libavformat/shortendec.c

   1 /*
   2  * Shorten demuxer
   3  * Copyright (c) 2001 Fabrice Bellard
   4  * Copyright (c) 2005 Alex Beregszaszi
   5  * Copyright (c) 2015 Carl Eugen Hoyos
   6  *
   7  * This file is part of FFmpeg.
   8  *
   9  * FFmpeg is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * FFmpeg 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 GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with FFmpeg; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include "avformat.h"
  25 #include "rawdec.h"
  26 #include "libavcodec/golomb.h"
  27
  28 static int shn_probe(const AVProbeData *p)
  29 {
  30     GetBitContext gb;
  31     int version, internal_ftype, channels, blocksize;
  32
  33     if (AV_RB32(p->buf) != 0x616a6b67)
  34         return 0;
  35     version = p->buf[4];
  36     if (init_get_bits8(&gb, p->buf + 5, p->buf_size - 5 - AV_INPUT_BUFFER_PADDING_SIZE) < 0)
  37         return 0;
  38     if (!version) {
  39         internal_ftype = get_ur_golomb_shorten(&gb, 4);
  40         channels = get_ur_golomb_shorten(&gb, 0);
  41         blocksize = 256;
  42     } else {
  43         unsigned k;
  44         k = get_ur_golomb_shorten(&gb, 2);
  45         if (k > 31)
  46             return 0;
  47         internal_ftype = get_ur_golomb_shorten(&gb, k);
  48         k = get_ur_golomb_shorten(&gb, 2);
  49         if (k > 31)
  50             return 0;
  51         channels = get_ur_golomb_shorten(&gb, k);
  52         k = get_ur_golomb_shorten(&gb, 2);
  53         if (k > 31)
  54             return 0;
  55         blocksize = get_ur_golomb_shorten(&gb, k);
  56     }
  57
  58     if (internal_ftype != 2 && internal_ftype != 3 && internal_ftype != 5)
  59         return 0;
  60     if (channels < 1 || channels > 8)
  61         return 0;
  62     if (blocksize < 1 || blocksize > 65535)
  63         return 0;
  64
  65     return AVPROBE_SCORE_EXTENSION + 1;
  66 }
  67
  68 FF_RAW_DEMUXER_CLASS(shorten)
  69 AVInputFormat ff_shorten_demuxer = {
  70     .name           = "shn",
  71     .long_name      = NULL_IF_CONFIG_SMALL("raw Shorten"),
  72     .read_probe     = shn_probe,
  73     .read_header    = ff_raw_audio_read_header,
  74     .read_packet    = ff_raw_read_partial_packet,
  75     .flags          = AVFMT_NOBINSEARCH | AVFMT_NOGENSEARCH | AVFMT_NO_BYTE_SEEK | AVFMT_NOTIMESTAMPS,
  76     .extensions     = "shn",
  77     .raw_codec_id   = AV_CODEC_ID_SHORTEN,
  78     .priv_data_size = sizeof(FFRawDemuxerContext),
  79     .priv_class     = &shorten_demuxer_class,
  80 };