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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. static int ff_mlp_get_major_sync_size(const uint8_t * buf, int bufsize)
  123. {
  124.     int has_extension, extensions = 0;
  125.     int size = 28;
  126.     if (bufsize < 28)
  127.         return -1;
  128.  
  129.     if (AV_RB32(buf) == 0xf8726fba) {
  130.         has_extension = buf[25] & 1;
  131.         if (has_extension) {
  132.             extensions = buf[26] >> 4;
  133.             size += 2 + extensions * 2;
  134.         }
  135.     }
  136.     return size;
  137. }
  138.  
  139. /** Read a major sync info header - contains high level information about
  140.  *  the stream - sample rate, channel arrangement etc. Most of this
  141.  *  information is not actually necessary for decoding, only for playback.
  142.  *  gb must be a freshly initialized GetBitContext with no bits read.
  143.  */
  144.  
  145. int ff_mlp_read_major_sync(void *log, MLPHeaderInfo *mh, GetBitContext *gb)
  146. {
  147.     int ratebits, channel_arrangement, header_size;
  148.     uint16_t checksum;
  149.  
  150.     av_assert1(get_bits_count(gb) == 0);
  151.  
  152.     header_size = ff_mlp_get_major_sync_size(gb->buffer, gb->size_in_bits >> 3);
  153.     if (header_size < 0 || gb->size_in_bits < header_size << 3) {
  154.         av_log(log, AV_LOG_ERROR, "packet too short, unable to read major sync\n");
  155.         return -1;
  156.     }
  157.  
  158.     checksum = ff_mlp_checksum16(gb->buffer, header_size - 2);
  159.     if (checksum != AV_RL16(gb->buffer+header_size-2)) {
  160.         av_log(log, AV_LOG_ERROR, "major sync info header checksum error\n");
  161.         return AVERROR_INVALIDDATA;
  162.     }
  163.  
  164.     if (get_bits_long(gb, 24) != 0xf8726f) /* Sync words */
  165.         return AVERROR_INVALIDDATA;
  166.  
  167.     mh->stream_type = get_bits(gb, 8);
  168.     mh->header_size = header_size;
  169.  
  170.     if (mh->stream_type == 0xbb) {
  171.         mh->group1_bits = mlp_quants[get_bits(gb, 4)];
  172.         mh->group2_bits = mlp_quants[get_bits(gb, 4)];
  173.  
  174.         ratebits = get_bits(gb, 4);
  175.         mh->group1_samplerate = mlp_samplerate(ratebits);
  176.         mh->group2_samplerate = mlp_samplerate(get_bits(gb, 4));
  177.  
  178.         skip_bits(gb, 11);
  179.  
  180.         mh->channel_arrangement=
  181.         channel_arrangement    = get_bits(gb, 5);
  182.         mh->channels_mlp       = mlp_channels[channel_arrangement];
  183.         mh->channel_layout_mlp = ff_mlp_layout[channel_arrangement];
  184.     } else if (mh->stream_type == 0xba) {
  185.         mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?
  186.         mh->group2_bits = 0;
  187.  
  188.         ratebits = get_bits(gb, 4);
  189.         mh->group1_samplerate = mlp_samplerate(ratebits);
  190.         mh->group2_samplerate = 0;
  191.  
  192.         skip_bits(gb, 4);
  193.  
  194.         mh->channel_modifier_thd_stream0 = get_bits(gb, 2);
  195.         mh->channel_modifier_thd_stream1 = get_bits(gb, 2);
  196.  
  197.         mh->channel_arrangement=
  198.         channel_arrangement            = get_bits(gb, 5);
  199.         mh->channels_thd_stream1       = truehd_channels(channel_arrangement);
  200.         mh->channel_layout_thd_stream1 = ff_truehd_layout(channel_arrangement);
  201.  
  202.         mh->channel_modifier_thd_stream2 = get_bits(gb, 2);
  203.  
  204.         channel_arrangement            = get_bits(gb, 13);
  205.         mh->channels_thd_stream2       = truehd_channels(channel_arrangement);
  206.         mh->channel_layout_thd_stream2 = ff_truehd_layout(channel_arrangement);
  207.     } else
  208.         return AVERROR_INVALIDDATA;
  209.  
  210.     mh->access_unit_size = 40 << (ratebits & 7);
  211.     mh->access_unit_size_pow2 = 64 << (ratebits & 7);
  212.  
