tmv.c
Go to the documentation of this file.
1 /*
2  * 8088flex TMV file demuxer
3  * Copyright (c) 2009 Daniel Verkamp <daniel at drv.nu>
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
29 #include "libavutil/intreadwrite.h"
30 #include "avformat.h"
31 #include "internal.h"
32 
33 enum {
34  TMV_PADDING = 0x01,
35  TMV_STEREO = 0x02,
36 };
37 
38 #define TMV_TAG MKTAG('T', 'M', 'A', 'V')
39 
40 typedef struct TMVContext {
41  unsigned audio_chunk_size;
42  unsigned video_chunk_size;
43  unsigned padding;
44  unsigned stream_index;
45 } TMVContext;
46 
47 #define TMV_HEADER_SIZE 12
48 
49 #define PROBE_MIN_SAMPLE_RATE 5000
50 #define PROBE_MAX_FPS 120
51 #define PROBE_MIN_AUDIO_SIZE (PROBE_MIN_SAMPLE_RATE / PROBE_MAX_FPS)
52 
53 static int tmv_probe(AVProbeData *p)
54 {
55  if (AV_RL32(p->buf) == TMV_TAG &&
57  AV_RL16(p->buf+6) >= PROBE_MIN_AUDIO_SIZE &&
58  !p->buf[8] && // compression method
59  p->buf[9] && // char cols
60  p->buf[10]) // char rows
61  return AVPROBE_SCORE_MAX /
62  ((p->buf[9] == 40 && p->buf[10] == 25) ? 1 : 4);
63  return 0;
64 }
65 
67 {
68  TMVContext *tmv = s->priv_data;
69  AVIOContext *pb = s->pb;
70  AVStream *vst, *ast;
71  AVRational fps;
72  unsigned comp_method, char_cols, char_rows, features;
73 
74  if (avio_rl32(pb) != TMV_TAG)
75  return -1;
76 
77  if (!(vst = avformat_new_stream(s, NULL)))
78  return AVERROR(ENOMEM);
79 
80  if (!(ast = avformat_new_stream(s, NULL)))
81  return AVERROR(ENOMEM);
82 
83  ast->codec->sample_rate = avio_rl16(pb);
84  if (!ast->codec->sample_rate) {
85  av_log(s, AV_LOG_ERROR, "invalid sample rate\n");
86  return -1;
87  }
88 
89  tmv->audio_chunk_size = avio_rl16(pb);
90  if (!tmv->audio_chunk_size) {
91  av_log(s, AV_LOG_ERROR, "invalid audio chunk size\n");
92  return -1;
93  }
94 
95  comp_method = avio_r8(pb);
96  if (comp_method) {
97  av_log(s, AV_LOG_ERROR, "unsupported compression method %d\n",
98  comp_method);
99  return -1;
100  }
101 
102  char_cols = avio_r8(pb);
103  char_rows = avio_r8(pb);
104  tmv->video_chunk_size = char_cols * char_rows * 2;
105 
106  features = avio_r8(pb);
107  if (features & ~(TMV_PADDING | TMV_STEREO)) {
108  av_log(s, AV_LOG_ERROR, "unsupported features 0x%02x\n",
109  features & ~(TMV_PADDING | TMV_STEREO));
110  return -1;
111  }
112 
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 *
119  avpriv_set_pts_info(ast, 32, 1, ast->codec->sample_rate);
120 
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);
124 
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  avpriv_set_pts_info(vst, 32, fps.den, fps.num);
131 
132  if (features & TMV_PADDING)
133  tmv->padding =
134  ((tmv->video_chunk_size + tmv->audio_chunk_size + 511) & ~511) -
135  (tmv->video_chunk_size + tmv->audio_chunk_size);
136 
137  vst->codec->bit_rate = ((tmv->video_chunk_size + tmv->padding) *
138  fps.num * 8) / fps.den;
139 
140  return 0;
141 }
142 
144 {
145  TMVContext *tmv = s->priv_data;
146  AVIOContext *pb = s->pb;
147  int ret, pkt_size = tmv->stream_index ?
149 
150  if (pb->eof_reached)
151  return AVERROR_EOF;
152 
153  ret = av_get_packet(pb, pkt, pkt_size);
154 
155  if (tmv->stream_index)
156  avio_skip(pb, tmv->padding);
157 
158  pkt->stream_index = tmv->stream_index;
159  tmv->stream_index ^= 1;
160  pkt->flags |= AV_PKT_FLAG_KEY;
161 
162  return ret;
163 }
164 
165 static int tmv_read_seek(AVFormatContext *s, int stream_index,
166  int64_t timestamp, int flags)
167 {
168  TMVContext *tmv = s->priv_data;
169  int64_t pos;
170 
171  if (stream_index)
172  return -1;
173 
174  pos = timestamp *
175  (tmv->audio_chunk_size + tmv->video_chunk_size + tmv->padding);
176 
177  avio_seek(s->pb, pos + TMV_HEADER_SIZE, SEEK_SET);
178  tmv->stream_index = 0;
179  return 0;
180 }
181 
183  .name = "tmv",
184  .long_name = NULL_IF_CONFIG_SMALL("8088flex TMV"),
185  .priv_data_size = sizeof(TMVContext),
191 };