libavformat/tmv.c

   1 /*
   2  * 8088flex TMV file demuxer
   3  * Copyright (c) 2009 Daniel Verkamp <daniel at drv.nu>
   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  * 8088flex TMV file demuxer
  24  * @file libavformat/tmv.c
  25  * @author Daniel Verkamp
  26  * @sa http://www.oldskool.org/pc/8088_Corruption
  27  */
  28
  29 #include "libavutil/intreadwrite.h"
  30 #include "avformat.h"
  31
  32 enum {
  33     TMV_PADDING = 0x01,
  34     TMV_STEREO  = 0x02,
  35 };
  36
  37 #define TMV_TAG MKTAG('T', 'M', 'A', 'V')
  38
  39 typedef struct TMVContext {
  40     unsigned audio_chunk_size;
  41     unsigned video_chunk_size;
  42     unsigned padding;
  43     unsigned stream_index;
  44 } TMVContext;
  45
  46 #define TMV_HEADER_SIZE       12
  47
  48 #define PROBE_MIN_SAMPLE_RATE 5000
  49 #define PROBE_MAX_FPS         120
  50 #define PROBE_MIN_AUDIO_SIZE  (PROBE_MIN_SAMPLE_RATE / PROBE_MAX_FPS)
  51
  52 static int tmv_probe(AVProbeData *p)
  53 {
  54     if (AV_RL32(p->buf)   == TMV_TAG &&
  55         AV_RL16(p->buf+4) >= PROBE_MIN_SAMPLE_RATE &&
  56         AV_RL16(p->buf+6) >= PROBE_MIN_AUDIO_SIZE  &&
  57                !p->buf[8] && // compression method
  58                 p->buf[9] && // char cols
  59                 p->buf[10])  // char rows
  60         return AVPROBE_SCORE_MAX /
  61             ((p->buf[9] == 40 && p->buf[10] == 25) ? 1 : 4);
  62     return 0;
  63 }
  64
  65 static int tmv_read_header(AVFormatContext *s, AVFormatParameters *ap)
  66 {
  67     TMVContext *tmv   = s->priv_data;
  68     ByteIOContext *pb = s->pb;
  69     AVStream *vst, *ast;
  70     AVRational fps;
  71     unsigned comp_method, char_cols, char_rows, features;
  72
  73     if (get_le32(pb) != TMV_TAG)
  74         return -1;
  75
  76     if (!(vst = av_new_stream(s, 0)))
  77         return AVERROR(ENOMEM);
  78
  79     if (!(ast = av_new_stream(s, 0)))
  80         return AVERROR(ENOMEM);
  81
  82     ast->codec->sample_rate = get_le16(pb);
  83     if (!ast->codec->sample_rate) {
  84         av_log(s, AV_LOG_ERROR, "invalid sample rate\n");
  85         return -1;
  86     }
  87
  88     tmv->audio_chunk_size   = get_le16(pb);
  89     if (!tmv->audio_chunk_size) {
  90         av_log(s, AV_LOG_ERROR, "invalid audio chunk size\n");
  91         return -1;
  92     }
  93
  94     comp_method             = get_byte(pb);
  95     if (comp_method) {
  96         av_log(s, AV_LOG_ERROR, "unsupported compression method %d\n",
  97                comp_method);
  98         return -1;
  99     }
 100
 101     char_cols = get_byte(pb);
 102     char_rows = get_byte(pb);
 103     tmv->video_chunk_size = char_cols * char_rows * 2;
 104
 105     features  = get_byte(pb);
 106     if (features & ~(TMV_PADDING | TMV_STEREO)) {
 107         av_log(s, AV_LOG_ERROR, "unsupported features 0x%02x\n",
 108                features & ~(TMV_PADDING | TMV_STEREO));
 109         return -1;
 110     }
 111
 112     ast->codec->codec_type            = CODEC_TYPE_AUDIO;
 113     ast->codec->codec_id              = CODEC_ID_PCM_U8;
 114     ast->codec->channels              = features & TMV_STEREO ? 2 : 1;
 115     ast->codec->bits_per_coded_sample = 8;
 116     ast->codec->bit_rate              = ast->codec->sample_rate *
 117                                         ast->codec->bits_per_coded_sample;
 118     av_set_pts_info(ast, 32, 1, ast->codec->sample_rate);
 119
 120     fps.num = ast->codec->sample_rate * ast->codec->channels;
 121     fps.den = tmv->audio_chunk_size;
 122     av_reduce(&fps.num, &fps.den, fps.num, fps.den, 0xFFFFFFFFLL);
 123
 124     vst->codec->codec_type = CODEC_TYPE_VIDEO;
 125     vst->codec->codec_id   = CODEC_ID_TMV;
 126     vst->codec->pix_fmt    = PIX_FMT_PAL8;
 127     vst->codec->width      = char_cols * 8;
 128     vst->codec->height     = char_rows * 8;
 129     av_set_pts_info(vst, 32, fps.den, fps.num);
 130
 131     if (features & TMV_PADDING)
 132         tmv->padding =
 133             ((tmv->video_chunk_size + tmv->audio_chunk_size + 511) & ~511) -
 134              (tmv->video_chunk_size + tmv->audio_chunk_size);
 135
 136     vst->codec->bit_rate = ((tmv->video_chunk_size + tmv->padding) *
 137                             fps.num * 8) / fps.den;
 138
 139     return 0;
 140 }
 141
 142 static int tmv_read_packet(AVFormatContext *s, AVPacket *pkt)
 143 {
 144     TMVContext *tmv   = s->priv_data;
 145     ByteIOContext *pb = s->pb;
 146     int ret, pkt_size = tmv->stream_index ?
 147                         tmv->audio_chunk_size : tmv->video_chunk_size;
 148
 149     if (url_feof(pb))
 150         return AVERROR_EOF;
 151
 152     ret = av_get_packet(pb, pkt, pkt_size);
 153
 154     if (tmv->stream_index)
 155         url_fskip(pb, tmv->padding);
 156
 157     pkt->stream_index  = tmv->stream_index;
 158     tmv->stream_index ^= 1;
 159     pkt->flags        |= PKT_FLAG_KEY;
 160
 161     return ret;
 162 }
 163
 164 static int tmv_read_seek(AVFormatContext *s, int stream_index,
 165                          int64_t timestamp, int flags)
 166 {
 167     TMVContext *tmv = s->priv_data;
 168     int64_t pos;
 169
 170     if (stream_index)
 171         return -1;
 172
 173     pos = timestamp *
 174           (tmv->audio_chunk_size + tmv->video_chunk_size + tmv->padding);
 175
 176     url_fseek(s->pb, pos + TMV_HEADER_SIZE, SEEK_SET);
 177     tmv->stream_index = 0;
 178     return 0;
 179 }
 180
 181 AVInputFormat tmv_demuxer = {
 182     "tmv",
 183     NULL_IF_CONFIG_SMALL("8088flex TMV"),
 184     sizeof(TMVContext),
 185     tmv_probe,
 186     tmv_read_header,
 187     tmv_read_packet,
 188     NULL,
 189     tmv_read_seek,
 190     .flags = AVFMT_GENERIC_INDEX,
 191 };