  213.     skip_bits_long(gb, 48);
  214.  
  215.     mh->is_vbr = get_bits1(gb);
  216.  
  217.     mh->peak_bitrate = (get_bits(gb, 15) * mh->group1_samplerate + 8) >> 4;
  218.  
  219.     mh->num_substreams = get_bits(gb, 4);
  220.  
  221.     skip_bits_long(gb, 4 + (header_size - 17) * 8);
  222.  
  223.     return 0;
  224. }
  225.  
  226. typedef struct MLPParseContext
  227. {
  228.     ParseContext pc;
  229.  
  230.     int bytes_left;
  231.  
  232.     int in_sync;
  233.  
  234.     int num_substreams;
  235. } MLPParseContext;
  236.  
  237. static av_cold int mlp_init(AVCodecParserContext *s)
  238. {
  239.     ff_mlp_init_crc();
  240.     return 0;
  241. }
  242.  
  243. static int mlp_parse(AVCodecParserContext *s,
  244.                      AVCodecContext *avctx,
  245.                      const uint8_t **poutbuf, int *poutbuf_size,
  246.                      const uint8_t *buf, int buf_size)
  247. {
  248.     MLPParseContext *mp = s->priv_data;
  249.     int sync_present;
  250.     uint8_t parity_bits;
  251.     int next;
  252.     int ret;
  253.     int i, p = 0;
  254.  
  255.     *poutbuf_size = 0;
  256.     if (buf_size == 0)
  257.         return 0;
  258.  
  259.     if (!mp->in_sync) {
  260.         // Not in sync - find a major sync header
  261.  
  262.         for (i = 0; i < buf_size; i++) {
  263.             mp->pc.state = (mp->pc.state << 8) | buf[i];
  264.             if ((mp->pc.state & 0xfffffffe) == 0xf8726fba &&
  265.                 // ignore if we do not have the data for the start of header
  266.                 mp->pc.index + i >= 7) {
  267.                 mp->in_sync = 1;
  268.                 mp->bytes_left = 0;
  269.                 break;
  270.             }
  271.         }
  272.  
  273.         if (!mp->in_sync) {
  274.             if (ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size) != -1)
  275.                 av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");
  276.             return buf_size;
  277.         }
  278.  
  279.         if ((ret = ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size)) < 0) {
  280.             av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");
  281.             return ret;
  282.         }
  283.  
  284.         return i - 7;
  285.     }
  286.  
  287.     if (mp->bytes_left == 0) {
  288.         // Find length of this packet
  289.  
  290.         /* Copy overread bytes from last frame into buffer. */
  291.         for(; mp->pc.overread>0; mp->pc.overread--) {
  292.             mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];
  293.         }
  294.  
  295.         if (mp->pc.index + buf_size < 2) {
  296.             if (ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size) != -1)
  297.                 av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");
  298.             return buf_size;
  299.         }
  300.  
  301.         mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)
  302.                        |  (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);
  303.         mp->bytes_left = (mp->bytes_left & 0xfff) * 2;
  304.         if (mp->bytes_left <= 0) { // prevent infinite loop
  305.             goto lost_sync;
  306.         }
  307.         mp->bytes_left -= mp->pc.index;
  308.     }
  309.  
  310.     next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;
  311.  
  312.     if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {
  313.         mp->bytes_left -= buf_size;
  314.         return buf_size;
  315.     }
  316.  
  317.     mp->bytes_left = 0;
  318.  
  319.     sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;
  320.  
  321.     if (!sync_present) {
  322.         /* The first nibble of a frame is a parity check of the 4-byte
  323.          * access unit header and all the 2- or 4-byte substream headers. */
  324.         // Only check when this isn't a sync frame - syncs have a checksum.
  325.  
  326.         parity_bits = 0;
  327.         for (i = -1; i < mp->num_substreams; i++) {
  328.             parity_bits ^= buf[p++];
  329.             parity_bits ^= buf[p++];
  330.  
  331.             if (i < 0 || buf[p-2] & 0x80) {
  332.                 parity_bits ^= buf[p++];
  333.                 parity_bits ^= buf[p++];
  334.             }
  335.         }
  336.  
  337.         if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {
  338.             av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");
  339.             goto lost_sync;
  340.         }
  341.     } else {
  342.         GetBitContext gb;
  343.         MLPHeaderInfo mh;
  344.  
