thp.c

mediastreamer2是开源的网络传输媒体流的库

/*
 * THP Demuxer
 * Copyright (c) 2007 Marco Gerards.
 *
 * 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
 */


#include "avformat.h"

typedef struct ThpDemuxContext {
    int              version;
    int              first_frame;
    int              first_framesz;
    int              last_frame;
    int              compoff;
    int              framecnt;
    AVRational       fps;
    int              frame;
    int              next_frame;
    int              next_framesz;
    int              video_stream_index;
    int              audio_stream_index;
    int              compcount;
    unsigned char    components[16];
    AVStream*        vst;
    int              has_audio;
    int              audiosize;
} ThpDemuxContext;


static int thp_probe(AVProbeData *p)
{
    /* check file header */
    if (AV_RL32(p->buf) == MKTAG('T', 'H', 'P', '\0'))
        return AVPROBE_SCORE_MAX;
    else
        return 0;
}

static int thp_read_header(AVFormatContext *s,
                           AVFormatParameters *ap)
{
    ThpDemuxContext *thp = s->priv_data;
    AVStream *st;
    ByteIOContext *pb = s->pb;
    int i;

    /* Read the file header.  */
                           get_be32(pb); /* Skip Magic.  */
    thp->version         = get_be32(pb);

                           get_be32(pb); /* Max buf size.  */
                           get_be32(pb); /* Max samples.  */

    thp->fps             = av_d2q(av_int2flt(get_be32(pb)), INT_MAX);
    thp->framecnt        = get_be32(pb);
    thp->first_framesz   = get_be32(pb);
                           get_be32(pb); /* Data size.  */

    thp->compoff         = get_be32(pb);
                           get_be32(pb); /* offsetDataOffset.  */
    thp->first_frame     = get_be32(pb);
    thp->last_frame      = get_be32(pb);

    thp->next_framesz    = thp->first_framesz;
    thp->next_frame      = thp->first_frame;

    /* Read the component structure.  */
    url_fseek (pb, thp->compoff, SEEK_SET);
    thp->compcount       = get_be32(pb);

    /* Read the list of component types.  */
    get_buffer(pb, thp->components, 16);

    for (i = 0; i < thp->compcount; i++) {
        if (thp->components[i] == 0) {
            if (thp->vst != 0)
                break;

            /* Video component.  */
            st = av_new_stream(s, 0);
            if (!st)
                return AVERROR(ENOMEM);

            /* The denominator and numerator are switched because 1/fps
               is required.  */
            av_set_pts_info(st, 64, thp->fps.den, thp->fps.num);
            st->codec->codec_type = CODEC_TYPE_VIDEO;
            st->codec->codec_id = CODEC_ID_THP;
            st->codec->codec_tag = 0;  /* no fourcc */
            st->codec->width = get_be32(pb);
            st->codec->height = get_be32(pb);
            st->codec->sample_rate = av_q2d(thp->fps);
            thp->vst = st;
            thp->video_stream_index = st->index;

            if (thp->version == 0x11000)
                get_be32(pb); /* Unknown.  */
        } else if (thp->components[i] == 1) {
            if (thp->has_audio != 0)
                break;

            /* Audio component.  */
            st = av_new_stream(s, 0);
            if (!st)
                return AVERROR(ENOMEM);

            st->codec->codec_type = CODEC_TYPE_AUDIO;
            st->codec->codec_id = CODEC_ID_ADPCM_THP;
            st->codec->codec_tag = 0;  /* no fourcc */
            st->codec->channels    = get_be32(pb); /* numChannels.  */
            st->codec->sample_rate = get_be32(pb); /* Frequency.  */

            av_set_pts_info(st, 64, 1, st->codec->sample_rate);

            thp->audio_stream_index = st->index;
            thp->has_audio = 1;
        }
    }

    return 0;
}

static int thp_read_packet(AVFormatContext *s,
                            AVPacket *pkt)
{
    ThpDemuxContext *thp = s->priv_data;
    ByteIOContext *pb = s->pb;
    int size;
    int ret;

    if (thp->audiosize == 0) {
        /* Terminate when last frame is reached.  */
        if (thp->frame >= thp->framecnt)
            return AVERROR(EIO);

        url_fseek(pb, thp->next_frame, SEEK_SET);

        /* Locate the next frame and read out its size.  */
        thp->next_frame += thp->next_framesz;
        thp->next_framesz = get_be32(pb);

                        get_be32(pb); /* Previous total size.  */
        size          = get_be32(pb); /* Total size of this frame.  */

        /* Store the audiosize so the next time this function is called,
           the audio can be read.  */
        if (thp->has_audio)
            thp->audiosize = get_be32(pb); /* Audio size.  */
        else
            thp->frame++;

        ret = av_get_packet(pb, pkt, size);
        if (ret != size) {
            av_free_packet(pkt);
            return AVERROR(EIO);
        }

        pkt->stream_index = thp->video_stream_index;
    } else {
        ret = av_get_packet(pb, pkt, thp->audiosize);
        if (ret != thp->audiosize) {
            av_free_packet(pkt);
            return AVERROR(EIO);
        }

        pkt->stream_index = thp->audio_stream_index;
        thp->audiosize = 0;
        thp->frame++;
    }

    return 0;
}

AVInputFormat thp_demuxer = {
    "thp",
    "THP",
    sizeof(ThpDemuxContext),
    thp_probe,
    thp_read_header,
    thp_read_packet
};