libavformat/dtsdec.c

   1 /*
   2  * RAW DTS demuxer
   3  * Copyright (c) 2008 Benjamin Larsson
   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 #include "libavutil/crc.h"
  23
  24 #include "libavcodec/bytestream.h"
  25 #include "libavcodec/dca.h"
  26 #include "libavcodec/dca_syncwords.h"
  27 #include "libavcodec/get_bits.h"
  28
  29 #include "avformat.h"
  30 #include "demux.h"
  31 #include "rawdec.h"
  32
  33 static int dts_probe(const AVProbeData *p)
  34 {
  35     const uint8_t *buf, *bufp;
  36     uint32_t state = -1;
  37     int markers[4*16] = {0};
  38     int exss_markers = 0, exss_nextpos = 0;
  39     int sum, max, pos, ret, i;
  40     int64_t diff = 0;
  41     int diffcount = 1;
  42     uint8_t hdr[DCA_CORE_FRAME_HEADER_SIZE + AV_INPUT_BUFFER_PADDING_SIZE] = { 0 };
  43
  44     for (pos = FFMIN(4096, p->buf_size); pos < p->buf_size - 2; pos += 2) {
  45         int marker, wide_hdr, hdr_size, framesize;
  46         DCACoreFrameHeader h;
  47         GetBitContext gb;
  48
  49         bufp = buf = p->buf + pos;
  50         state = (state << 16) | bytestream_get_be16(&bufp);
  51
  52         if (pos >= 4) {
  53             if (AV_RL16(buf) || AV_RL16(buf-4)) {
  54                 diff += FFABS(((int16_t)AV_RL16(buf)) - (int16_t)AV_RL16(buf-4));
  55                 diffcount ++;
  56             }
  57         }
  58
  59         /* extension substream (EXSS) */
  60         if (state == DCA_SYNCWORD_SUBSTREAM) {
  61             if (pos < exss_nextpos)
  62                 continue;
  63
  64             init_get_bits(&gb, buf - 2, 96);
  65             skip_bits_long(&gb, 42);
  66
  67             wide_hdr  = get_bits1(&gb);
  68             hdr_size  = get_bits(&gb,  8 + 4 * wide_hdr) + 1;
  69             framesize = get_bits(&gb, 16 + 4 * wide_hdr) + 1;
  70             if (hdr_size & 3 || framesize & 3)
  71                 continue;
  72             if (hdr_size < 16 || framesize < hdr_size)
  73                 continue;
  74             if (pos - 2 + hdr_size > p->buf_size)
  75                 continue;
  76             if (av_crc(av_crc_get_table(AV_CRC_16_CCITT), 0xffff, buf + 3, hdr_size - 5))
  77                 continue;
  78
  79             if (pos == exss_nextpos)
  80                 exss_markers++;
  81             else
  82                 exss_markers = FFMAX(1, exss_markers - 1);
  83             exss_nextpos = pos + framesize;
  84             continue;
  85         }
  86
  87         /* regular bitstream */
  88         if (state == DCA_SYNCWORD_CORE_BE &&
  89             (bytestream_get_be16(&bufp) & 0xFC00) == 0xFC00)
  90             marker = 0;
  91         else if (state == DCA_SYNCWORD_CORE_LE &&
  92                  (bytestream_get_be16(&bufp) & 0x00FC) == 0x00FC)
  93             marker = 1;
  94
  95         /* 14 bits big-endian bitstream */
  96         else if (state == DCA_SYNCWORD_CORE_14B_BE &&
  97                  (bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
  98             marker = 2;
  99
 100         /* 14 bits little-endian bitstream */
 101         else if (state == DCA_SYNCWORD_CORE_14B_LE &&
 102                  (bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
 103             marker = 3;
 104         else
 105             continue;
 106
 107         if ((ret = avpriv_dca_convert_bitstream(buf - 2, DCA_CORE_FRAME_HEADER_SIZE,
 108                                                 hdr,     DCA_CORE_FRAME_HEADER_SIZE)) < 0)
 109             continue;
 110         if (avpriv_dca_parse_core_frame_header(&h, hdr, ret) < 0)
 111             continue;
 112
 113         marker += 4 * h.sr_code;
 114
 115         markers[marker] ++;
 116     }
 117
 118     if (exss_markers > 3)
 119         return AVPROBE_SCORE_EXTENSION + 1;
 120
 121     sum = max = 0;
 122     for (i=0; i<FF_ARRAY_ELEMS(markers); i++) {
 123         sum += markers[i];
 124         if (markers[max] < markers[i])
 125             max = i;
 126     }
 127
 128     if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
 129         markers[max] * 4 > sum * 3 &&
 130         diff / diffcount > 600)
 131         return AVPROBE_SCORE_EXTENSION + 1;
 132
 133     return 0;
 134 }
 135
 136 const FFInputFormat ff_dts_demuxer = {
 137     .p.name         = "dts",
 138     .p.long_name    = NULL_IF_CONFIG_SMALL("raw DTS"),
 139     .p.flags        = AVFMT_GENERIC_INDEX,
 140     .p.extensions   = "dts",
 141     .p.priv_class   = &ff_raw_demuxer_class,
 142     .read_probe     = dts_probe,
 143     .read_header    = ff_raw_audio_read_header,
 144     .read_packet    = ff_raw_read_partial_packet,
 145     .raw_codec_id   = AV_CODEC_ID_DTS,
 146     .priv_data_size = sizeof(FFRawDemuxerContext),
 147 };