FFmpeg: libavformat/tmv.c Source File

FFmpeg
tmv.c
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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  * @file
24  * 8088flex TMV file demuxer
25  * @author Daniel Verkamp
26  * @see http://www.oldskool.org/pc/8088_Corruption
27  */
28 
29 #include "libavutil/channel_layout.h"
30 #include "libavutil/intreadwrite.h"
31 #include "avformat.h"
32 #include "internal.h"
33 
34 enum {
35   TMV_PADDING = 0x01,
36   TMV_STEREO = 0x02,
37 };
38 
39  #define TMV_TAG MKTAG('T', 'M', 'A', 'V')
40 
41  typedef struct TMVContext {
42   unsigned audio_chunk_size;
43   unsigned video_chunk_size;
44   unsigned padding;
45   unsigned stream_index;
46 } TMVContext;
47 
48  #define TMV_HEADER_SIZE 12
49 
50  #define PROBE_MIN_SAMPLE_RATE 5000
51  #define PROBE_MAX_FPS 120
52  #define PROBE_MIN_AUDIO_SIZE (PROBE_MIN_SAMPLE_RATE / PROBE_MAX_FPS)
53 
54  static int tmv_probe(AVProbeData *p)
55 {
56  if (AV_RL32(p->buf) == TMV_TAG &&
57  AV_RL16(p->buf+4) >= PROBE_MIN_SAMPLE_RATE &&
58  AV_RL16(p->buf+6) >= PROBE_MIN_AUDIO_SIZE &&
59  !p->buf[8] && // compression method
60  p->buf[9] && // char cols
61  p->buf[10]) // char rows
62  return AVPROBE_SCORE_MAX /
63  ((p->buf[9] == 40 && p->buf[10] == 25) ? 1 : 4);
64  return 0;
65 }
66 
67  static int tmv_read_header(AVFormatContext *s)
68 {
69  TMVContext *tmv = s->priv_data;
70  AVIOContext *pb = s->pb;
71  AVStream *vst, *ast;
72  AVRational fps;
73  unsigned comp_method, char_cols, char_rows, features;
74 
75  if (avio_rl32(pb) != TMV_TAG)
76  return -1;
77 
78  if (!(vst = avformat_new_stream(s, NULL)))
79  return AVERROR(ENOMEM);
80 
81  if (!(ast = avformat_new_stream(s, NULL)))
82  return AVERROR(ENOMEM);
83 
84  ast->codec->sample_rate = avio_rl16(pb);
85  if (!ast->codec->sample_rate) {
86  av_log(s, AV_LOG_ERROR, "invalid sample rate\n");
87  return -1;
88  }
89 
90  tmv->audio_chunk_size = avio_rl16(pb);
91  if (!tmv->audio_chunk_size) {
92  av_log(s, AV_LOG_ERROR, "invalid audio chunk size\n");
93  return -1;
94  }
95 
96  comp_method = avio_r8(pb);
97  if (comp_method) {
98  av_log(s, AV_LOG_ERROR, "unsupported compression method %d\n",
99  comp_method);
100  return -1;
101  }
102 
103  char_cols = avio_r8(pb);
104  char_rows = avio_r8(pb);
105  tmv->video_chunk_size = char_cols * char_rows * 2;
106 
107  features = avio_r8(pb);
108  if (features & ~(TMV_PADDING | TMV_STEREO)) {
109  av_log(s, AV_LOG_ERROR, "unsupported features 0x%02x\n",
110  features & ~(TMV_PADDING | TMV_STEREO));
111  return -1;
112  }
113 
114  ast->codec->codec_type = AVMEDIA_TYPE_AUDIO;
115  ast->codec->codec_id = AV_CODEC_ID_PCM_U8;
116  if (features & TMV_STEREO) {
117  ast->codec->channels = 2;
118  ast->codec->channel_layout = AV_CH_LAYOUT_STEREO;
119  } else {
120  ast->codec->channels = 1;
121  ast->codec->channel_layout = AV_CH_LAYOUT_MONO;
122  }
123  ast->codec->bits_per_coded_sample = 8;
124  ast->codec->bit_rate = ast->codec->sample_rate *
125  ast->codec->bits_per_coded_sample;
126  avpriv_set_pts_info(ast, 32, 1, ast->codec->sample_rate);
127 
128  fps.num = ast->codec->sample_rate * ast->codec->channels;
129  fps.den = tmv->audio_chunk_size;
130  av_reduce(&fps.num, &fps.den, fps.num, fps.den, 0xFFFFFFFFLL);
131 
132  vst->codec->codec_type = AVMEDIA_TYPE_VIDEO;
133  vst->codec->codec_id = AV_CODEC_ID_TMV;
134  vst->codec->pix_fmt = AV_PIX_FMT_PAL8;
135  vst->codec->width = char_cols * 8;
136  vst->codec->height = char_rows * 8;
137  avpriv_set_pts_info(vst, 32, fps.den, fps.num);
138 
139  if (features & TMV_PADDING)
140  tmv->padding =
141  ((tmv->video_chunk_size + tmv->audio_chunk_size + 511) & ~511) -
142  (tmv->video_chunk_size + tmv->audio_chunk_size);
143 
144  vst->codec->bit_rate = ((tmv->video_chunk_size + tmv->padding) *
145  fps.num * 8) / fps.den;
146 
147  return 0;
148 }
149 
150  static int tmv_read_packet(AVFormatContext *s, AVPacket *pkt)
151 {
152  TMVContext *tmv = s->priv_data;
153  AVIOContext *pb = s->pb;
154  int ret, pkt_size = tmv->stream_index ?
155  tmv->audio_chunk_size : tmv->video_chunk_size;
156 
157  if (avio_feof(pb))
158  return AVERROR_EOF;
159 
160  ret = av_get_packet(pb, pkt, pkt_size);
161 
162  if (tmv->stream_index)
163  avio_skip(pb, tmv->padding);
164 
165  pkt->stream_index = tmv->stream_index;
166  tmv->stream_index ^= 1;
167  pkt->flags |= AV_PKT_FLAG_KEY;
168 
169  return ret;
170 }
171 
172  static int tmv_read_seek(AVFormatContext *s, int stream_index,
173  int64_t timestamp, int flags)
174 {
175  TMVContext *tmv = s->priv_data;
176  int64_t pos;
177 
178  if (stream_index)
179  return -1;
180 
181  pos = timestamp *
182  (tmv->audio_chunk_size + tmv->video_chunk_size + tmv->padding);
183 
184  if (avio_seek(s->pb, pos + TMV_HEADER_SIZE, SEEK_SET) < 0)
185  return -1;
186  tmv->stream_index = 0;
187  return 0;
188 }
189 
190  AVInputFormat ff_tmv_demuxer = {
191  .name = "tmv",
192  .long_name = NULL_IF_CONFIG_SMALL("8088flex TMV"),
193  .priv_data_size = sizeof(TMVContext),
194  .read_probe = tmv_probe,
195  .read_header = tmv_read_header,
196  .read_packet = tmv_read_packet,
197  .read_seek = tmv_read_seek,
198  .flags = AVFMT_GENERIC_INDEX,
199 };
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