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  1. /*
  2.  * MLP parser
  3.  * Copyright (c) 2007 Ian Caulfield
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. /**
  23.  * @file
  24.  * MLP parser
  25.  */
  26.  
  27. #include <stdint.h>
  28.  
  29. #include "libavutil/channel_layout.h"
  30. #include "libavutil/crc.h"
  31. #include "libavutil/internal.h"
  32. #include "get_bits.h"
  33. #include "parser.h"
  34. #include "mlp_parser.h"
  35. #include "mlp.h"
  36.  
  37. static const uint8_t mlp_quants[16] = {
  38.     16, 20, 24, 0, 0, 0, 0, 0,
  39.      0,  0,  0, 0, 0, 0, 0, 0,
  40. };
  41.  
  42. static const uint8_t mlp_channels[32] = {
  43.     1, 2, 3, 4, 3, 4, 5, 3, 4, 5, 4, 5, 6, 4, 5, 4,
  44.     5, 6, 5, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  45. };
  46.  
  47. const uint64_t ff_mlp_layout[32] = {
  48.     AV_CH_LAYOUT_MONO,
  49.     AV_CH_LAYOUT_STEREO,
  50.     AV_CH_LAYOUT_2_1,
  51.     AV_CH_LAYOUT_QUAD,
  52.     AV_CH_LAYOUT_STEREO|AV_CH_LOW_FREQUENCY,
  53.     AV_CH_LAYOUT_2_1|AV_CH_LOW_FREQUENCY,
  54.     AV_CH_LAYOUT_QUAD|AV_CH_LOW_FREQUENCY,
  55.     AV_CH_LAYOUT_SURROUND,
  56.     AV_CH_LAYOUT_4POINT0,
  57.     AV_CH_LAYOUT_5POINT0_BACK,
  58.     AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,
  59.     AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,
  60.     AV_CH_LAYOUT_5POINT1_BACK,
  61.     AV_CH_LAYOUT_4POINT0,
  62.     AV_CH_LAYOUT_5POINT0_BACK,
  63.     AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,
  64.     AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,
  65.     AV_CH_LAYOUT_5POINT1_BACK,
  66.     AV_CH_LAYOUT_QUAD|AV_CH_LOW_FREQUENCY,
  67.     AV_CH_LAYOUT_5POINT0_BACK,
  68.     AV_CH_LAYOUT_5POINT1_BACK,
  69.     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
  70. };
  71.  
  72. static const uint8_t thd_chancount[13] = {
  73. //  LR    C   LFE  LRs LRvh  LRc LRrs  Cs   Ts  LRsd  LRw  Cvh  LFE2
  74.      2,   1,   1,   2,   2,   2,   2,   1,   1,   2,   2,   1,   1
  75. };
  76.  
  77. static const uint64_t thd_layout[13] = {
  78.     AV_CH_FRONT_LEFT|AV_CH_FRONT_RIGHT,                     // LR
  79.     AV_CH_FRONT_CENTER,                                     // C
  80.     AV_CH_LOW_FREQUENCY,                                    // LFE
  81.     AV_CH_SIDE_LEFT|AV_CH_SIDE_RIGHT,                       // LRs
  82.     AV_CH_TOP_FRONT_LEFT|AV_CH_TOP_FRONT_RIGHT,             // LRvh
  83.     AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER, // LRc
  84.     AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT,                       // LRrs
  85.     AV_CH_BACK_CENTER,                                      // Cs
  86.     AV_CH_TOP_CENTER,                                       // Ts
  87.     AV_CH_SURROUND_DIRECT_LEFT|AV_CH_SURROUND_DIRECT_RIGHT, // LRsd
  88.     AV_CH_WIDE_LEFT|AV_CH_WIDE_RIGHT,                       // LRw
  89.     AV_CH_TOP_FRONT_CENTER,                                 // Cvh
  90.     AV_CH_LOW_FREQUENCY_2,                                  // LFE2
  91. };
  92.  
  93. static int mlp_samplerate(int in)
  94. {
  95.     if (in == 0xF)
  96.         return 0;
  97.  
