ape.c.svn-base

mediastreamer2是开源的网络传输媒体流的库

    av_log(NULL, AV_LOG_DEBUG, "\nCalculated information:\n\n");
    av_log(NULL, AV_LOG_DEBUG, "junklength           = %d\n", ape_ctx->junklength);
    av_log(NULL, AV_LOG_DEBUG, "firstframe           = %d\n", ape_ctx->firstframe);
    av_log(NULL, AV_LOG_DEBUG, "totalsamples         = %d\n", ape_ctx->totalsamples);
#endif
}

static int ape_read_header(AVFormatContext * s, AVFormatParameters * ap)
{
    ByteIOContext *pb = s->pb;
    APEContext *ape = s->priv_data;
    AVStream *st;
    uint32_t tag;
    int i;
    int total_blocks;
    int64_t pts;

    /* TODO: Skip any leading junk such as id3v2 tags */
    ape->junklength = 0;

    tag = get_le32(pb);
    if (tag != MKTAG('M', 'A', 'C', ' '))
        return -1;

    ape->fileversion = get_le16(pb);

    if (ape->fileversion < APE_MIN_VERSION || ape->fileversion > APE_MAX_VERSION) {
        av_log(s, AV_LOG_ERROR, "Unsupported file version - %d.%02d\n", ape->fileversion / 1000, (ape->fileversion % 1000) / 10);
        return -1;
    }

    if (ape->fileversion >= 3980) {
        ape->padding1             = get_le16(pb);
        ape->descriptorlength     = get_le32(pb);
        ape->headerlength         = get_le32(pb);
        ape->seektablelength      = get_le32(pb);
        ape->wavheaderlength      = get_le32(pb);
        ape->audiodatalength      = get_le32(pb);
        ape->audiodatalength_high = get_le32(pb);
        ape->wavtaillength        = get_le32(pb);
        get_buffer(pb, ape->md5, 16);

        /* Skip any unknown bytes at the end of the descriptor.
           This is for future compatibility */
        if (ape->descriptorlength > 52)
            url_fseek(pb, ape->descriptorlength - 52, SEEK_CUR);

        /* Read header data */
        ape->compressiontype      = get_le16(pb);
        ape->formatflags          = get_le16(pb);
        ape->blocksperframe       = get_le32(pb);
        ape->finalframeblocks     = get_le32(pb);
        ape->totalframes          = get_le32(pb);
        ape->bps                  = get_le16(pb);
        ape->channels             = get_le16(pb);
        ape->samplerate           = get_le32(pb);
    } else {
        ape->descriptorlength = 0;
        ape->headerlength = 32;

        ape->compressiontype      = get_le16(pb);
        ape->formatflags          = get_le16(pb);
        ape->channels             = get_le16(pb);
        ape->samplerate           = get_le32(pb);
        ape->wavheaderlength      = get_le32(pb);
        ape->wavtaillength        = get_le32(pb);
        ape->totalframes          = get_le32(pb);
        ape->finalframeblocks     = get_le32(pb);

        if (ape->formatflags & MAC_FORMAT_FLAG_HAS_PEAK_LEVEL) {
            url_fseek(pb, 4, SEEK_CUR); /* Skip the peak level */
            ape->headerlength += 4;
        }

        if (ape->formatflags & MAC_FORMAT_FLAG_HAS_SEEK_ELEMENTS) {
            ape->seektablelength = get_le32(pb);
            ape->headerlength += 4;
            ape->seektablelength *= sizeof(int32_t);
        } else
            ape->seektablelength = ape->totalframes * sizeof(int32_t);

        if (ape->formatflags & MAC_FORMAT_FLAG_8_BIT)
            ape->bps = 8;
        else if (ape->formatflags & MAC_FORMAT_FLAG_24_BIT)
            ape->bps = 24;
        else
            ape->bps = 16;

        if (ape->fileversion >= 3950)
            ape->blocksperframe = 73728 * 4;
        else if (ape->fileversion >= 3900 || (ape->fileversion >= 3800  && ape->compressiontype >= 4000))
            ape->blocksperframe = 73728;
        else
            ape->blocksperframe = 9216;

        /* Skip any stored wav header */
        if (!(ape->formatflags & MAC_FORMAT_FLAG_CREATE_WAV_HEADER))
            url_fskip(pb, ape->wavheaderlength);
    }

    if(ape->totalframes > UINT_MAX / sizeof(APEFrame)){
        av_log(s, AV_LOG_ERROR, "Too many frames: %d\n", ape->totalframes);
        return -1;
    }
    ape->frames       = av_malloc(ape->totalframes * sizeof(APEFrame));
    if(!ape->frames)
        return AVERROR_NOMEM;
    ape->firstframe   = ape->junklength + ape->descriptorlength + ape->headerlength + ape->seektablelength + ape->wavheaderlength;
    ape->currentframe = 0;


    ape->totalsamples = ape->finalframeblocks;
    if (ape->totalframes > 1)
        ape->totalsamples += ape->blocksperframe * (ape->totalframes - 1);

    if (ape->seektablelength > 0) {
        ape->seektable = av_malloc(ape->seektablelength);
        for (i = 0; i < ape->seektablelength / sizeof(uint32_t); i++)
            ape->seektable[i] = get_le32(pb);
    }

