************************
   4  * Copyright (C) 2003-2009, 2012 VLC authors and VideoLAN
   5  *
   6  * Authors: Gregory Maxwell <greg@xiph.org>
   7  * Based on speex.c by: Gildas Bazin <gbazin@videolan.org>
   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 /*****************************************************************************
  25  * Preamble
  26  *****************************************************************************/
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <vlc_common.h>
  32 #include <vlc_plugin.h>
  33 #include <vlc_input.h>
  34 #include <vlc_codec.h>
  35 #include <vlc_aout.h>
  36 #include "../demux/xiph.h"
  37
  38 #include <ogg/ogg.h>
  39 #include <opus.h>
  40 #include <opus_multistream.h>
  41
  42 #include "opus_header.h"
  43
  44 #ifndef OPUS_SET_GAIN
  45 #include <math.h>
  46 #endif
  47
  48 /*****************************************************************************
  49  * Module descriptor
  50  *****************************************************************************/
  51 static int  OpenDecoder   ( vlc_object_t * );
  52 static void CloseDecoder  ( vlc_object_t * );
  53 #ifdef ENABLE_SOUT
  54 static int  OpenEncoder   ( vlc_object_t * );
  55 static void CloseEncoder  ( vlc_object_t * );
  56 #endif
  57
  58 vlc_module_begin ()
  59     set_category( CAT_INPUT )
  60     set_subcategory( SUBCAT_INPUT_ACODEC )
  61
  62     set_description( N_("Opus audio decoder") )
  63     set_capability( "audio decoder", 100 )
  64     set_shortname( N_("Opus") )
  65     set_callbacks( OpenDecoder, CloseDecoder )
  66
  67 #ifdef ENABLE_SOUT
  68     add_submodule ()
  69     set_description( N_("Opus audio encoder") )
  70     set_capability( "encoder", 150 )
  71     set_shortname( N_("Opus") )
  72     set_callbacks( OpenEncoder, CloseEncoder )
  73 #endif
  74
  75 vlc_module_end ()
  76
  77 /*****************************************************************************
  78  * decoder_sys_t : opus decoder descriptor
  79  *****************************************************************************/
  80 typedef struct
  81 {
  82     /*
  83      * Input properties
  84      */
  85     bool b_has_headers;
  86
  87     /*
  88      * Opus properties
  89      */
  90     OpusHeader header;
  91     OpusMSDecoder *p_st;
  92
  93     /*
  94      * Common properties
  95      */
  96     date_t end_date;
  97 } decoder_sys_t;
  98
  99 static const int pi_channels_maps[9] =
 100 {
 101     0,
 102     AOUT_CHAN_CENTER,
 103     AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT,
 104     AOUT_CHAN_CENTER | AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT,
 105     AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_REARLEFT
 106      | AOUT_CHAN_REARRIGHT,
 107     AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 108      | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT,
 109     AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 110      | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_LFE,
 111     AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 112      | AOUT_CHAN_REARCENTER | AOUT_CHAN_MIDDLELEFT
 113      | AOUT_CHAN_MIDDLERIGHT | AOUT_CHAN_LFE,
 114     AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER | AOUT_CHAN_REARLEFT
 115      | AOUT_CHAN_REARRIGHT | AOUT_CHAN_MIDDLELEFT | AOUT_CHAN_MIDDLERIGHT