  98.     return (in & 8 ? 44100 : 48000) << (in & 7) ;
  99. }
  100.  
  101. static int truehd_channels(int chanmap)
  102. {
  103.     int channels = 0, i;
  104.  
  105.     for (i = 0; i < 13; i++)
  106.         channels += thd_chancount[i] * ((chanmap >> i) & 1);
  107.  
  108.     return channels;
  109. }
  110.  
  111. uint64_t ff_truehd_layout(int chanmap)
  112. {
  113.     int i;
  114.     uint64_t layout = 0;
  115.  
  116.     for (i = 0; i < 13; i++)
  117.         layout |= thd_layout[i] * ((chanmap >> i) & 1);
  118.  
  119.     return layout;
  120. }
  121.  
  122. /** Read a major sync info header - contains high level information about
  123.  *  the stream - sample rate, channel arrangement etc. Most of this
  124.  *  information is not actually necessary for decoding, only for playback.
  125.  *  gb must be a freshly initialized GetBitContext with no bits read.
  126.  */
  127.  
  128. int ff_mlp_read_major_sync(void *log, MLPHeaderInfo *mh, GetBitContext *gb)
  129. {
  130.     int ratebits, channel_arrangement;
  131.     uint16_t checksum;
  132.  
  133.     av_assert1(get_bits_count(gb) == 0);
  134.  
  135.     if (gb->size_in_bits < 28 << 3) {
  136.         av_log(log, AV_LOG_ERROR, "packet too short, unable to read major sync\n");
  137.         return -1;
  138.     }
  139.  
  140.     checksum = ff_mlp_checksum16(gb->buffer, 26);
  141.     if (checksum != AV_RL16(gb->buffer+26)) {
  142.         av_log(log, AV_LOG_ERROR, "major sync info header checksum error\n");
  143.         return AVERROR_INVALIDDATA;
  144.     }
  145.  
  146.     if (get_bits_long(gb, 24) != 0xf8726f) /* Sync words */
  147.         return AVERROR_INVALIDDATA;
  148.  
  149.     mh->stream_type = get_bits(gb, 8);
  150.  
  151.     if (mh->stream_type == 0xbb) {
  152.         mh->group1_bits = mlp_quants[get_bits(gb, 4)];
  153.         mh->group2_bits = mlp_quants[get_bits(gb, 4)];
  154.  
  155.         ratebits = get_bits(gb, 4);
  156.         mh->group1_samplerate = mlp_samplerate(ratebits);
  157.         mh->group2_samplerate = mlp_samplerate(get_bits(gb, 4));
  158.  
  159.         skip_bits(gb, 11);
  160.  
  161.         mh->channel_arrangement=
  162.         channel_arrangement    = get_bits(gb, 5);
  163.         mh->channels_mlp       = mlp_channels[channel_arrangement];
  164.         mh->channel_layout_mlp = ff_mlp_layout[channel_arrangement];
  165.     } else if (mh->stream_type == 0xba) {
  166.         mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?
  167.         mh->group2_bits = 0;
  168.  
  169.         ratebits = get_bits(gb, 4);
  170.         mh->group1_samplerate = mlp_samplerate(ratebits);
  171.         mh->group2_samplerate = 0;
  172.  
  173.         skip_bits(gb, 8);
  174.  
  175.         mh->channel_arrangement=
  176.         channel_arrangement            = get_bits(gb, 5);
  177.         mh->channels_thd_stream1       = truehd_channels(channel_arrangement);
  178.         mh->channel_layout_thd_stream1 = ff_truehd_layout(channel_arrangement);
  179.  
  180.         skip_bits(gb, 2);
  181.  
  182.         channel_arrangement            = get_bits(gb, 13);
  183.         mh->channels_thd_stream2       = truehd_channels(channel_arrangement);
  184.         mh->channel_layout_thd_stream2 = ff_truehd_layout(channel_arrangement);
  185.     } else
  186.         return AVERROR_INVALIDDATA;
  187.  
  188.     mh->access_unit_size = 40 << (ratebits & 7);
  189.     mh->access_unit_size_pow2 = 64 << (ratebits & 7);
  190.  
