FFmpeg: libavformat/mtv.c Source File

00001 /*
00002  * mtv demuxer
00003  * Copyright (c) 2006 Reynaldo H. Verdejo Pinochet
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00027 #include "libavutil/bswap.h"
00028 #include "libavutil/intreadwrite.h"
00029 #include "avformat.h"
00030 #include "internal.h"
00031 
00032 #define MTV_ASUBCHUNK_DATA_SIZE 500
00033 #define MTV_HEADER_SIZE 512
00034 #define MTV_AUDIO_PADDING_SIZE 12
00035 #define AUDIO_SAMPLING_RATE 44100
00036 
00037 typedef struct MTVDemuxContext {
00038 
00039     unsigned int file_size;         
00040     unsigned int segments;          
00041     unsigned int audio_identifier;  
00042     unsigned int audio_br;          
00043     unsigned int img_colorfmt;      
00044     unsigned int img_bpp;           
00045     unsigned int img_width;         //
00046     unsigned int img_height;        //
00047     unsigned int img_segment_size;  
00048     unsigned int video_fps;         //
00049     unsigned int full_segment_size;
00050 
00051 } MTVDemuxContext;
00052 
00053 static int mtv_probe(AVProbeData *p)
00054 {
00055     /* Magic is 'AMV' */
00056     if (*p->buf != 'A' || *(p->buf + 1) != 'M' || *(p->buf + 2) != 'V')
00057         return 0;
00058 
00059     /* Check for nonzero in bpp and (width|height) header fields */
00060     if(!(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54])))
00061         return 0;
00062 
00063     /* If width or height are 0 then imagesize header field should not */
00064     if(!AV_RL16(&p->buf[52]) || !AV_RL16(&p->buf[54]))
00065     {
00066         if(!!AV_RL16(&p->buf[56]))
00067             return AVPROBE_SCORE_MAX/2;
00068         else
00069             return 0;
00070     }
00071 
00072     if(p->buf[51] != 16)
00073         return AVPROBE_SCORE_MAX/4; // But we are going to assume 16bpp anyway ..
00074 
00075     return AVPROBE_SCORE_MAX;
00076 }
00077 
00078 static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
00079 {
00080     MTVDemuxContext *mtv = s->priv_data;
00081     AVIOContext   *pb  = s->pb;
00082     AVStream        *st;
00083     unsigned int    audio_subsegments;
00084 
00085     avio_skip(pb, 3);
00086     mtv->file_size         = avio_rl32(pb);
00087     mtv->segments          = avio_rl32(pb);
00088     avio_skip(pb, 32);
00089     mtv->audio_identifier  = avio_rl24(pb);
00090     mtv->audio_br          = avio_rl16(pb);
00091     mtv->img_colorfmt      = avio_rl24(pb);
00092     mtv->img_bpp           = avio_r8(pb);
00093     mtv->img_width         = avio_rl16(pb);
00094     mtv->img_height        = avio_rl16(pb);
00095     mtv->img_segment_size  = avio_rl16(pb);
00096 
00097     /* Calculate width and height if missing from header */
00098 
00099     if(mtv->img_bpp>>3){
00100     if(!mtv->img_width && mtv->img_height)
00101         mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)
00102                         / mtv->img_height;
00103 
00104     if(!mtv->img_height && mtv->img_width)
00105         mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)
00106                         / mtv->img_width;
00107     }
00108     if(!mtv->img_height || !mtv->img_width){
00109         av_log(s, AV_LOG_ERROR, "width or height is invalid and I cannot calculate them from other information\n");
00110         return AVERROR(EINVAL);
00111     }
00112 
00113     avio_skip(pb, 4);
00114     audio_subsegments = avio_rl16(pb);
00115 
00116     if (audio_subsegments == 0) {
00117         av_log_ask_for_sample(s, "MTV files without audio are not supported\n");
00118         return AVERROR_INVALIDDATA;
00119     }
00120 
00121     mtv->full_segment_size =
00122         audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +
00123         mtv->img_segment_size;
00124     mtv->video_fps         = (mtv->audio_br / 4) / audio_subsegments;
00125 
00126     // FIXME Add sanity check here
00127 
00128     // all systems go! init decoders
00129 
00130     // video - raw rgb565
00131 
00132     st = avformat_new_stream(s, NULL);
00133     if(!st)
00134         return AVERROR(ENOMEM);
00135 
00136     avpriv_set_pts_info(st, 64, 1, mtv->video_fps);
00137     st->codec->codec_type      = AVMEDIA_TYPE_VIDEO;
00138     st->codec->codec_id        = CODEC_ID_RAWVIDEO;
00139     st->codec->pix_fmt         = PIX_FMT_RGB565;
00140     st->codec->width           = mtv->img_width;
00141     st->codec->height          = mtv->img_height;
00142     st->codec->sample_rate     = mtv->video_fps;
00143     st->codec->extradata       = av_strdup("BottomUp");
00144     st->codec->extradata_size  = 9;
00145 
00146     // audio - mp3
00147 
00148     st = avformat_new_stream(s, NULL);
00149     if(!st)
00150         return AVERROR(ENOMEM);
00151 
00152     avpriv_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);
00153     st->codec->codec_type      = AVMEDIA_TYPE_AUDIO;
00154     st->codec->codec_id        = CODEC_ID_MP3;
00155     st->codec->bit_rate        = mtv->audio_br;
00156     st->need_parsing           = AVSTREAM_PARSE_FULL;
00157 
00158     // Jump over header
00159 
00160     if(avio_seek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)
00161         return AVERROR(EIO);
00162 
00163     return 0;
00164 
00165 }
00166 
00167 static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
00168 {
00169     MTVDemuxContext *mtv = s->priv_data;
00170     AVIOContext *pb = s->pb;
00171     int ret;
00172 #if !HAVE_BIGENDIAN
00173     int i;
00174 #endif
00175 
00176     if((avio_tell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
00177     {
00178         avio_skip(pb, MTV_AUDIO_PADDING_SIZE);
00179 
00180         ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
00181         if(ret < 0)
00182             return ret;
00183 
00184         pkt->pos -= MTV_AUDIO_PADDING_SIZE;
00185         pkt->stream_index = 1;
00186 
00187     }else
00188     {
00189         ret = av_get_packet(pb, pkt, mtv->img_segment_size);
00190         if(ret < 0)
00191             return ret;
00192 
00193 #if !HAVE_BIGENDIAN
00194 
00195         /* pkt->data is GGGRRRR BBBBBGGG
00196          * and we need RRRRRGGG GGGBBBBB
00197          * for PIX_FMT_RGB565 so here we
00198          * just swap bytes as they come
00199          */
00200 
00201         for(i=0;i<ret/2;i++)
00202             *((uint16_t *)pkt->data+i) = av_bswap16(*((uint16_t *)pkt->data+i));
00203 #endif
00204         pkt->stream_index = 0;
00205     }
00206 
00207     return ret;
00208 }
00209 
00210 AVInputFormat ff_mtv_demuxer = {
00211     .name           = "MTV",
00212     .long_name      = NULL_IF_CONFIG_SMALL("MTV format"),
00213     .priv_data_size = sizeof(MTVDemuxContext),
00214     .read_probe     = mtv_probe,
00215     .read_header    = mtv_read_header,
00216     .read_packet    = mtv_read_packet,
00217 };