 116      | AOUT_CHAN_LFE,
 117 };
 118
 119 /*
 120 **  channel order as defined in http://www.xiph.org/vorbis/doc/Vorbis_I_spec.html#x1-800004.3.9
 121 */
 122
 123 /* recommended vorbis channel order for 8 channels */
 124 static const uint32_t pi_8channels_in[] =
 125 { AOUT_CHAN_LEFT, AOUT_CHAN_CENTER, AOUT_CHAN_RIGHT,
 126   AOUT_CHAN_MIDDLELEFT, AOUT_CHAN_MIDDLERIGHT,
 127   AOUT_CHAN_REARLEFT, AOUT_CHAN_REARRIGHT,AOUT_CHAN_LFE, 0 };
 128
 129 /* recommended vorbis channel order for 7 channels */
 130 static const uint32_t pi_7channels_in[] =
 131 { AOUT_CHAN_LEFT, AOUT_CHAN_CENTER, AOUT_CHAN_RIGHT,
 132   AOUT_CHAN_MIDDLELEFT, AOUT_CHAN_MIDDLERIGHT,
 133   AOUT_CHAN_REARCENTER, AOUT_CHAN_LFE, 0 };
 134
 135 /* recommended vorbis channel order for 6 channels */
 136 static const uint32_t pi_6channels_in[] =
 137 { AOUT_CHAN_LEFT, AOUT_CHAN_CENTER, AOUT_CHAN_RIGHT,
 138   AOUT_CHAN_REARLEFT, AOUT_CHAN_REARRIGHT, AOUT_CHAN_LFE, 0 };
 139
 140 /* recommended vorbis channel order for 5 channels */
 141 static const uint32_t pi_5channels_in[] =
 142 { AOUT_CHAN_LEFT, AOUT_CHAN_CENTER, AOUT_CHAN_RIGHT,
 143   AOUT_CHAN_REARLEFT, AOUT_CHAN_REARRIGHT, 0 };
 144
 145 /* recommended vorbis channel order for 4 channels */
 146 static const uint32_t pi_4channels_in[] =
 147 { AOUT_CHAN_LEFT, AOUT_CHAN_RIGHT, AOUT_CHAN_REARLEFT, AOUT_CHAN_REARRIGHT, 0 };
 148
 149 /* recommended vorbis channel order for 3 channels */
 150 static const uint32_t pi_3channels_in[] =
 151 { AOUT_CHAN_LEFT, AOUT_CHAN_CENTER, AOUT_CHAN_RIGHT, 0 };
 152
 153 /****************************************************************************
 154  * Local prototypes
 155  ****************************************************************************/
 156
 157 static int  DecodeAudio ( decoder_t *, block_t * );
 158 static void Flush( decoder_t * );
 159 static int  ProcessHeaders( decoder_t * );
 160 static int  ProcessInitialHeader ( decoder_t *, ogg_packet * );
 161 static block_t *ProcessPacket( decoder_t *, ogg_packet *, block_t * );
 162
 163 static block_t *DecodePacket( decoder_t *, ogg_packet *, int, vlc_tick_t );
 164
 165 /*****************************************************************************
 166  * OpenDecoder: probe the decoder and return score
 167  *****************************************************************************/
 168 static int OpenDecoder( vlc_object_t *p_this )
 169 {
 170     decoder_t *p_dec = (decoder_t*)p_this;
 171     decoder_sys_t *p_sys;
 172
 173     if( p_dec->fmt_in.i_codec != VLC_CODEC_OPUS )
 174         return VLC_EGENERIC;
 175
 176     /* Allocate the memory needed to store the decoder's structure */
 177     if( ( p_dec->p_sys = p_sys = malloc(sizeof(decoder_sys_t)) ) == NULL )
 178         return VLC_ENOMEM;
 179     p_sys->b_has_headers = false;
 180
 181     date_Set( &p_sys->end_date, VLC_TICK_INVALID );
 182
 183     /* Set output properties */
 184     p_dec->fmt_out.i_codec = VLC_CODEC_FL32;
 185
 186     p_dec->pf_decode    = DecodeAudio;
 187     p_dec->pf_flush     = Flush;
 188
 189     p_sys->p_st = NULL;
 190
 191     return VLC_SUCCESS;
 192 }
 193
 194 /****************************************************************************
 195  * DecodeBlock: the whole thing
 196  ****************************************************************************
 197  * This function must be fed with ogg packets.