    ape->frames[0].pos     = ape->firstframe;
    ape->frames[0].nblocks = ape->blocksperframe;
    ape->frames[0].skip    = 0;
    for (i = 1; i < ape->totalframes; i++) {
        ape->frames[i].pos      = ape->seektable[i]; //ape->frames[i-1].pos + ape->blocksperframe;
        ape->frames[i].nblocks  = ape->blocksperframe;
        ape->frames[i - 1].size = ape->frames[i].pos - ape->frames[i - 1].pos;
        ape->frames[i].skip     = (ape->frames[i].pos - ape->frames[0].pos) & 3;
    }
    ape->frames[ape->totalframes - 1].size    = ape->finalframeblocks * 4;
    ape->frames[ape->totalframes - 1].nblocks = ape->finalframeblocks;

    for (i = 0; i < ape->totalframes; i++) {
        if(ape->frames[i].skip){
            ape->frames[i].pos  -= ape->frames[i].skip;
            ape->frames[i].size += ape->frames[i].skip;
        }
        ape->frames[i].size = (ape->frames[i].size + 3) & ~3;
    }


    ape_dumpinfo(ape);

    /* try to read APE tags */
    if (!url_is_streamed(pb)) {
        ape_parse_tag(s);
        url_fseek(pb, 0, SEEK_SET);
    }

    av_log(s, AV_LOG_DEBUG, "Decoding file - v%d.%02d, compression level %d\n", ape->fileversion / 1000, (ape->fileversion % 1000) / 10, ape->compressiontype);

    /* now we are ready: build format streams */
    st = av_new_stream(s, 0);
    if (!st)
        return -1;

    total_blocks = (ape->totalframes == 0) ? 0 : ((ape->totalframes - 1) * ape->blocksperframe) + ape->finalframeblocks;

    st->codec->codec_type      = CODEC_TYPE_AUDIO;
    st->codec->codec_id        = CODEC_ID_APE;
    st->codec->codec_tag       = MKTAG('A', 'P', 'E', ' ');
    st->codec->channels        = ape->channels;
    st->codec->sample_rate     = ape->samplerate;
    st->codec->bits_per_sample = ape->bps;
    st->codec->frame_size      = MAC_SUBFRAME_SIZE;

    st->nb_frames = ape->totalframes;
    s->start_time = 0;
    s->duration   = (int64_t) total_blocks * AV_TIME_BASE / ape->samplerate;
    av_set_pts_info(st, 64, MAC_SUBFRAME_SIZE, ape->samplerate);

    st->codec->extradata = av_malloc(APE_EXTRADATA_SIZE);
    st->codec->extradata_size = APE_EXTRADATA_SIZE;
    AV_WL16(st->codec->extradata + 0, ape->fileversion);
    AV_WL16(st->codec->extradata + 2, ape->compressiontype);
    AV_WL16(st->codec->extradata + 4, ape->formatflags);

    pts = 0;
    for (i = 0; i < ape->totalframes; i++) {
        ape->frames[i].pts = pts;
        av_add_index_entry(st, ape->frames[i].pos, ape->frames[i].pts, 0, 0, AVINDEX_KEYFRAME);
        pts += ape->blocksperframe / MAC_SUBFRAME_SIZE;
    }

    return 0;
}

static int ape_read_packet(AVFormatContext * s, AVPacket * pkt)
{
    int ret;
    int nblocks;
    APEContext *ape = s->priv_data;
    uint32_t extra_size = 8;

    if (url_feof(s->pb))
        return AVERROR_IO;
    if (ape->currentframe > ape->totalframes)
        return AVERROR_IO;

    url_fseek (s->pb, ape->frames[ape->currentframe].pos, SEEK_SET);

    /* Calculate how many blocks there are in this frame */
    if (ape->currentframe == (ape->totalframes - 1))
        nblocks = ape->finalframeblocks;
    else
        nblocks = ape->blocksperframe;

    if (av_new_packet(pkt,  ape->frames[ape->currentframe].size + extra_size) < 0)
        return AVERROR_NOMEM;

    AV_WL32(pkt->data    , nblocks);
    AV_WL32(pkt->data + 4, ape->frames[ape->currentframe].skip);
    ret = get_buffer(s->pb, pkt->data + extra_size, ape->frames[ape->currentframe].size);

    pkt->pts = ape->frames[ape->currentframe].pts;
    pkt->stream_index = 0;

    /* note: we need to modify the packet size here to handle the last
       packet */
    pkt->size = ret + extra_size;

    ape->currentframe++;

    return 0;
}

static int ape_read_close(AVFormatContext * s)
{
    APEContext *ape = s->priv_data;

    av_freep(&ape->frames);
    av_freep(&ape->seektable);
    return 0;
}

static int ape_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
{
    AVStream *st = s->streams[stream_index];
    APEContext *ape = s->priv_data;
    int index = av_index_search_timestamp(st, timestamp, flags);

    if (index < 0)
        return -1;

    ape->currentframe = index;
    return 0;
}

AVInputFormat ape_demuxer = {
    "ape",
    "Monkey's Audio",
    sizeof(APEContext),
    ape_probe,
    ape_read_header,
    ape_read_packet,
    ape_read_close,
    ape_read_seek,
    .extensions = "ape,apl,mac"
};