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ffmpeg / libavformat / mtv.c @ 5eef7bcd

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/*
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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 FFmpeg.
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 *
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 * FFmpeg 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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 * FFmpeg 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 FFmpeg; 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 libavformat/mtv.c
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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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#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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#define VIDEO_SID 0
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#define AUDIO_SID 1
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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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    ByteIOContext   *pb  = s->pb;
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    AVStream        *st;
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    unsigned int    audio_subsegments;
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    url_fskip(pb, 3);
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    mtv->file_size         = get_le32(pb);
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    mtv->segments          = get_le32(pb);
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    url_fskip(pb, 32);
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    mtv->audio_identifier  = get_le24(pb);
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    mtv->audio_br          = get_le16(pb);
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    mtv->img_colorfmt      = get_le24(pb);
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    mtv->img_bpp           = get_byte(pb);
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    mtv->img_width         = get_le16(pb);
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    mtv->img_height        = get_le16(pb);
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    mtv->img_segment_size  = get_le16(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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    url_fskip(pb, 4);
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    audio_subsegments = get_le16(pb);
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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 = av_new_stream(s, VIDEO_SID);
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    if(!st)
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        return AVERROR(ENOMEM);
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    av_set_pts_info(st, 64, 1, mtv->video_fps);
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    st->codec->codec_type      = CODEC_TYPE_VIDEO;
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    st->codec->codec_id        = CODEC_ID_RAWVIDEO;
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    st->codec->codec_tag       = MKTAG('R', 'G', 'B', mtv->img_bpp);
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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->bits_per_coded_sample = mtv->img_bpp;
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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 = av_new_stream(s, AUDIO_SID);
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    if(!st)
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        return AVERROR(ENOMEM);
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    av_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);
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    st->codec->codec_type      = CODEC_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(url_fseek(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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    ByteIOContext *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((url_ftell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
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    {
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        url_fskip(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 = AUDIO_SID;
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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) = bswap_16(*((uint16_t *)pkt->data+i));
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#endif
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        pkt->stream_index = VIDEO_SID;
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    }
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    return ret;
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}
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AVInputFormat mtv_demuxer = {
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    "MTV",
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    NULL_IF_CONFIG_SMALL("MTV format"),
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    sizeof(MTVDemuxContext),
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    mtv_probe,
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    mtv_read_header,
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    mtv_read_packet,
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};