 198  ****************************************************************************/
 199 static block_t *DecodeBlock( decoder_t *p_dec, block_t *p_block )
 200 {
 201     decoder_sys_t *p_sys = p_dec->p_sys;
 202     ogg_packet oggpacket;
 203
 204     /* Block to Ogg packet */
 205     oggpacket.packet = p_block->p_buffer;
 206     oggpacket.bytes = p_block->i_buffer;
 207
 208     oggpacket.granulepos = -1;
 209     oggpacket.b_o_s = 0;
 210     oggpacket.e_o_s = 0;
 211     oggpacket.packetno = 0;
 212
 213     /* Check for headers */
 214     if( !p_sys->b_has_headers )
 215     {
 216         if( ProcessHeaders( p_dec ) )
 217         {
 218             block_Release( p_block );
 219             return NULL;
 220         }
 221         p_sys->b_has_headers = true;
 222     }
 223
 224     return ProcessPacket( p_dec, &oggpacket, p_block );
 225 }
 226
 227 static int DecodeAudio( decoder_t *p_dec, block_t *p_block )
 228 {
 229     if( p_block == NULL ) /* No Drain */
 230         return VLCDEC_SUCCESS;
 231
 232     p_block = DecodeBlock( p_dec, p_block );
 233     if( p_block != NULL )
 234         decoder_QueueAudio( p_dec, p_block );
 235     return VLCDEC_SUCCESS;
 236 }
 237
 238 /*****************************************************************************
 239  * ProcessHeaders: process Opus headers.
 240  *****************************************************************************/
 241 static int ProcessHeaders( decoder_t *p_dec )
 242 {
 243     ogg_packet oggpacket;
 244
 245     unsigned pi_size[XIPH_MAX_HEADER_COUNT];
 246     void     *pp_data[XIPH_MAX_HEADER_COUNT];
 247     unsigned i_count;
 248
 249     int i_extra = p_dec->fmt_in.i_extra;
 250     uint8_t *p_extra = p_dec->fmt_in.p_extra;
 251
 252     /* If we have no header (e.g. from RTP), make one. */
 253     bool b_dummy_header = false;
 254     if( !i_extra ||
 255         (i_extra > 10 && memcmp( &p_extra[2], "OpusHead", 8 )) ) /* Borked muxers */
 256     {
 257         OpusHeader header;
 258         opus_prepare_header( p_dec->fmt_in.audio.i_channels,
 259                              p_dec->fmt_in.audio.i_rate, &header );
 260         if( opus_write_header( &p_extra, &i_extra, &header,
 261                                opus_get_version_string() ) )
 262             return VLC_ENOMEM;
 263         b_dummy_header = true;
 264     }
 265
 266     if( xiph_SplitHeaders( pi_size, pp_data, &i_count,
 267                            i_extra, p_extra ) )
 268     {
 269         if( b_dummy_header )
 270             free( p_extra );
 271         return VLC_EGENERIC;
 272     }
 273
 274     if( i_count < 2 )
 275     {
 276         if( b_dummy_header )
 277             free( p_extra );
 278         return VLC_EGENERIC;
 279     }
 280
 281     oggpacket.granulepos = -1;
 282     oggpacket.e_o_s = 0;
 283     oggpacket.packetno = 0;
 284
 285     /* Take care of the initial Opus header */
 286     oggpacket.b_o_s = 1; /* yes this actually is a b_o_s packet :) */
 287     oggpacket.bytes  = pi_size[0];
 288     oggpacket.packet = pp_data[0];
 289     int ret = ProcessInitialHeader( p_dec, &oggpacket );
 290
 291     if (ret != VLC_SUCCESS)
 292         msg_Err( p_dec, "initial Opus header is corrupted" );
 293
 294     if( b_dummy_header )
 295         free( p_extra );
 296
 297     return ret;
 298 }
 299
 300 /*****************************************************************************
 301  * ProcessInitialHeader: processes the inital Opus header packet.
