212 lines
6.2 KiB
C
212 lines
6.2 KiB
C
/*
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* mtv demuxer
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* Copyright (c) 2006 Reynaldo H. Verdejo Pinochet
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* MTV demuxer.
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*/
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#include "libavutil/bswap.h"
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#include "libavutil/intreadwrite.h"
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#include "avformat.h"
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#include "internal.h"
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#define MTV_ASUBCHUNK_DATA_SIZE 500
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#define MTV_HEADER_SIZE 512
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#define MTV_AUDIO_PADDING_SIZE 12
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#define AUDIO_SAMPLING_RATE 44100
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typedef struct MTVDemuxContext {
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unsigned int file_size; ///< filesize, not always right
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unsigned int segments; ///< number of 512 byte segments
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unsigned int audio_identifier; ///< 'MP3' on all files I have seen
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unsigned int audio_br; ///< bitrate of audio channel (mp3)
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unsigned int img_colorfmt; ///< frame colorfmt rgb 565/555
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unsigned int img_bpp; ///< frame bits per pixel
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unsigned int img_width; //
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unsigned int img_height; //
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unsigned int img_segment_size; ///< size of image segment
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unsigned int video_fps; //
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unsigned int full_segment_size;
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} MTVDemuxContext;
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static int mtv_probe(AVProbeData *p)
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{
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/* Magic is 'AMV' */
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if (*p->buf != 'A' || *(p->buf + 1) != 'M' || *(p->buf + 2) != 'V')
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return 0;
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/* Check for nonzero in bpp and (width|height) header fields */
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if(!(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54])))
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return 0;
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/* If width or height are 0 then imagesize header field should not */
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if(!AV_RL16(&p->buf[52]) || !AV_RL16(&p->buf[54]))
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{
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if(!!AV_RL16(&p->buf[56]))
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return AVPROBE_SCORE_MAX/2;
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else
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return 0;
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}
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if(p->buf[51] != 16)
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return AVPROBE_SCORE_MAX/4; // But we are going to assume 16bpp anyway ..
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return AVPROBE_SCORE_MAX;
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}
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static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
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{
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MTVDemuxContext *mtv = s->priv_data;
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AVIOContext *pb = s->pb;
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AVStream *st;
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unsigned int audio_subsegments;
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avio_skip(pb, 3);
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mtv->file_size = avio_rl32(pb);
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mtv->segments = avio_rl32(pb);
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avio_skip(pb, 32);
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mtv->audio_identifier = avio_rl24(pb);
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mtv->audio_br = avio_rl16(pb);
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mtv->img_colorfmt = avio_rl24(pb);
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mtv->img_bpp = avio_r8(pb);
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mtv->img_width = avio_rl16(pb);
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mtv->img_height = avio_rl16(pb);
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mtv->img_segment_size = avio_rl16(pb);
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/* Calculate width and height if missing from header */
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if(!mtv->img_width)
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mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)
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/ mtv->img_height;
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if(!mtv->img_height)
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mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)
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/ mtv->img_width;
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avio_skip(pb, 4);
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audio_subsegments = avio_rl16(pb);
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if (audio_subsegments == 0) {
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av_log_ask_for_sample(s, "MTV files without audio are not supported\n");
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return AVERROR_INVALIDDATA;
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}
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mtv->full_segment_size =
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audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +
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mtv->img_segment_size;
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mtv->video_fps = (mtv->audio_br / 4) / audio_subsegments;
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// FIXME Add sanity check here
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// all systems go! init decoders
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// video - raw rgb565
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st = avformat_new_stream(s, NULL);
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if(!st)
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return AVERROR(ENOMEM);
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avpriv_set_pts_info(st, 64, 1, mtv->video_fps);
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st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
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st->codec->codec_id = CODEC_ID_RAWVIDEO;
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st->codec->pix_fmt = PIX_FMT_RGB565;
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st->codec->width = mtv->img_width;
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st->codec->height = mtv->img_height;
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st->codec->sample_rate = mtv->video_fps;
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st->codec->extradata = av_strdup("BottomUp");
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st->codec->extradata_size = 9;
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// audio - mp3
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st = avformat_new_stream(s, NULL);
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if(!st)
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return AVERROR(ENOMEM);
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avpriv_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);
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st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
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st->codec->codec_id = CODEC_ID_MP3;
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st->codec->bit_rate = mtv->audio_br;
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st->need_parsing = AVSTREAM_PARSE_FULL;
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// Jump over header
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if(avio_seek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)
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return AVERROR(EIO);
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return 0;
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}
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static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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MTVDemuxContext *mtv = s->priv_data;
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AVIOContext *pb = s->pb;
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int ret;
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#if !HAVE_BIGENDIAN
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int i;
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#endif
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if((avio_tell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
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{
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avio_skip(pb, MTV_AUDIO_PADDING_SIZE);
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ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
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if(ret < 0)
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return ret;
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pkt->pos -= MTV_AUDIO_PADDING_SIZE;
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pkt->stream_index = 1;
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}else
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{
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ret = av_get_packet(pb, pkt, mtv->img_segment_size);
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if(ret < 0)
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return ret;
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#if !HAVE_BIGENDIAN
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/* pkt->data is GGGRRRR BBBBBGGG
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* and we need RRRRRGGG GGGBBBBB
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* for PIX_FMT_RGB565 so here we
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* just swap bytes as they come
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*/
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for(i=0;i<mtv->img_segment_size/2;i++)
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*((uint16_t *)pkt->data+i) = av_bswap16(*((uint16_t *)pkt->data+i));
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#endif
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pkt->stream_index = 0;
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}
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return ret;
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}
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AVInputFormat ff_mtv_demuxer = {
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.name = "MTV",
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.long_name = NULL_IF_CONFIG_SMALL("MTV format"),
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.priv_data_size = sizeof(MTVDemuxContext),
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.read_probe = mtv_probe,
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.read_header = mtv_read_header,
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.read_packet = mtv_read_packet,
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};
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