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 24 * MTV demuxer. 25 */ 26 27#include "libavutil/bswap.h" 28#include "libavutil/intreadwrite.h" 29#include "avformat.h" 30 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 35#define VIDEO_SID 0 36#define AUDIO_SID 1 37 38typedef struct MTVDemuxContext { 39 40 unsigned int file_size; ///< filesize, not always right 41 unsigned int segments; ///< number of 512 byte segments 42 unsigned int audio_identifier; ///< 'MP3' on all files I have seen 43 unsigned int audio_br; ///< bitrate of audio channel (mp3) 44 unsigned int img_colorfmt; ///< frame colorfmt rgb 565/555 45 unsigned int img_bpp; ///< frame bits per pixel 46 unsigned int img_width; // 47 unsigned int img_height; // 48 unsigned int img_segment_size; ///< size of image segment 49 unsigned int video_fps; // 50 unsigned int full_segment_size; 51 52} MTVDemuxContext; 53 54static int mtv_probe(AVProbeData *p) 55{ 56 /* Magic is 'AMV' */ 57 if(*(p->buf) != 'A' || *(p->buf+1) != 'M' || *(p->buf+2) != 'V') 58 return 0; 59 60 /* Check for nonzero in bpp and (width|height) header fields */ 61 if(!(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54]))) 62 return 0; 63 64 /* If width or height are 0 then imagesize header field should not */ 65 if(!AV_RL16(&p->buf[52]) || !AV_RL16(&p->buf[54])) 66 { 67 if(!!AV_RL16(&p->buf[56])) 68 return AVPROBE_SCORE_MAX/2; 69 else 70 return 0; 71 } 72 73 if(p->buf[51] != 16) 74 return AVPROBE_SCORE_MAX/4; // But we are going to assume 16bpp anyway .. 75 76 return AVPROBE_SCORE_MAX; 77} 78 79static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap) 80{ 81 MTVDemuxContext *mtv = s->priv_data; 82 ByteIOContext *pb = s->pb; 83 AVStream *st; 84 unsigned int audio_subsegments; 85 86 url_fskip(pb, 3); 87 mtv->file_size = get_le32(pb); 88 mtv->segments = get_le32(pb); 89 url_fskip(pb, 32); 90 mtv->audio_identifier = get_le24(pb); 91 mtv->audio_br = get_le16(pb); 92 mtv->img_colorfmt = get_le24(pb); 93 mtv->img_bpp = get_byte(pb); 94 mtv->img_width = get_le16(pb); 95 mtv->img_height = get_le16(pb); 96 mtv->img_segment_size = get_le16(pb); 97 98 /* Calculate width and height if missing from header */ 99 100 if(!mtv->img_width) 101 mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3) 102 / mtv->img_height; 103 104 if(!mtv->img_height) 105 mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3) 106 / mtv->img_width; 107 108 url_fskip(pb, 4); 109 audio_subsegments = get_le16(pb); 110 mtv->full_segment_size = 111 audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) + 112 mtv->img_segment_size; 113 mtv->video_fps = (mtv->audio_br / 4) / audio_subsegments; 114 115 // FIXME Add sanity check here 116 117 // all systems go! init decoders 118 119 // video - raw rgb565 120 121 st = av_new_stream(s, VIDEO_SID); 122 if(!st) 123 return AVERROR(ENOMEM); 124 125 av_set_pts_info(st, 64, 1, mtv->video_fps); 126 st->codec->codec_type = AVMEDIA_TYPE_VIDEO; 127 st->codec->codec_id = CODEC_ID_RAWVIDEO; 128 st->codec->pix_fmt = PIX_FMT_RGB565; 129 st->codec->width = mtv->img_width; 130 st->codec->height = mtv->img_height; 131 st->codec->sample_rate = mtv->video_fps; 132 st->codec->extradata = av_strdup("BottomUp"); 133 st->codec->extradata_size = 9; 134 135 // audio - mp3 136 137 st = av_new_stream(s, AUDIO_SID); 138 if(!st) 139 return AVERROR(ENOMEM); 140 141 av_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE); 142 st->codec->codec_type = AVMEDIA_TYPE_AUDIO; 143 st->codec->codec_id = CODEC_ID_MP3; 144 st->codec->bit_rate = mtv->audio_br; 145 st->need_parsing = AVSTREAM_PARSE_FULL; 146 147 // Jump over header 148 149 if(url_fseek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE) 150 return AVERROR(EIO); 151 152 return 0; 153 154} 155 156static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt) 157{ 158 MTVDemuxContext *mtv = s->priv_data; 159 ByteIOContext *pb = s->pb; 160 int ret; 161#if !HAVE_BIGENDIAN 162 int i; 163#endif 164 165 if((url_ftell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size) 166 { 167 url_fskip(pb, MTV_AUDIO_PADDING_SIZE); 168 169 ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE); 170 if(ret < 0) 171 return ret; 172 173 pkt->pos -= MTV_AUDIO_PADDING_SIZE; 174 pkt->stream_index = AUDIO_SID; 175 176 }else 177 { 178 ret = av_get_packet(pb, pkt, mtv->img_segment_size); 179 if(ret < 0) 180 return ret; 181 182#if !HAVE_BIGENDIAN 183 184 /* pkt->data is GGGRRRR BBBBBGGG 185 * and we need RRRRRGGG GGGBBBBB 186 * for PIX_FMT_RGB565 so here we 187 * just swap bytes as they come 188 */ 189 190 for(i=0;i<mtv->img_segment_size/2;i++) 191 *((uint16_t *)pkt->data+i) = bswap_16(*((uint16_t *)pkt->data+i)); 192#endif 193 pkt->stream_index = VIDEO_SID; 194 } 195 196 return ret; 197} 198 199AVInputFormat mtv_demuxer = { 200 "MTV", 201 NULL_IF_CONFIG_SMALL("MTV format"), 202 sizeof(MTVDemuxContext), 203 mtv_probe, 204 mtv_read_header, 205 mtv_read_packet, 206}; 207