 302  *****************************************************************************/
 303 static int ProcessInitialHeader( decoder_t *p_dec, ogg_packet *p_oggpacket )
 304 {
 305     int err;
 306     unsigned char* p_stream_map;
 307     unsigned char new_stream_map[8];
 308     decoder_sys_t *p_sys = p_dec->p_sys;
 309
 310     OpusHeader *p_header = &p_sys->header;
 311
 312     if( !opus_header_parse((unsigned char *)p_oggpacket->packet,p_oggpacket->bytes,p_header) )
 313     {
 314         msg_Err( p_dec, "cannot read Opus header" );
 315         return VLC_EGENERIC;
 316     }
 317     msg_Dbg( p_dec, "Opus audio with %d channels", p_header->channels);
 318
 319     if((p_header->channels>2 && p_header->channel_mapping==0) ||
 320         (p_header->channels>8 && p_header->channel_mapping==1) ||
 321         (p_header->channels>18 && p_header->channel_mapping==2) ||
 322         p_header->channel_mapping>2)
 323     {
 324         msg_Err( p_dec, "Unsupported channel mapping" );
 325         return VLC_EGENERIC;
 326     }
 327     if (p_header->channel_mapping == 2)
 328     {
 329         int i_order = floor(sqrt(p_header->channels));
 330         int i_nondiegetic = p_header->channels - i_order * i_order;
 331         if (i_nondiegetic != 0 && i_nondiegetic != 2)
 332         {
 333             msg_Err( p_dec, "Unsupported ambisonic channel mapping" );
 334             return VLC_EGENERIC;
 335         }
 336     }
 337
 338     /* Setup the format */
 339     p_dec->fmt_out.audio.i_channels = p_header->channels;
 340     p_dec->fmt_out.audio.i_rate = 48000;
 341
 342     if (p_header->channel_mapping <= 1)
 343     {
 344         p_dec->fmt_out.audio.i_physical_channels =
 345             pi_channels_maps[p_header->channels];
 346
 347         if( p_header->channels>2 )
 348         {
 349             static const uint32_t *pi_ch[6] = { pi_3channels_in, pi_4channels_in,
 350                                                 pi_5channels_in, pi_6channels_in,
 351                                                 pi_7channels_in, pi_8channels_in };
 352             uint8_t pi_chan_table[AOUT_CHAN_MAX];
 353
 354             aout_CheckChannelReorder( pi_ch[p_header->channels-3], NULL,
 355                                       p_dec->fmt_out.audio.i_physical_channels,
 356                                       pi_chan_table );
 357             for(int i=0;i<p_header->channels;i++)
 358                 new_stream_map[pi_chan_table[i]]=p_header->stream_map[i];
 359
 360             p_stream_map = new_stream_map;
 361         }
 362         else
 363             p_stream_map = p_header->stream_map;
 364     }
 365     else //p_header->channel_mapping == 2
 366     {
 367         p_dec->fmt_out.audio.channel_type = AUDIO_CHANNEL_TYPE_AMBISONICS;
 368         p_stream_map = p_header->stream_map;
 369     }
 370
 371     /* Opus decoder init */
 372     p_sys->p_st = opus_multistream_decoder_create( 48000, p_header->channels,
 373                     p_header->nb_streams, p_header->nb_coupled,
 374                     p_stream_map,
 375                     &err );
 376     if( !p_sys->p_st || err!=OPUS_OK )
 377     {
 378         msg_Err( p_dec, "decoder initialization failed" );
 379         return VLC_EGENERIC;
 380     }
 381
 382 #ifdef OPUS_SET_GAIN
 383     if( opus_multistream_decoder_ctl( p_sys->p_st,OPUS_SET_GAIN(p_header->gain) ) != OPUS_OK )
 384     {
 385         msg_Err( p_dec, "OPUS_SET_GAIN failed" );
 386         opus_multistream_decoder_destroy( p_sys->p_st );
 387         return VLC_EGENERIC;
 388     }
 389 #endif
 390
 391     date_Init( &p_sys->end_date, 48000, 1 );
 392
 393     return VLC_SUCCESS;
 394 }
 395
 396 /*****************************************************************************
 397  * Flush:
 398  *****************************************************************************/
 399 static void Flush( decoder_t *p_dec )
 400 {
 401     decoder_sys_t *p_sys = p_dec->p_sys;
 402
 403     date_Set( &p_sys->end_date, VLC_TICK_INVALID );
 404 }
 405
 406 /*****************************************************************************
 407  * ProcessPacket: processes a Opus packet.
