mtv.c
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1 /*
2  * mtv demuxer
3  * Copyright (c) 2006 Reynaldo H. Verdejo Pinochet
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 
27 #include "libavutil/bswap.h"
28 #include "libavutil/intreadwrite.h"
29 #include "avformat.h"
30 #include "internal.h"
31 
32 #define MTV_ASUBCHUNK_DATA_SIZE 500
33 #define MTV_HEADER_SIZE 512
34 #define MTV_AUDIO_PADDING_SIZE 12
35 #define AUDIO_SAMPLING_RATE 44100
36 
37 typedef struct MTVDemuxContext {
38 
39  unsigned int file_size;
40  unsigned int segments;
41  unsigned int audio_identifier;
42  unsigned int audio_br;
43  unsigned int img_colorfmt;
44  unsigned int img_bpp;
45  unsigned int img_width; //
46  unsigned int img_height; //
47  unsigned int img_segment_size;
48  unsigned int video_fps; //
49  unsigned int full_segment_size;
50 
52 
53 static int mtv_probe(AVProbeData *p)
54 {
55  /* Magic is 'AMV' */
56  if (*p->buf != 'A' || *(p->buf + 1) != 'M' || *(p->buf + 2) != 'V')
57  return 0;
58 
59  /* Check for nonzero in bpp and (width|height) header fields */
60  if(!(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54])))
61  return 0;
62 
63  /* If width or height are 0 then imagesize header field should not */
64  if(!AV_RL16(&p->buf[52]) || !AV_RL16(&p->buf[54]))
65  {
66  if(!!AV_RL16(&p->buf[56]))
67  return AVPROBE_SCORE_MAX/2;
68  else
69  return 0;
70  }
71 
72  if(p->buf[51] != 16)
73  return AVPROBE_SCORE_MAX/4; // But we are going to assume 16bpp anyway ..
74 
75  return AVPROBE_SCORE_MAX;
76 }
77 
79 {
80  MTVDemuxContext *mtv = s->priv_data;
81  AVIOContext *pb = s->pb;
82  AVStream *st;
83  unsigned int audio_subsegments;
84 
85  avio_skip(pb, 3);
86  mtv->file_size = avio_rl32(pb);
87  mtv->segments = avio_rl32(pb);
88  avio_skip(pb, 32);
89  mtv->audio_identifier = avio_rl24(pb);
90  mtv->audio_br = avio_rl16(pb);
91  mtv->img_colorfmt = avio_rl24(pb);
92  mtv->img_bpp = avio_r8(pb);
93  mtv->img_width = avio_rl16(pb);
94  mtv->img_height = avio_rl16(pb);
95  mtv->img_segment_size = avio_rl16(pb);
96 
97  /* Calculate width and height if missing from header */
98 
99  if(!mtv->img_width)
100  mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)
101  / mtv->img_height;
102 
103  if(!mtv->img_height)
104  mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)
105  / mtv->img_width;
106 
107  avio_skip(pb, 4);
108  audio_subsegments = avio_rl16(pb);
109 
110  if (audio_subsegments == 0) {
111  av_log_ask_for_sample(s, "MTV files without audio are not supported\n");
112  return AVERROR_INVALIDDATA;
113  }
114 
115  mtv->full_segment_size =
116  audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +
117  mtv->img_segment_size;
118  mtv->video_fps = (mtv->audio_br / 4) / audio_subsegments;
119 
120  // FIXME Add sanity check here
121 
122  // all systems go! init decoders
123 
124  // video - raw rgb565
125 
126  st = avformat_new_stream(s, NULL);
127  if(!st)
128  return AVERROR(ENOMEM);
129 
130  avpriv_set_pts_info(st, 64, 1, mtv->video_fps);
134  st->codec->width = mtv->img_width;
135  st->codec->height = mtv->img_height;
136  st->codec->sample_rate = mtv->video_fps;
137  st->codec->extradata = av_strdup("BottomUp");
138  st->codec->extradata_size = 9;
139 
140  // audio - mp3
141 
142  st = avformat_new_stream(s, NULL);
143  if(!st)
144  return AVERROR(ENOMEM);
145 
148  st->codec->codec_id = CODEC_ID_MP3;
149  st->codec->bit_rate = mtv->audio_br;
151 
152  // Jump over header
153 
154  if(avio_seek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)
155  return AVERROR(EIO);
156 
157  return 0;
158 
159 }
160 
162 {
163  MTVDemuxContext *mtv = s->priv_data;
164  AVIOContext *pb = s->pb;
165  int ret;
166 #if !HAVE_BIGENDIAN
167  int i;
168 #endif
169 
170  if((avio_tell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
171  {
173 
174  ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
175  if(ret < 0)
176  return ret;
177 
178  pkt->pos -= MTV_AUDIO_PADDING_SIZE;
179  pkt->stream_index = 1;
180 
181  }else
182  {
183  ret = av_get_packet(pb, pkt, mtv->img_segment_size);
184  if(ret < 0)
185  return ret;
186 
187 #if !HAVE_BIGENDIAN
188 
189  /* pkt->data is GGGRRRR BBBBBGGG
190  * and we need RRRRRGGG GGGBBBBB
191  * for PIX_FMT_RGB565 so here we
192  * just swap bytes as they come
193  */
194 
195  for(i=0;i<mtv->img_segment_size/2;i++)
196  *((uint16_t *)pkt->data+i) = av_bswap16(*((uint16_t *)pkt->data+i));
197 #endif
198  pkt->stream_index = 0;
199  }
200 
201  return ret;
202 }
203 
205  .name = "MTV",
206  .long_name = NULL_IF_CONFIG_SMALL("MTV format"),
207  .priv_data_size = sizeof(MTVDemuxContext),
211 };