2 * 8088flex TMV file demuxer
3 * Copyright (c) 2009 Daniel Verkamp <daniel at drv.nu>
5 * This file is part of FFmpeg.
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.
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.
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
23 * 8088flex TMV file demuxer
24 * @file libavformat/tmv.c
25 * @author Daniel Verkamp
26 * @sa http://www.oldskool.org/pc/8088_Corruption
29 #include "libavutil/intreadwrite.h"
37 #define TMV_TAG MKTAG('T', 'M', 'A', 'V')
39 typedef struct TMVContext {
40 unsigned audio_chunk_size;
41 unsigned video_chunk_size;
43 unsigned stream_index;
46 #define TMV_HEADER_SIZE 12
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)
52 static int tmv_probe(AVProbeData *p)
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);
65 static int tmv_read_header(AVFormatContext *s, AVFormatParameters *ap)
67 TMVContext *tmv = s->priv_data;
68 ByteIOContext *pb = s->pb;
71 unsigned comp_method, char_cols, char_rows, features;
73 if (get_le32(pb) != TMV_TAG)
76 if (!(vst = av_new_stream(s, 0)))
77 return AVERROR(ENOMEM);
79 if (!(ast = av_new_stream(s, 0)))
80 return AVERROR(ENOMEM);
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");
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");
94 comp_method = get_byte(pb);
96 av_log(s, AV_LOG_ERROR, "unsupported compression method %d\n",
101 char_cols = get_byte(pb);
102 char_rows = get_byte(pb);
103 tmv->video_chunk_size = char_cols * char_rows * 2;
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));
112 ast->codec->codec_type = CODEC_TYPE_AUDIO;
113 ast->codec->codec_id = CODEC_ID_PCM_U8;
114 ast->codec->sample_fmt = SAMPLE_FMT_U8;
115 ast->codec->channels = features & TMV_STEREO ? 2 : 1;
116 ast->codec->bits_per_coded_sample = 8;
117 ast->codec->bit_rate = ast->codec->sample_rate *
118 ast->codec->bits_per_coded_sample;
119 av_set_pts_info(ast, 32, 1, ast->codec->sample_rate);
121 fps.num = ast->codec->sample_rate * ast->codec->channels;
122 fps.den = tmv->audio_chunk_size;
123 av_reduce(&fps.num, &fps.den, fps.num, fps.den, 0xFFFFFFFFLL);
125 vst->codec->codec_type = CODEC_TYPE_VIDEO;
126 vst->codec->codec_id = CODEC_ID_TMV;
127 vst->codec->pix_fmt = PIX_FMT_PAL8;
128 vst->codec->width = char_cols * 8;
129 vst->codec->height = char_rows * 8;
130 av_set_pts_info(vst, 32, fps.den, fps.num);
132 if (features & TMV_PADDING)
134 ((tmv->video_chunk_size + tmv->audio_chunk_size + 511) & ~511) -
135 (tmv->video_chunk_size + tmv->audio_chunk_size);
137 vst->codec->bit_rate = ((tmv->video_chunk_size + tmv->padding) *
138 fps.num * 8) / fps.den;
143 static int tmv_read_packet(AVFormatContext *s, AVPacket *pkt)
145 TMVContext *tmv = s->priv_data;
146 ByteIOContext *pb = s->pb;
147 int ret, pkt_size = tmv->stream_index ?
148 tmv->audio_chunk_size : tmv->video_chunk_size;
153 ret = av_get_packet(pb, pkt, pkt_size);
155 if (tmv->stream_index)
156 url_fskip(pb, tmv->padding);
158 pkt->stream_index = tmv->stream_index;
159 tmv->stream_index ^= 1;
160 pkt->flags |= PKT_FLAG_KEY;
165 static int tmv_read_seek(AVFormatContext *s, int stream_index,
166 int64_t timestamp, int flags)
168 TMVContext *tmv = s->priv_data;
175 (tmv->audio_chunk_size + tmv->video_chunk_size + tmv->padding);
177 url_fseek(s->pb, pos + TMV_HEADER_SIZE, SEEK_SET);
178 tmv->stream_index = 0;
182 AVInputFormat tmv_demuxer = {
184 NULL_IF_CONFIG_SMALL("8088flex TMV"),
191 .flags = AVFMT_GENERIC_INDEX,