 408  *****************************************************************************/
 409 static block_t *ProcessPacket( decoder_t *p_dec, ogg_packet *p_oggpacket,
 410                                block_t *p_block )
 411 {
 412     decoder_sys_t *p_sys = p_dec->p_sys;
 413
 414     if( p_block->i_flags & (BLOCK_FLAG_CORRUPTED|BLOCK_FLAG_DISCONTINUITY) )
 415     {
 416         Flush( p_dec );
 417         if( p_block->i_flags & BLOCK_FLAG_CORRUPTED )
 418         {
 419             block_Release( p_block );
 420             return NULL;
 421         }
 422     }
 423
 424     /* Date management */
 425     if( p_block->i_pts != VLC_TICK_INVALID &&
 426         p_block->i_pts != date_Get( &p_sys->end_date ) )
 427     {
 428         date_Set( &p_sys->end_date, p_block->i_pts );
 429     }
 430
 431     if( date_Get( &p_sys->end_date ) == VLC_TICK_INVALID )
 432     {
 433         /* We've just started the stream, wait for the first PTS. */
 434         block_Release( p_block );
 435         return NULL;
 436     }
 437
 438     /* trimming info */
 439     vlc_tick_t i_max_duration = (p_block->i_flags & BLOCK_FLAG_END_OF_SEQUENCE) ?
 440                              p_block->i_length : 0;
 441
 442     block_t *p_aout_buffer = DecodePacket( p_dec, p_oggpacket,
 443                                            p_block->i_nb_samples,
 444                                            i_max_duration );
 445
 446     block_Release( p_block );
 447     return p_aout_buffer;
 448 }
 449
 450 /*****************************************************************************
 451  * DecodePacket: decodes a Opus packet.
 452  *****************************************************************************/
 453 static block_t *DecodePacket( decoder_t *p_dec, ogg_packet *p_oggpacket,
 454                               int i_nb_samples, vlc_tick_t i_duration )
 455 {
 456     decoder_sys_t *p_sys = p_dec->p_sys;
 457
 458     if( !p_oggpacket->bytes )
 459         return NULL;
 460
 461     int spp;
 462     spp=opus_packet_get_nb_frames(p_oggpacket->packet,p_oggpacket->bytes);
 463     if(spp>0)spp*=opus_packet_get_samples_per_frame(p_oggpacket->packet,48000);
 464     if(spp<120||spp>120*48)return NULL;
 465
 466     /* Since the information isn't always available at the demux level
 467      * use the packet's sample number */
 468     if(!i_nb_samples)
 469         i_nb_samples = spp;
 470
 471     if( decoder_UpdateAudioFormat( p_dec ) )
 472         return NULL;
 473     block_t *p_aout_buffer=decoder_NewAudioBuffer( p_dec, spp );
 474     if ( !p_aout_buffer )
 475     {
 476         msg_Err(p_dec, "Oops: No new buffer was returned!");
 477         return NULL;
 478     }
 479
 480     spp=opus_multistream_decode_float(p_sys->p_st, p_oggpacket->packet,
 481          p_oggpacket->bytes, (float *)p_aout_buffer->p_buffer, spp, 0);
 482
 483     int i_end_trim = 0;
 484     if( i_duration > 0 && spp > 0 &&
 485         i_duration < vlc_tick_from_samples(i_nb_samples, 48000) )
 486     {
 487         i_end_trim = spp - VLC_CLIP(samples_from_vlc_tick(i_duration, 48000), 0, spp);
 488     }
 489
 490     if( spp < 0 || i_nb_samples <= 0 || i_end_trim >= i_nb_samples)
 491     {
 492         block_Release(p_aout_buffer);
