static int mlp_parse(AVCodecParserContext *s,

                     AVCodecContext *avctx,

                     const uint8_t **poutbuf, int *poutbuf_size,

                     const uint8_t *buf, int buf_size)

{

    MLPParseContext *mp = s->priv_data;

    int sync_present;

    uint8_t parity_bits;

    int next;

    int i, p = 0;



    *poutbuf_size = 0;

    if (buf_size == 0)

        return 0;



    if (!mp->in_sync) {

        // Not in sync - find a major sync header



        for (i = 0; i < buf_size; i++) {

            mp->pc.state = (mp->pc.state << 8) | buf[i];

            if ((mp->pc.state & 0xfffffffe) == 0xf8726fba &&

                // ignore if we do not have the data for the start of header

                mp->pc.index + i >= 7) {

                mp->in_sync = 1;

                mp->bytes_left = 0;

                break;

            }

        }



        if (!mp->in_sync) {

            if (ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size) != -1)

                av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");

            return buf_size;

        }



        ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size);



        return i - 7;

    }



    if (mp->bytes_left == 0) {

        // Find length of this packet



        /* Copy overread bytes from last frame into buffer. */

        for(; mp->pc.overread>0; mp->pc.overread--) {

            mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++];

        }



        if (mp->pc.index + buf_size < 2) {

            if (ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size) != -1)

                av_log(avctx, AV_LOG_WARNING, "ff_combine_frame failed\n");

            return buf_size;

        }



        mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8)

                       |  (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]);

        mp->bytes_left = (mp->bytes_left & 0xfff) * 2;

        if (mp->bytes_left <= 0) { // prevent infinite loop

            goto lost_sync;

        }

        mp->bytes_left -= mp->pc.index;

    }



    next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left;



    if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) {

        mp->bytes_left -= buf_size;

        return buf_size;

    }



    mp->bytes_left = 0;



    sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba;



    if (!sync_present) {

        /* The first nibble of a frame is a parity check of the 4-byte

         * access unit header and all the 2- or 4-byte substream headers. */

        // Only check when this isn't a sync frame - syncs have a checksum.



        parity_bits = 0;

        for (i = -1; i < mp->num_substreams; i++) {

            parity_bits ^= buf[p++];

            parity_bits ^= buf[p++];



            if (i < 0 || buf[p-2] & 0x80) {

                parity_bits ^= buf[p++];

                parity_bits ^= buf[p++];

            }

        }



        if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) {

            av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n");

            goto lost_sync;

        }

    } else {

        GetBitContext gb;

        MLPHeaderInfo mh;



        init_get_bits(&gb, buf + 4, (buf_size - 4) << 3);

        if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0)

            goto lost_sync;



        avctx->bits_per_raw_sample = mh.group1_bits;

        if (avctx->bits_per_raw_sample > 16)

            avctx->sample_fmt = AV_SAMPLE_FMT_S32;

        else

            avctx->sample_fmt = AV_SAMPLE_FMT_S16;

        avctx->sample_rate = mh.group1_samplerate;

        s->duration = mh.access_unit_size;



        if(!avctx->channels || !avctx->channel_layout) {

        if (mh.stream_type == 0xbb) {

            /* MLP stream */

#if FF_API_REQUEST_CHANNELS

FF_DISABLE_DEPRECATION_WARNINGS

            if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&

                mh.num_substreams > 1) {

                avctx->channels       = 2;

                avctx->channel_layout = AV_CH_LAYOUT_STEREO;

FF_ENABLE_DEPRECATION_WARNINGS

            } else

#endif

            if (avctx->request_channel_layout &&

                (avctx->request_channel_layout & AV_CH_LAYOUT_STEREO) ==

                avctx->request_channel_layout &&

                mh.num_substreams > 1) {

                avctx->channels       = 2;

                avctx->channel_layout = AV_CH_LAYOUT_STEREO;

            } else {

                avctx->channels       = mh.channels_mlp;

                avctx->channel_layout = mh.channel_layout_mlp;

            }

        } else { /* mh.stream_type == 0xba */

            /* TrueHD stream */

#if FF_API_REQUEST_CHANNELS

FF_DISABLE_DEPRECATION_WARNINGS

            if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&

                mh.num_substreams > 1) {

                avctx->channels       = 2;

                avctx->channel_layout = AV_CH_LAYOUT_STEREO;

            } else if (avctx->request_channels > 0 &&

                       avctx->request_channels <= mh.channels_thd_stream1) {

                avctx->channels       = mh.channels_thd_stream1;

                avctx->channel_layout = mh.channel_layout_thd_stream1;

FF_ENABLE_DEPRECATION_WARNINGS

            } else

#endif

                if (avctx->request_channel_layout &&

                    (avctx->request_channel_layout & AV_CH_LAYOUT_STEREO) ==

                    avctx->request_channel_layout &&

                    mh.num_substreams > 1) {

                avctx->channels       = 2;

                avctx->channel_layout = AV_CH_LAYOUT_STEREO;

            } else if (!mh.channels_thd_stream2 ||

                       (avctx->request_channel_layout &&

                        (avctx->request_channel_layout & mh.channel_layout_thd_stream1) ==

                        avctx->request_channel_layout)) {

                avctx->channels       = mh.channels_thd_stream1;

                avctx->channel_layout = mh.channel_layout_thd_stream1;

            } else {

                avctx->channels       = mh.channels_thd_stream2;

                avctx->channel_layout = mh.channel_layout_thd_stream2;

            }

        }

        }



        if (!mh.is_vbr) /* Stream is CBR */

            avctx->bit_rate = mh.peak_bitrate;



        mp->num_substreams = mh.num_substreams;

    }



    *poutbuf = buf;

    *poutbuf_size = buf_size;



    return next;



lost_sync:

    mp->in_sync = 0;

    return 1;

}
