libavformat/vocdec.c

   1 /*
   2  * Creative Voice File demuxer.
   3  * Copyright (c) 2006  Aurelien Jacobs <aurel@gnuage.org>
   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 St, Fifth Floor, Boston, MA  02110-1301  USA
  20  */
  21
  22 #include "voc.h"
  23
  24
  25 static const int voc_max_pkt_size = 2048;
  26
  27
  28 static int voc_probe(AVProbeData *p)
  29 {
  30     int version, check;
  31
  32     if (p->buf_size < 26)
  33         return 0;
  34     if (memcmp(p->buf, voc_magic, sizeof(voc_magic) - 1))
  35         return 0;
  36     version = p->buf[22] | (p->buf[23] << 8);
  37     check = p->buf[24] | (p->buf[25] << 8);
  38     if (~version + 0x1234 != check)
  39         return 10;
  40
  41     return AVPROBE_SCORE_MAX;
  42 }
  43
  44 static int voc_read_header(AVFormatContext *s, AVFormatParameters *ap)
  45 {
  46     voc_dec_context_t *voc = s->priv_data;
  47     ByteIOContext *pb = &s->pb;
  48     int header_size;
  49     AVStream *st;
  50
  51     url_fskip(pb, 20);
  52     header_size = get_le16(pb) - 22;
  53     if (header_size != 4) {
  54         av_log(s, AV_LOG_ERROR, "unkown header size: %d\n", header_size);
  55         return AVERROR_NOTSUPP;
  56     }
  57     url_fskip(pb, header_size);
  58     st = av_new_stream(s, 0);
  59     if (!st)
  60         return AVERROR_NOMEM;
  61     st->codec->codec_type = CODEC_TYPE_AUDIO;
  62
  63     voc->remaining_size = 0;
  64     return 0;
  65 }
  66
  67 int
  68 voc_get_packet(AVFormatContext *s, AVPacket *pkt, AVStream *st, int max_size)
  69 {
  70     voc_dec_context_t *voc = s->priv_data;
  71     AVCodecContext *dec = st->codec;
  72     ByteIOContext *pb = &s->pb;
  73     voc_type_t type;
  74     int size;
  75     int sample_rate = 0;
  76     int channels = 1;
  77
  78     while (!voc->remaining_size) {
  79         type = get_byte(pb);
  80         if (type == VOC_TYPE_EOF)
  81             return AVERROR_IO;
  82         voc->remaining_size = get_le24(pb);
  83         max_size -= 4;
  84
  85         switch (type) {
  86         case VOC_TYPE_VOICE_DATA:
  87             dec->sample_rate = 1000000 / (256 - get_byte(pb));
  88             if (sample_rate)
  89                 dec->sample_rate = sample_rate;
  90             dec->channels = channels;
  91             dec->codec_id = codec_get_id(voc_codec_tags, get_byte(pb));
  92             dec->bits_per_sample = av_get_bits_per_sample(dec->codec_id);
  93             voc->remaining_size -= 2;
  94             max_size -= 2;
  95             channels = 1;
  96             break;
  97
  98         case VOC_TYPE_VOICE_DATA_CONT:
  99             break;
 100
 101         case VOC_TYPE_EXTENDED:
 102             sample_rate = get_le16(pb);
 103             get_byte(pb);
 104             channels = get_byte(pb) + 1;
 105             sample_rate = 256000000 / (channels * (65536 - sample_rate));
 106             voc->remaining_size = 0;
 107             max_size -= 4;
 108             break;
 109
 110         case VOC_TYPE_NEW_VOICE_DATA:
 111             dec->sample_rate = get_le32(pb);
 112             dec->bits_per_sample = get_byte(pb);
 113             dec->channels = get_byte(pb);
 114             dec->codec_id = codec_get_id(voc_codec_tags, get_le16(pb));
 115             url_fskip(pb, 4);
 116             voc->remaining_size -= 12;
 117             max_size -= 12;
 118             break;
 119
 120         default:
 121             url_fskip(pb, voc->remaining_size);
 122             max_size -= voc->remaining_size;
 123             voc->remaining_size = 0;
 124             break;
 125         }
 126     }
 127
 128     dec->bit_rate = dec->sample_rate * dec->bits_per_sample;
 129
 130     if (max_size <= 0)
 131         max_size = voc_max_pkt_size;
 132     size = FFMIN(voc->remaining_size, max_size);
 133     voc->remaining_size -= size;
 134     return av_get_packet(pb, pkt, size);
 135 }
 136
 137 static int voc_read_packet(AVFormatContext *s, AVPacket *pkt)
 138 {
 139     return voc_get_packet(s, pkt, s->streams[0], 0);
 140 }
 141
 142 static int voc_read_close(AVFormatContext *s)
 143 {
 144     return 0;
 145 }
 146
 147 AVInputFormat voc_demuxer = {
 148     "voc",
 149     "Creative Voice File format",
 150     sizeof(voc_dec_context_t),
 151     voc_probe,
 152     voc_read_header,
 153     voc_read_packet,
 154     voc_read_close,
 155     .codec_tag=(const AVCodecTag*[]){voc_codec_tags, 0},
 156 };