  345.         init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);
  346.         if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)
  347.             goto lost_sync;
  348.  
  349.         avctx->bits_per_raw_sample = mh.group1_bits;
  350.         if (avctx->bits_per_raw_sample > 16)
  351.             avctx->sample_fmt = AV_SAMPLE_FMT_S32;
  352.         else
  353.             avctx->sample_fmt = AV_SAMPLE_FMT_S16;
  354.         avctx->sample_rate = mh.group1_samplerate;
  355.         s->duration = mh.access_unit_size;
  356.  
  357.         if(!avctx->channels || !avctx->channel_layout) {
  358.         if (mh.stream_type == 0xbb) {
  359.             /* MLP stream */
  360. #if FF_API_REQUEST_CHANNELS
  361. FF_DISABLE_DEPRECATION_WARNINGS
  362.             if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
  363.                 mh.num_substreams > 1) {
  364.                 avctx->channels       = 2;
  365.                 avctx->channel_layout = AV_CH_LAYOUT_STEREO;
  366. FF_ENABLE_DEPRECATION_WARNINGS
  367.             } else
  368. #endif
  369.             if (avctx->request_channel_layout &&
  370.                 (avctx->request_channel_layout & AV_CH_LAYOUT_STEREO) ==
  371.                 avctx->request_channel_layout &&
  372.                 mh.num_substreams > 1) {
  373.                 avctx->channels       = 2;
  374.                 avctx->channel_layout = AV_CH_LAYOUT_STEREO;
  375.             } else {
  376.                 avctx->channels       = mh.channels_mlp;
  377.                 avctx->channel_layout = mh.channel_layout_mlp;
  378.             }
  379.         } else { /* mh.stream_type == 0xba */
  380.             /* TrueHD stream */
  381. #if FF_API_REQUEST_CHANNELS
  382. FF_DISABLE_DEPRECATION_WARNINGS
  383.             if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
  384.                 mh.num_substreams > 1) {
  385.                 avctx->channels       = 2;
  386.                 avctx->channel_layout = AV_CH_LAYOUT_STEREO;
  387.             } else if (avctx->request_channels > 0 &&
  388.                        avctx->request_channels <= mh.channels_thd_stream1) {
  389.                 avctx->channels       = mh.channels_thd_stream1;
  390.                 avctx->channel_layout = mh.channel_layout_thd_stream1;
  391. FF_ENABLE_DEPRECATION_WARNINGS
  392.             } else
  393. #endif
  394.                 if (avctx->request_channel_layout &&
  395.                     (avctx->request_channel_layout & AV_CH_LAYOUT_STEREO) ==
  396.                     avctx->request_channel_layout &&
  397.                     mh.num_substreams > 1) {
  398.                 avctx->channels       = 2;
  399.                 avctx->channel_layout = AV_CH_LAYOUT_STEREO;
  400.             } else if (!mh.channels_thd_stream2 ||
  401.                        (avctx->request_channel_layout &&
  402.                         (avctx->request_channel_layout & mh.channel_layout_thd_stream1) ==
  403.                         avctx->request_channel_layout)) {
  404.                 avctx->channels       = mh.channels_thd_stream1;
  405.                 avctx->channel_layout = mh.channel_layout_thd_stream1;
  406.             } else {
  407.                 avctx->channels       = mh.channels_thd_stream2;
  408.                 avctx->channel_layout = mh.channel_layout_thd_stream2;
  409.             }
  410.         }
  411.         }
  412.  
  413.         if (!mh.is_vbr) /* Stream is CBR */
  414.             avctx->bit_rate = mh.peak_bitrate;
  415.  
  416.         mp->num_substreams = mh.num_substreams;
  417.     }
  418.  
  419.     *poutbuf = buf;
  420.     *poutbuf_size = buf_size;
  421.  
  422.     return next;
  423.  
  424. lost_sync:
  425.     mp->in_sync = 0;
  426.     return 1;
  427. }
  428.  
  429. AVCodecParser ff_mlp_parser = {
  430.     .codec_ids      = { AV_CODEC_ID_MLP, AV_CODEC_ID_TRUEHD },
  431.     .priv_data_size = sizeof(MLPParseContext),
  432.     .parser_init    = mlp_init,
  433.     .parser_parse   = mlp_parse,
  434.     .parser_close   = ff_parse_close,
  435. };
  436.