  191.     skip_bits_long(gb, 48);
  192.  
  193.     mh->is_vbr = get_bits1(gb);
  194.  
  195.     mh->peak_bitrate = (get_bits(gb, 15) * mh->group1_samplerate + 8) >> 4;
  196.  
  197.     mh->num_substreams = get_bits(gb, 4);
  198.  
  199.     skip_bits_long(gb, 4 + 11 * 8);
  200.  
  201.     return 0;
  202. }
  203.  
  204. typedef struct MLPParseContext
  205. {
  206.     ParseContext pc;
  207.  
  208.     int bytes_left;
  209.  
  210.     int in_sync;
  211.  
  212.     int num_substreams;
  213. } MLPParseContext;
  214.  
  215. static av_cold int mlp_init(AVCodecParserContext *s)
  216. {
  217.     ff_mlp_init_crc();
  218.     return 0;
  219. }
  220.  
  221. static int mlp_parse(AVCodecParserContext *s,
  222.                      AVCodecContext *avctx,
  223.                      const uint8_t **poutbuf, int *poutbuf_size,
  224.                      const uint8_t *buf, int buf_size)
  225. {
  226.     MLPParseContext *mp = s->priv_data;
  227.     int sync_present;
  228.     uint8_t parity_bits;
  229.     int next;
  230.     int i, p = 0;
  231.  
  232.     *poutbuf_size = 0;
  233.     if (buf_size == 0)
  234.         return 0;
  235.  
  236.     if (!mp->in_sync) {
  237.         // Not in sync - find a major sync header
  238.  
  239.         for (i = 0; i < buf_size; i++) {
  240.             mp->pc.state = (mp->pc.state << 8) | buf[i];
  241.             if ((mp->pc.state & 0xfffffffe) == 0xf8726fba &&
  242.                 // ignore if we do not have the data for the start of header
  243.                 mp->pc.index + i >= 7) {
  244.                 mp->in_sync = 1;
  245.                 mp->bytes_left = 0;
  246.                 break;
  247.             }
  248.         }
  249.  
  250.         if (!mp->in_sync) {
  251.             if (ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size) != -1)
  252.                 av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");
  253.             return buf_size;
  254.         }
  255.  
  256.         ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size);
  257.  
  258.         return i - 7;
  259.     }
  260.  
  261.     if (mp->bytes_left == 0) {
  262.         // Find length of this packet
  263.  
  264.         /* Copy overread bytes from last frame into buffer. */
  265.         for(; mp->pc.overread>0; mp->pc.overread--) {
  266.             mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];
  267.         }
  268.  
  269.         if (mp->pc.index + buf_size < 2) {
  270.             if (ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size) != -1)
  271.                 av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");
  272.             return buf_size;
  273.         }
  274.  
  275.         mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)
  276.                        |  (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);
  277.         mp->bytes_left = (mp->bytes_left & 0xfff) * 2;
  278.         if (mp->bytes_left <= 0) { // prevent infinite loop
  279.             goto lost_sync;
  280.         }
  281.         mp->bytes_left -= mp->pc.index;
  282.     }
  283.  
  284.     next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;
  285.  
  286.     if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {
  287.         mp->bytes_left -= buf_size;
  288.         return buf_size;
  289.     }
  290.  
  291.     mp->bytes_left = 0;
  292.  
  293.     sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;
  294.  
  295.     if (!sync_present) {
  296.         /* The first nibble of a frame is a parity check of the 4-byte
  297.          * access unit header and all the 2- or 4-byte substream headers. */
  298.         // Only check when this isn't a sync frame - syncs have a checksum.
  299.  
  300.         parity_bits = 0;
  301.         for (i = -1; i < mp->num_substreams; i++) {
  302.             parity_bits ^= buf[p++];
  303.             parity_bits ^= buf[p++];
  304.  
  305.             if (i < 0 || buf[p-2] & 0x80) {
  306.                 parity_bits ^= buf[p++];
  307.                 parity_bits ^= buf[p++];
  308.             }
  309.         }
  310.  
  311.         if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
  312.             av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");
  313.             goto lost_sync;
  314.         }
  315.     } else {
  316.         GetBitContext gb;
  317.         MLPHeaderInfo mh;
  318.  
