Function parse_common_header

libavcodec/dca_xll.c:777–882

}

static int parse_common_header(DCAXllDecoder *s)
{
    int stream_ver, header_size, frame_size_nbits, nframesegs_log2;

    // XLL extension sync word
    if (get_bits_long(&s->gb, 32) != DCA_SYNCWORD_XLL) {
        av_log(s->avctx, AV_LOG_VERBOSE, "Invalid XLL sync word\n");
        return AVERROR(EAGAIN);
    }

    // Version number
    stream_ver = get_bits(&s->gb, 4) + 1;
    if (stream_ver > 1) {
        avpriv_request_sample(s->avctx, "XLL stream version %d", stream_ver);
        return AVERROR_PATCHWELCOME;
    }

    // Lossless frame header length
    header_size = get_bits(&s->gb, 8) + 1;

    // Check CRC
    if (ff_dca_check_crc(s->avctx, &s->gb, 32, header_size * 8)) {
        av_log(s->avctx, AV_LOG_ERROR, "Invalid XLL common header checksum\n");
        return AVERROR_INVALIDDATA;
    }

    // Number of bits used to read frame size
    frame_size_nbits = get_bits(&s->gb, 5) + 1;

    // Number of bytes in a lossless frame
    s->frame_size = get_bits_long(&s->gb, frame_size_nbits);
    if (s->frame_size < 0 || s->frame_size >= DCA_XLL_PBR_BUFFER_MAX) {
        av_log(s->avctx, AV_LOG_ERROR, "Invalid XLL frame size (%d bytes)\n", s->frame_size);
        return AVERROR_INVALIDDATA;
    }
    s->frame_size++;

    // Number of channels sets per frame
    s->nchsets = get_bits(&s->gb, 4) + 1;
    if (s->nchsets > DCA_XLL_CHSETS_MAX) {
        avpriv_request_sample(s->avctx, "%d XLL channel sets", s->nchsets);
        return AVERROR_PATCHWELCOME;
    }

    // Number of segments per frame
    nframesegs_log2 = get_bits(&s->gb, 4);
    s->nframesegs = 1 << nframesegs_log2;
    if (s->nframesegs > 1024) {
        av_log(s->avctx, AV_LOG_ERROR, "Too many segments per XLL frame\n");
        return AVERROR_INVALIDDATA;
    }

    // Samples in segment per one frequency band for the first channel set
    // Maximum value is 256 for sampling frequencies <= 48 kHz
    // Maximum value is 512 for sampling frequencies > 48 kHz
    s->nsegsamples_log2 = get_bits(&s->gb, 4);
    if (!s->nsegsamples_log2) {
        av_log(s->avctx, AV_LOG_ERROR, "Too few samples per XLL segment\n");