 493         if( spp < 0 )
 494             msg_Err( p_dec, "Error: corrupted stream?" );
 495         return NULL;
 496     }
 497
 498     p_aout_buffer->i_buffer = (i_nb_samples - i_end_trim) *
 499                               p_sys->header.channels * sizeof(float);
 500
 501     if( spp > i_nb_samples )
 502     {
 503         memmove(p_aout_buffer->p_buffer,
 504             p_aout_buffer->p_buffer
 505             + (spp - i_nb_samples)*p_sys->header.channels*sizeof(float),
 506             p_aout_buffer->i_buffer);
 507     }
 508     i_nb_samples -= i_end_trim;
 509
 510 #ifndef OPUS_SET_GAIN
 511     if(p_sys->header.gain!=0)
 512     {
 513         float gain = pow(10., p_sys->header.gain/5120.);
 514         float *buf =(float *)p_aout_buffer->p_buffer;
 515         for( int i = 0; i < i_nb_samples*p_sys->header.channels; i++)
 516             buf[i] *= gain;
 517     }
 518 #endif
 519     p_aout_buffer->i_nb_samples = i_nb_samples;
 520     p_aout_buffer->i_pts = date_Get( &p_sys->end_date );
 521     p_aout_buffer->i_length = date_Increment( &p_sys->end_date, i_nb_samples )
 522         - p_aout_buffer->i_pts;
 523     return p_aout_buffer;
 524 }
 525
 526 /*****************************************************************************
 527  * CloseDecoder: Opus decoder destruction
 528  *****************************************************************************/
 529 static void CloseDecoder( vlc_object_t *p_this )
 530 {
 531     decoder_t * p_dec = (decoder_t *)p_this;
 532     decoder_sys_t *p_sys = p_dec->p_sys;
 533
 534     if( p_sys->p_st ) opus_multistream_decoder_destroy(p_sys->p_st);
 535
 536     free( p_sys );
 537 }
 538
 539 #ifdef ENABLE_SOUT
 540
 541 /* only ever encode 20 ms at a time, going longer doesn't yield much compression
 542    gain, shorter does have a compression loss, and doesn't matter so much in
 543    Ogg, unless you really need low latency, which would also require muxing one
 544    packet per page. */
 545 static const unsigned OPUS_FRAME_SIZE = 960; /* 48000 * 20 / 1000 */
 546
 547 typedef struct
 548 {
 549     OpusMSEncoder *enc;
 550     float *buffer;
 551     unsigned i_nb_samples;
 552     int i_samples_delay;
 553     block_t *padding;
 554     int nb_streams;
 555 } encoder_sys_t;
 556
 557 static unsigned fill_buffer(encoder_t *enc, unsigned src_start, block_t *src,
 558                             unsigned samples)
 559 {
 560     encoder_sys_t *p_sys = enc->p_sys;
 561     const unsigned channels = enc->fmt_out.audio.i_channels;
 562     const float *src_buf = ((const float *) src->p_buffer) + src_start;
 563     float *dest_buf = p_sys->buffer + (p_sys->i_nb_samples * channels);
 564     const unsigned len = samples * channels;
 565
 566     memcpy(dest_buf, src_buf, len * sizeof(float));
 567
 568     p_sys->i_nb_samples += samples;
 569     src_start += len;
 570
 571     src->i_nb_samples -= samples;
 572     return src_start;
 573 }
 574
 575 static block_t *Encode(encoder_t *enc, block_t *buf)
 576 {
 577     encoder_sys_t *sys = enc->p_sys;
 578
 579     if (!buf)
 580         return NULL;
 581
 582     vlc_tick_t i_pts = buf->i_pts -
 583                 vlc_tick_from_samples( sys->i_samples_delay,