  319.         init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);
  320.         if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)
  321.             goto lost_sync;
  322.  
  323.         avctx->bits_per_raw_sample = mh.group1_bits;
  324.         if (avctx->bits_per_raw_sample > 16)
  325.             avctx->sample_fmt = AV_SAMPLE_FMT_S32;
  326.         else
  327.             avctx->sample_fmt = AV_SAMPLE_FMT_S16;
  328.         avctx->sample_rate = mh.group1_samplerate;
  329.         s->duration = mh.access_unit_size;
  330.  
  331.         if(!avctx->channels || !avctx->channel_layout) {
  332.         if (mh.stream_type == 0xbb) {
  333.             /* MLP stream */
  334. #if FF_API_REQUEST_CHANNELS
  335. FF_DISABLE_DEPRECATION_WARNINGS
  336.             if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
  337.                 mh.num_substreams > 1) {
  338.                 avctx->channels       = 2;
  339.                 avctx->channel_layout = AV_CH_LAYOUT_STEREO;
  340. FF_ENABLE_DEPRECATION_WARNINGS
  341.             } else
  342. #endif
  343.             if (avctx->request_channel_layout == AV_CH_LAYOUT_STEREO &&
  344.                 mh.num_substreams > 1) {
  345.                 avctx->channels       = 2;
  346.                 avctx->channel_layout = AV_CH_LAYOUT_STEREO;
  347.             } else {
  348.                 avctx->channels       = mh.channels_mlp;
  349.                 avctx->channel_layout = mh.channel_layout_mlp;
  350.             }
  351.         } else { /* mh.stream_type == 0xba */
  352.             /* TrueHD stream */
  353. #if FF_API_REQUEST_CHANNELS
  354. FF_DISABLE_DEPRECATION_WARNINGS
  355.             if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
  356.                 mh.num_substreams > 1) {
  357.                 avctx->channels       = 2;
  358.                 avctx->channel_layout = AV_CH_LAYOUT_STEREO;
  359.             } else if (avctx->request_channels > 0 &&
  360.                        avctx->request_channels <= mh.channels_thd_stream1) {
  361.                 avctx->channels       = mh.channels_thd_stream1;
  362.                 avctx->channel_layout = mh.channel_layout_thd_stream1;
  363. FF_ENABLE_DEPRECATION_WARNINGS
  364.             } else
  365. #endif
  366.             if (avctx->request_channel_layout == AV_CH_LAYOUT_STEREO &&
  367.                 mh.num_substreams > 1) {
  368.                 avctx->channels       = 2;
  369.                 avctx->channel_layout = AV_CH_LAYOUT_STEREO;
  370.             } else if (avctx->request_channel_layout == mh.channel_layout_thd_stream1 ||
  371.                        !mh.channels_thd_stream2) {
  372.                 avctx->channels       = mh.channels_thd_stream1;
  373.                 avctx->channel_layout = mh.channel_layout_thd_stream1;
  374.             } else {
  375.                 avctx->channels       = mh.channels_thd_stream2;
  376.                 avctx->channel_layout = mh.channel_layout_thd_stream2;
  377.             }
  378.         }
  379.         }
  380.  
  381.         if (!mh.is_vbr) /* Stream is CBR */
  382.             avctx->bit_rate = mh.peak_bitrate;
  383.  
  384.         mp->num_substreams = mh.num_substreams;
  385.     }
  386.  
  387.     *poutbuf = buf;
  388.     *poutbuf_size = buf_size;
  389.  
  390.     return next;
  391.  
  392. lost_sync:
  393.     mp->in_sync = 0;
  394.     return 1;
  395. }
  396.  
  397. AVCodecParser ff_mlp_parser = {
  398.     .codec_ids      = { AV_CODEC_ID_MLP, AV_CODEC_ID_TRUEHD },
  399.     .priv_data_size = sizeof(MLPParseContext),
  400.     .parser_init    = mlp_init,
  401.     .parser_parse   = mlp_parse,
  402.     .parser_close   = ff_parse_close,
  403. };
  404.