1/*
2 * mtv demuxer
3 * Copyright (c) 2006 Reynaldo H. Verdejo Pinochet
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 libavformat/mtv.c
24 * MTV demuxer.
25 */
26
27#include "libavutil/bswap.h"
28#include "avformat.h"
29
30#define MTV_ASUBCHUNK_DATA_SIZE 500
31#define MTV_HEADER_SIZE 512
32#define MTV_AUDIO_PADDING_SIZE 12
33#define AUDIO_SAMPLING_RATE 44100
34#define VIDEO_SID 0
35#define AUDIO_SID 1
36
37typedef struct MTVDemuxContext {
38
39    unsigned int file_size;         ///< filesize, not always right
40    unsigned int segments;          ///< number of 512 byte segments
41    unsigned int audio_identifier;  ///< 'MP3' on all files I have seen
42    unsigned int audio_br;          ///< bitrate of audio chanel (mp3)
43    unsigned int img_colorfmt;      ///< frame colorfmt rgb 565/555
44    unsigned int img_bpp;           ///< frame bits per pixel
45    unsigned int img_width;         //
46    unsigned int img_height;        //
47    unsigned int img_segment_size;  ///< size of image segment
48    unsigned int video_fps;         //
49    unsigned int full_segment_size;
50
51} MTVDemuxContext;
52
53static 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    return AVPROBE_SCORE_MAX;
60}
61
62static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
63{
64    MTVDemuxContext *mtv = s->priv_data;
65    ByteIOContext   *pb  = s->pb;
66    AVStream        *st;
67    unsigned int    audio_subsegments;
68
69    url_fskip(pb, 3);
70    mtv->file_size         = get_le32(pb);
71    mtv->segments          = get_le32(pb);
72    url_fskip(pb, 32);
73    mtv->audio_identifier  = get_le24(pb);
74    mtv->audio_br          = get_le16(pb);
75    mtv->img_colorfmt      = get_le24(pb);
76    mtv->img_bpp           = get_byte(pb);
77    mtv->img_width         = get_le16(pb);
78    mtv->img_height        = get_le16(pb);
79    mtv->img_segment_size  = get_le16(pb);
80    url_fskip(pb, 4);
81    audio_subsegments = get_le16(pb);
82    mtv->full_segment_size =
83        audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +
84        mtv->img_segment_size;
85    mtv->video_fps         = (mtv->audio_br / 4) / audio_subsegments;
86
87    // FIXME Add sanity check here
88
89    // all systems go! init decoders
90
91    // video - raw rgb565
92
93    st = av_new_stream(s, VIDEO_SID);
94    if(!st)
95        return AVERROR(ENOMEM);
96
97    av_set_pts_info(st, 64, 1, mtv->video_fps);
98    st->codec->codec_type      = CODEC_TYPE_VIDEO;
99    st->codec->codec_id        = CODEC_ID_RAWVIDEO;
100    st->codec->codec_tag       = MKTAG('R', 'G', 'B', mtv->img_bpp);
101    st->codec->width           = mtv->img_width;
102    st->codec->height          = mtv->img_height;
103    st->codec->bits_per_coded_sample = mtv->img_bpp;
104    st->codec->sample_rate     = mtv->video_fps;
105
106    // audio - mp3
107
108    st = av_new_stream(s, AUDIO_SID);
109    if(!st)
110        return AVERROR(ENOMEM);
111
112    av_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);
113    st->codec->codec_type      = CODEC_TYPE_AUDIO;
114    st->codec->codec_id        = CODEC_ID_MP3;
115    st->codec->bit_rate        = mtv->audio_br;
116    st->need_parsing           = AVSTREAM_PARSE_FULL;
117
118    // Jump over header
119
120    if(url_fseek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)
121        return AVERROR(EIO);
122
123    return 0;
124
125}
126
127static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
128{
129    MTVDemuxContext *mtv = s->priv_data;
130    ByteIOContext *pb = s->pb;
131    int ret;
132#ifndef WORDS_BIGENDIAN
133    int i;
134#endif
135
136    ret = 0;
137
138    if((url_ftell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
139    {
140        url_fskip(pb, MTV_AUDIO_PADDING_SIZE);
141
142        ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
143        if(ret != MTV_ASUBCHUNK_DATA_SIZE)
144            return AVERROR(EIO);
145
146        pkt->pos -= MTV_AUDIO_PADDING_SIZE;
147        pkt->stream_index = AUDIO_SID;
148
149    }else
150    {
151        ret = av_get_packet(pb, pkt, mtv->img_segment_size);
152        if(ret != mtv->img_segment_size)
153            return AVERROR(EIO);
154
155#ifndef WORDS_BIGENDIAN
156
157        /* pkt->data is GGGRRRR BBBBBGGG
158         * and we need RRRRRGGG GGGBBBBB
159         * for PIX_FMT_RGB565 so here we
160         * just swap bytes as they come
161         */
162
163        for(i=0;i<mtv->img_segment_size/2;i++)
164            *((uint16_t *)pkt->data+i) = bswap_16(*((uint16_t *)pkt->data+i));
165#endif
166        pkt->stream_index = VIDEO_SID;
167    }
168
169    return ret;
170}
171
172AVInputFormat mtv_demuxer = {
173    "MTV",
174    NULL_IF_CONFIG_SMALL("MTV format"),
175    sizeof(MTVDemuxContext),
176    mtv_probe,
177    mtv_read_header,
178    mtv_read_packet,
179};
180