3 * Copyright (c) 2006 Reynaldo H. Verdejo Pinochet
5 * This file is part of Libav.
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.
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.
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
27 #include "libavutil/bswap.h"
28 #include "libavutil/intreadwrite.h"
31 #define MTV_ASUBCHUNK_DATA_SIZE 500
32 #define MTV_HEADER_SIZE 512
33 #define MTV_AUDIO_PADDING_SIZE 12
34 #define AUDIO_SAMPLING_RATE 44100
36 typedef struct MTVDemuxContext {
38 unsigned int file_size; ///< filesize, not always right
39 unsigned int segments; ///< number of 512 byte segments
40 unsigned int audio_identifier; ///< 'MP3' on all files I have seen
41 unsigned int audio_br; ///< bitrate of audio channel (mp3)
42 unsigned int img_colorfmt; ///< frame colorfmt rgb 565/555
43 unsigned int img_bpp; ///< frame bits per pixel
44 unsigned int img_width; //
45 unsigned int img_height; //
46 unsigned int img_segment_size; ///< size of image segment
47 unsigned int video_fps; //
48 unsigned int full_segment_size;
52 static int mtv_probe(AVProbeData *p)
55 if(*(p->buf) != 'A' || *(p->buf+1) != 'M' || *(p->buf+2) != 'V')
58 /* Check for nonzero in bpp and (width|height) header fields */
59 if(!(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54])))
62 /* If width or height are 0 then imagesize header field should not */
63 if(!AV_RL16(&p->buf[52]) || !AV_RL16(&p->buf[54]))
65 if(!!AV_RL16(&p->buf[56]))
66 return AVPROBE_SCORE_MAX/2;
72 return AVPROBE_SCORE_MAX/4; // But we are going to assume 16bpp anyway ..
74 return AVPROBE_SCORE_MAX;
77 static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
79 MTVDemuxContext *mtv = s->priv_data;
80 AVIOContext *pb = s->pb;
82 unsigned int audio_subsegments;
85 mtv->file_size = avio_rl32(pb);
86 mtv->segments = avio_rl32(pb);
88 mtv->audio_identifier = avio_rl24(pb);
89 mtv->audio_br = avio_rl16(pb);
90 mtv->img_colorfmt = avio_rl24(pb);
91 mtv->img_bpp = avio_r8(pb);
92 mtv->img_width = avio_rl16(pb);
93 mtv->img_height = avio_rl16(pb);
94 mtv->img_segment_size = avio_rl16(pb);
96 /* Calculate width and height if missing from header */
99 mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)
103 mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)
107 audio_subsegments = avio_rl16(pb);
108 mtv->full_segment_size =
109 audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +
110 mtv->img_segment_size;
111 mtv->video_fps = (mtv->audio_br / 4) / audio_subsegments;
113 // FIXME Add sanity check here
115 // all systems go! init decoders
117 // video - raw rgb565
119 st = avformat_new_stream(s, NULL);
121 return AVERROR(ENOMEM);
123 av_set_pts_info(st, 64, 1, mtv->video_fps);
124 st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
125 st->codec->codec_id = CODEC_ID_RAWVIDEO;
126 st->codec->pix_fmt = PIX_FMT_RGB565;
127 st->codec->width = mtv->img_width;
128 st->codec->height = mtv->img_height;
129 st->codec->sample_rate = mtv->video_fps;
130 st->codec->extradata = av_strdup("BottomUp");
131 st->codec->extradata_size = 9;
135 st = avformat_new_stream(s, NULL);
137 return AVERROR(ENOMEM);
139 av_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);
140 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
141 st->codec->codec_id = CODEC_ID_MP3;
142 st->codec->bit_rate = mtv->audio_br;
143 st->need_parsing = AVSTREAM_PARSE_FULL;
147 if(avio_seek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)
154 static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
156 MTVDemuxContext *mtv = s->priv_data;
157 AVIOContext *pb = s->pb;
163 if((avio_tell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
165 avio_skip(pb, MTV_AUDIO_PADDING_SIZE);
167 ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
171 pkt->pos -= MTV_AUDIO_PADDING_SIZE;
172 pkt->stream_index = 1;
176 ret = av_get_packet(pb, pkt, mtv->img_segment_size);
182 /* pkt->data is GGGRRRR BBBBBGGG
183 * and we need RRRRRGGG GGGBBBBB
184 * for PIX_FMT_RGB565 so here we
185 * just swap bytes as they come
188 for(i=0;i<mtv->img_segment_size/2;i++)
189 *((uint16_t *)pkt->data+i) = av_bswap16(*((uint16_t *)pkt->data+i));
191 pkt->stream_index = 0;
197 AVInputFormat ff_mtv_demuxer = {
199 .long_name = NULL_IF_CONFIG_SMALL("MTV format"),
200 .priv_data_size = sizeof(MTVDemuxContext),
201 .read_probe = mtv_probe,
202 .read_header = mtv_read_header,
203 .read_packet = mtv_read_packet,