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/*

 * mtv demuxer

 * Copyright (c) 2006 Reynaldo H. Verdejo Pinochet

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * MTV demuxer.

 */

#include "libavutil/bswap.h"

#include "libavutil/intreadwrite.h"

#include "avformat.h"

#include "internal.h"

#define MTV_ASUBCHUNK_DATA_SIZE 500

#define MTV_HEADER_SIZE 512

#define MTV_AUDIO_PADDING_SIZE 12

#define MTV_IMAGE_DEFAULT_BPP 16

#define MTV_AUDIO_SAMPLING_RATE 44100

typedef struct MTVDemuxContext {

    unsigned int file_size;         ///< filesize, not always right

    unsigned int segments;          ///< number of 512 byte segments

    unsigned int audio_identifier;  ///< 'MP3' on all files I have seen

    unsigned int audio_br;          ///< bitrate of audio channel (mp3)

    unsigned int img_colorfmt;      ///< frame colorfmt rgb 565/555

    unsigned int img_bpp;           ///< frame bits per pixel

    unsigned int img_width;

    unsigned int img_height;

    unsigned int img_segment_size;  ///< size of image segment

    unsigned int video_fps;

    unsigned int full_segment_size;

} MTVDemuxContext;

static int mtv_probe(AVProbeData *p)

{

    /* we need at least 57 bytes from the header

     * to try parsing all required fields

     */

    if (p->buf_size < 57)

        return 0;

    /* Magic is 'AMV' */

    if (*p->buf != 'A' || *(p->buf + 1) != 'M' || *(p->buf + 2) != 'V')

        return 0;

    /* Audio magic is always MP3 */

    if (p->buf[43] != 'M' || p->buf[44] != 'P' || p->buf[45] != '3')

        return 0;

    /* Check for nonzero in bpp and (width|height) header fields */

    if(!(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54])))

        return 0;

    /* If width or height are 0 then imagesize header field should not */

    if(!AV_RL16(&p->buf[52]) || !AV_RL16(&p->buf[54]))

    {

        if(!!AV_RL16(&p->buf[56]))

            return AVPROBE_SCORE_EXTENSION;

        else

            return 0;

    }

    /* Image bpp is not an absolutely required

     * field as we latter claim it should be 16

     * no matter what. All samples in the wild

     * are RGB565/555.

     */

    if(p->buf[51] != MTV_IMAGE_DEFAULT_BPP)

        return AVPROBE_SCORE_EXTENSION / 2;

    /* We had enough data to parse header values

     * but we expect to be able to get 512 bytes

     * of header to be sure.

     */

    if (p->buf_size < MTV_HEADER_SIZE)

        return AVPROBE_SCORE_EXTENSION;

    return AVPROBE_SCORE_MAX;

}

static int mtv_read_header(AVFormatContext *s)

{

    MTVDemuxContext *mtv = s->priv_data;

    AVIOContext   *pb  = s->pb;

    AVStream        *st;

    unsigned int    audio_subsegments;

    avio_skip(pb, 3);

    mtv->file_size         = avio_rl32(pb);

    mtv->segments          = avio_rl32(pb);

    avio_skip(pb, 32);

    mtv->audio_identifier  = avio_rl24(pb);

    mtv->audio_br          = avio_rl16(pb);

    mtv->img_colorfmt      = avio_rl24(pb);

    mtv->img_bpp           = avio_r8(pb);

    mtv->img_width         = avio_rl16(pb);

    mtv->img_height        = avio_rl16(pb);

    mtv->img_segment_size  = avio_rl16(pb);

    /* Assume 16bpp even if claimed otherwise.

     * We know its going to be RGBG565/555 anyway

     */

    if (mtv->img_bpp != MTV_IMAGE_DEFAULT_BPP) {

        av_log (s, AV_LOG_WARNING, "Header claims %dbpp (!= 16). Ignoring\n",

                mtv->img_bpp);

        mtv->img_bpp = MTV_IMAGE_DEFAULT_BPP;

    }

    /* Calculate width and height if missing from header */

    if (!mtv->img_width && mtv->img_height > 0 && mtv->img_bpp >= 8)

        mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)

                        / mtv->img_height;

    if (!mtv->img_height && mtv->img_width > 0 && mtv->img_bpp >= 8)

        mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)

                        / mtv->img_width;

    if(!mtv->img_height || !mtv->img_width || !mtv->img_segment_size){

        av_log(s, AV_LOG_ERROR, "width or height or segment_size is invalid and I cannot calculate them from other information\n");

        return AVERROR_INVALIDDATA;

    }

    avio_skip(pb, 4);

    audio_subsegments = avio_rl16(pb);

    if (audio_subsegments == 0) {

        avpriv_request_sample(s, "MTV files without audio");

        return AVERROR_PATCHWELCOME;

    }

    mtv->full_segment_size =

        audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +

        mtv->img_segment_size;

    mtv->video_fps         = (mtv->audio_br / 4) / audio_subsegments;

    // FIXME Add sanity check here

    // all systems go! init decoders

    // video - raw rgb565

    st = avformat_new_stream(s, NULL);

    if(!st)

        return AVERROR(ENOMEM);

    avpriv_set_pts_info(st, 64, 1, mtv->video_fps);

    st->codec->codec_type      = AVMEDIA_TYPE_VIDEO;

    st->codec->codec_id        = AV_CODEC_ID_RAWVIDEO;

    st->codec->pix_fmt         = AV_PIX_FMT_RGB565BE;

    st->codec->width           = mtv->img_width;

    st->codec->height          = mtv->img_height;

    st->codec->extradata       = av_strdup("BottomUp");

    st->codec->extradata_size  = 9;

    // audio - mp3

    st = avformat_new_stream(s, NULL);

    if(!st)

        return AVERROR(ENOMEM);

    avpriv_set_pts_info(st, 64, 1, MTV_AUDIO_SAMPLING_RATE);

    st->codec->codec_type      = AVMEDIA_TYPE_AUDIO;

    st->codec->codec_id        = AV_CODEC_ID_MP3;

    st->codec->bit_rate        = mtv->audio_br;

    st->need_parsing           = AVSTREAM_PARSE_FULL;

    // Jump over header

    if(avio_seek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)

        return AVERROR(EIO);

    return 0;

}

static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)

{

    MTVDemuxContext *mtv = s->priv_data;

    AVIOContext *pb = s->pb;

    int ret;

    if((avio_tell(pb) - s->internal->data_offset + mtv->img_segment_size) % mtv->full_segment_size)

    {

        avio_skip(pb, MTV_AUDIO_PADDING_SIZE);

        ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);

        if(ret < 0)

            return ret;

        pkt->pos -= MTV_AUDIO_PADDING_SIZE;

        pkt->stream_index = 1;

    }else

    {

        ret = av_get_packet(pb, pkt, mtv->img_segment_size);

        if(ret < 0)

            return ret;

        pkt->stream_index = 0;

    }

    return ret;

}

AVInputFormat ff_mtv_demuxer = {

    .name           = "mtv",

    .long_name      = NULL_IF_CONFIG_SMALL("MTV"),

    .priv_data_size = sizeof(MTVDemuxContext),

    .read_probe     = mtv_probe,

    .read_header    = mtv_read_header,

    .read_packet    = mtv_read_packet,

};