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 Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "libavutil/intreadwrite.h"
  23 #include "demux.h"
  24 #include "voc.h"
  25 #include "internal.h"
  26
  27 static int voc_probe(const AVProbeData *p)
  28 {
  29     int version, check;
  30
  31     if (memcmp(p->buf, ff_voc_magic, sizeof(ff_voc_magic) - 1))
  32         return 0;
  33     version = AV_RL16(p->buf + 22);
  34     check = AV_RL16(p->buf + 24);
  35     if (~version + 0x1234 != check)
  36         return 10;
  37
  38     return AVPROBE_SCORE_MAX;
  39 }
  40
  41 static int voc_read_header(AVFormatContext *s)
  42 {
  43     VocDecContext *voc = s->priv_data;
  44     AVIOContext *pb = s->pb;
  45     int header_size;
  46
  47     avio_skip(pb, 20);
  48     header_size = avio_rl16(pb) - 22;
  49     if (header_size != 4) {
  50         av_log(s, AV_LOG_ERROR, "unknown header size: %d\n", header_size);
  51         return AVERROR(ENOSYS);
  52     }
  53     avio_skip(pb, header_size);
  54
  55     s->ctx_flags |= AVFMTCTX_NOHEADER;
  56
  57     voc->remaining_size = 0;
  58     return 0;
  59 }
  60
  61 static int voc_read_packet(AVFormatContext *s, AVPacket *pkt)
  62 {
  63     if (!s->nb_streams) {
  64         AVStream *st = avformat_new_stream(s, NULL);
  65         if (!st)
  66             return AVERROR(ENOMEM);
  67         st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
  68     }
  69     return ff_voc_get_packet(s, pkt, s->streams[0], 0);
  70 }
  71
  72 static int voc_read_seek(AVFormatContext *s, int stream_index,
  73                          int64_t timestamp, int flags)
  74 {
  75     VocDecContext *voc = s->priv_data;
  76     AVStream *st;
  77     FFStream *sti;
  78     int index;
  79
  80     if (s->nb_streams < 1) {
  81         av_log(s, AV_LOG_ERROR, "cannot seek while no stream was found yet\n");
  82         return AVERROR(EINVAL);
  83     }
  84
  85     st = s->streams[stream_index];
  86     sti = ffstream(st);
  87     index = av_index_search_timestamp(st, timestamp, flags);
  88
  89     if (index >= 0 && index < sti->nb_index_entries - 1) {
  90         const AVIndexEntry *const e = &sti->index_entries[index];
  91         avio_seek(s->pb, e->pos, SEEK_SET);
  92         voc->pts = e->timestamp;
  93         voc->remaining_size = e->size;
  94         return 0;
  95     } else if (sti->nb_index_entries && sti->index_entries[0].timestamp <= timestamp) {
  96         const AVIndexEntry *const e = &sti->index_entries[sti->nb_index_entries - 1];
  97         // prepare context for seek_frame_generic()
  98         voc->pts = e->timestamp;
  99         voc->remaining_size = e->size;
 100     }
 101     return -1;
 102 }
 103
 104 const FFInputFormat ff_voc_demuxer = {
 105     .p.name         = "voc",
 106     .p.long_name    = NULL_IF_CONFIG_SMALL("Creative Voice"),
 107     .p.codec_tag    = ff_voc_codec_tags_list,
 108     .priv_data_size = sizeof(VocDecContext),
 109     .read_probe     = voc_probe,
 110     .read_header    = voc_read_header,
 111     .read_packet    = voc_read_packet,
 112     .read_seek      = voc_read_seek,
 113 };