 584                              enc->fmt_in.audio.i_rate );
 585
 586     sys->i_samples_delay += buf->i_nb_samples;
 587
 588     block_t *result = NULL;
 589     unsigned src_start = 0;
 590     unsigned padding_start = 0;
 591     /* The maximum Opus frame size is 1275 bytes + TOC sequence length. */
 592     const unsigned OPUS_MAX_ENCODED_BYTES = ((1275 + 3) * sys->nb_streams) - 2;
 593
 594     while (sys->i_nb_samples + buf->i_nb_samples >= OPUS_FRAME_SIZE)
 595     {
 596         block_t *out_block = block_Alloc(OPUS_MAX_ENCODED_BYTES);
 597
 598         /* add padding to beginning */
 599         if (sys->padding)
 600         {
 601             const size_t leftover_space = OPUS_FRAME_SIZE - sys->i_nb_samples;
 602             padding_start = fill_buffer(enc, padding_start, sys->padding,
 603                     __MIN(sys->padding->i_nb_samples, leftover_space));
 604             if (sys->padding->i_nb_samples <= 0)
 605             {
 606                 block_Release(sys->padding);
 607                 sys->padding = NULL;
 608             }
 609         }
 610
 611         /* padding may have been freed either before or inside previous
 612          * if-statement */
 613         if (!sys->padding)
 614         {
 615             const size_t leftover_space = OPUS_FRAME_SIZE - sys->i_nb_samples;
 616             src_start = fill_buffer(enc, src_start, buf,
 617                     __MIN(buf->i_nb_samples, leftover_space));
 618         }
 619
 620         opus_int32 bytes_encoded = opus_multistream_encode_float(sys->enc, sys->buffer,
 621                 OPUS_FRAME_SIZE, out_block->p_buffer, out_block->i_buffer);
 622
 623         if (bytes_encoded < 0)
 624         {
 625             block_Release(out_block);
 626         }
 627         else
 628         {
 629             out_block->i_length = vlc_tick_from_samples( OPUS_FRAME_SIZE,
 630                                                          enc->fmt_in.audio.i_rate );
 631
 632             out_block->i_dts = out_block->i_pts = i_pts;
 633
 634             sys->i_samples_delay -= OPUS_FRAME_SIZE;
 635
 636             i_pts += out_block->i_length;
 637
 638             sys->i_nb_samples = 0;
 639
 640             out_block->i_buffer = bytes_encoded;
 641             block_ChainAppend(&result, out_block);
 642         }
 643     }
 644
 645     /* put leftover samples at beginning of buffer */
 646     if (buf->i_nb_samples > 0)
 647         fill_buffer(enc, src_start, buf, buf->i_nb_samples);
 648
 649     return result;
 650 }
 651
 652 static int OpenEncoder(vlc_object_t *p_this)
 653 {
 654     encoder_t *enc = (encoder_t *)p_this;
 655
 656     if (enc->fmt_out.i_codec != VLC_CODEC_OPUS)
 657         return VLC_EGENERIC;
 658
 659     encoder_sys_t *sys = malloc(sizeof(*sys));
 660     if (!sys)
 661         return VLC_ENOMEM;
 662
 663     int status = VLC_SUCCESS;
 664     sys->buffer = NULL;
 665     sys->enc = NULL;
 666
 667     enc->pf_encode_audio = Encode;
 668     enc->fmt_in.i_codec = VLC_CODEC_FL32;
 669     enc->fmt_in.audio.i_rate = /* Only 48kHz */
 670     enc->fmt_out.audio.i_rate = 48000;
 671     enc->fmt_out.audio.i_channels = enc->fmt_in.audio.i_channels;
 672
 673     OpusHeader header;
 674
