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 PROBE_MIN_SAMPLE_RATE 5000
47 #define PROBE_MAX_FPS 120
48 #define PROBE_MIN_AUDIO_SIZE (PROBE_MIN_SAMPLE_RATE / PROBE_MAX_FPS)
50 static int tmv_probe(AVProbeData *p)
52 if (AV_RL32(p->buf) == TMV_TAG &&
53 AV_RL16(p->buf+4) >= PROBE_MIN_SAMPLE_RATE &&
54 AV_RL16(p->buf+6) >= PROBE_MIN_AUDIO_SIZE &&
55 !p->buf[8] && // compression method
56 p->buf[9] && // char cols
57 p->buf[10]) // char rows
58 return AVPROBE_SCORE_MAX / (p->buf[9] == 40 && p->buf[10] == 25)? 1 : 4;
62 static int tmv_read_header(AVFormatContext *s, AVFormatParameters *ap)
64 TMVContext *tmv = s->priv_data;
65 ByteIOContext *pb = s->pb;
68 unsigned comp_method, char_cols, char_rows, features;
70 if (get_le32(pb) != TMV_TAG)
73 if (!(vst = av_new_stream(s, 0)))
74 return AVERROR(ENOMEM);
76 if (!(ast = av_new_stream(s, 0)))
77 return AVERROR(ENOMEM);
79 ast->codec->sample_rate = get_le16(pb);
80 if (!ast->codec->sample_rate) {
81 av_log(s, AV_LOG_ERROR, "invalid sample rate\n");
85 tmv->audio_chunk_size = get_le16(pb);
86 if (!tmv->audio_chunk_size) {
87 av_log(s, AV_LOG_ERROR, "invalid audio chunk size\n");
91 comp_method = get_byte(pb);
93 av_log(s, AV_LOG_ERROR, "unsupported compression method %d\n",
98 char_cols = get_byte(pb);
99 char_rows = get_byte(pb);
100 tmv->video_chunk_size = char_cols * char_rows * 2;
102 features = get_byte(pb);
103 if (features & ~(TMV_PADDING | TMV_STEREO)) {
104 av_log(s, AV_LOG_ERROR, "unsupported features 0x%02x\n",
105 features & ~(TMV_PADDING | TMV_STEREO));
109 ast->codec->codec_type = CODEC_TYPE_AUDIO;
110 ast->codec->codec_id = CODEC_ID_PCM_U8;
111 ast->codec->sample_fmt = SAMPLE_FMT_U8;
112 ast->codec->channels = features & TMV_STEREO ? 2 : 1;
113 ast->codec->bits_per_coded_sample = 8;
114 ast->codec->bit_rate = ast->codec->sample_rate *
115 ast->codec->bits_per_coded_sample;
116 av_set_pts_info(ast, 32, 1, ast->codec->sample_rate);
118 fps.num = ast->codec->sample_rate * ast->codec->channels;
119 fps.den = tmv->audio_chunk_size;
120 av_reduce(&fps.num, &fps.den, fps.num, fps.den, 0xFFFFFFFFLL);
122 vst->codec->codec_type = CODEC_TYPE_VIDEO;
123 vst->codec->codec_id = CODEC_ID_TMV;
124 vst->codec->pix_fmt = PIX_FMT_PAL8;
125 vst->codec->width = char_cols * 8;
126 vst->codec->height = char_rows * 8;
127 av_set_pts_info(vst, 32, fps.den, fps.num);
129 if (features & TMV_PADDING)
131 ((tmv->video_chunk_size + tmv->audio_chunk_size + 511) & ~511) -
132 (tmv->video_chunk_size + tmv->audio_chunk_size);
134 vst->codec->bit_rate = ((tmv->video_chunk_size + tmv->padding) *
135 fps.num * 8) / fps.den;
140 static int tmv_read_packet(AVFormatContext *s, AVPacket *pkt)
142 TMVContext *tmv = s->priv_data;
143 ByteIOContext *pb = s->pb;
144 int ret, pkt_size = tmv->stream_index ?
145 tmv->audio_chunk_size : tmv->video_chunk_size;
150 ret = av_get_packet(pb, pkt, pkt_size);
152 if (tmv->stream_index)
153 url_fskip(pb, tmv->padding);
155 pkt->stream_index = tmv->stream_index;
156 tmv->stream_index ^= 1;
157 pkt->flags |= PKT_FLAG_KEY;
162 AVInputFormat tmv_demuxer = {
164 NULL_IF_CONFIG_SMALL("8088flex TMV"),
169 .flags = AVFMT_GENERIC_INDEX,