 675     opus_prepare_header(enc->fmt_out.audio.i_channels,
 676             enc->fmt_out.audio.i_rate, &header);
 677
 678     /* needed for max encoded size calculation */
 679     sys->nb_streams = header.nb_streams;
 680
 681     int err;
 682     sys->enc =
 683         opus_multistream_surround_encoder_create(enc->fmt_in.audio.i_rate,
 684                 enc->fmt_in.audio.i_channels, header.channel_mapping,
 685                 &header.nb_streams, &header.nb_coupled, header.stream_map,
 686                 OPUS_APPLICATION_AUDIO, &err);
 687
 688     if (err != OPUS_OK)
 689     {
 690         msg_Err(enc, "Could not create encoder: error %d", err);
 691         sys->enc = NULL;
 692         status = VLC_EGENERIC;
 693         goto error;
 694     }
 695
 696     /* TODO: vbr, fec */
 697
 698     if( enc->fmt_out.i_bitrate )
 699         opus_multistream_encoder_ctl(sys->enc, OPUS_SET_BITRATE( enc->fmt_out.i_bitrate ));
 700
 701     /* Buffer for incoming audio, since opus only accepts frame sizes that are
 702        multiples of 2.5ms */
 703     enc->p_sys = sys;
 704     sys->buffer = vlc_alloc(header.channels, sizeof(float) * OPUS_FRAME_SIZE);
 705     if (!sys->buffer) {
 706         status = VLC_ENOMEM;
 707         goto error;
 708     }
 709
 710     sys->i_nb_samples = 0;
 711
 712     sys->i_samples_delay = 0;
 713     int ret = opus_multistream_encoder_ctl(sys->enc,
 714             OPUS_GET_LOOKAHEAD(&sys->i_samples_delay));
 715     if (ret != OPUS_OK)
 716         msg_Err(enc, "Unable to get number of lookahead samples: %s\n",
 717                 opus_strerror(ret));
 718
 719     header.preskip = sys->i_samples_delay;
 720
 721     /* Now that we have preskip, we can write the header to extradata */
 722     if (opus_write_header((uint8_t **) &enc->fmt_out.p_extra,
 723                           &enc->fmt_out.i_extra, &header, opus_get_version_string()))
 724     {
 725         msg_Err(enc, "Failed to write header.");
 726         status = VLC_ENOMEM;
 727         goto error;
 728     }
 729
 730     if (sys->i_samples_delay > 0)
 731     {
 732         const unsigned padding_samples = sys->i_samples_delay *
 733             enc->fmt_out.audio.i_channels;
 734         sys->padding = block_Alloc(padding_samples * sizeof(float));
 735         if (!sys->padding) {
 736             status = VLC_ENOMEM;
 737             goto error;
 738         }
 739         sys->padding->i_nb_samples = sys->i_samples_delay;
 740         float *pad_ptr = (float *) sys->padding->p_buffer;
 741         memset(pad_ptr, 0, padding_samples * sizeof(float));
 742     }
 743     else
 744     {
 745         sys->padding = NULL;
 746     }
 747
 748     return status;
 749
 750 error:
 751     if (sys->enc)
 752         opus_multistream_encoder_destroy(sys->enc);
 753     free(sys->buffer);
 754     free(sys);
 755     return status;
 756 }
 757
 758 static void CloseEncoder(vlc_object_t *p_this)
 759 {
 760     encoder_t *enc = (encoder_t *)p_this;
 761     encoder_sys_t *sys = enc->p_sys;
 762
 763     opus_multistream_encoder_destroy(sys->enc);
 764     if (sys->padding)
 765         block_Release(sys->padding);
 766     free(sys->buffer);
 767     free(sys);
 768 }
 769 #endif /* ENABLE_SOUT */