int ff_h2645_packet_split(H2645Packet *pkt, const uint8_t *buf, int length,
                          void *logctx, int is_nalff, int nal_length_size,
                          enum AVCodecID codec_id, int small_padding)
{
    int consumed, ret = 0;
    const uint8_t *next_avc = is_nalff ? buf : buf + length;

    pkt->nb_nals = 0;
    while (length >= 4) {
        H2645NAL *nal;
        int extract_length = 0;
        int skip_trailing_zeros = 1;

        if (buf == next_avc) {
            int i;
            for (i = 0; i < nal_length_size; i++)
                extract_length = (extract_length << 8) | buf[i];
            buf    += nal_length_size;
            length -= nal_length_size;

            if (extract_length > length) {
                av_log(logctx, AV_LOG_ERROR, "Invalid NAL unit size.\n");
                return AVERROR_INVALIDDATA;
            }
            next_avc = buf + extract_length;
        } else {
            if (buf > next_avc)
                av_log(logctx, AV_LOG_WARNING, "Exceeded next NALFF position, re-syncing.\n");

            /* search start code */
            while (buf[0] != 0 || buf[1] != 0 || buf[2] != 1) {
                ++buf;
                --length;
                if (length < 4) {
                    if (pkt->nb_nals > 0) {
                        // No more start codes: we discarded some irrelevant
                        // bytes at the end of the packet.
                        return 0;
                    } else {
                        av_log(logctx, AV_LOG_ERROR, "No start code is found.\n");
                        return AVERROR_INVALIDDATA;
                    }
                } else if (buf >= (next_avc - 3))
                    break;
            }

            buf           += 3;
            length        -= 3;
            extract_length = FFMIN(length, next_avc - buf);

            if (buf >= next_avc) {
                /* skip to the start of the next NAL */
                int offset = next_avc - buf;
                buf    += offset;
                length -= offset;
                continue;
            }
        }

        if (pkt->nals_allocated < pkt->nb_nals + 1) {
            int new_size = pkt->nals_allocated + 1;
            void *tmp = av_realloc_array(pkt->nals, new_size, sizeof(*pkt->nals));

            if (!tmp)
                return AVERROR(ENOMEM);

            pkt->nals = tmp;
            memset(pkt->nals + pkt->nals_allocated, 0,
                   (new_size - pkt->nals_allocated) * sizeof(*pkt->nals));

            nal = &pkt->nals[pkt->nb_nals];
            nal->skipped_bytes_pos_size = 1024; // initial buffer size
            nal->skipped_bytes_pos = av_malloc_array(nal->skipped_bytes_pos_size, sizeof(*nal->skipped_bytes_pos));
            if (!nal->skipped_bytes_pos)
                return AVERROR(ENOMEM);

            pkt->nals_allocated = new_size;
        }
        nal = &pkt->nals[pkt->nb_nals];

        consumed = ff_h2645_extract_rbsp(buf, extract_length, nal, small_padding);
        if (consumed < 0)
            return consumed;

        if (is_nalff && (extract_length != consumed) && extract_length)
            av_log(logctx, AV_LOG_DEBUG,
                   "NALFF: Consumed only %d bytes instead of %d\n",
                   consumed, extract_length);

        pkt->nb_nals++;

        /* see commit 3566042a0 */
        if (consumed < length - 3 &&
            buf[consumed]     == 0x00 && buf[consumed + 1] == 0x00 &&
            buf[consumed + 2] == 0x01 && buf[consumed + 3] == 0xE0)
            skip_trailing_zeros = 0;

        nal->size_bits = get_bit_length(nal, skip_trailing_zeros);

        ret = init_get_bits(&nal->gb, nal->data, nal->size_bits);
        if (ret < 0)
            return ret;

        if (codec_id == AV_CODEC_ID_HEVC)
            ret = hevc_parse_nal_header(nal, logctx);
        else
            ret = h264_parse_nal_header(nal, logctx);
        if (ret <= 0 || nal->size <= 0) {
            if (ret < 0) {
                av_log(logctx, AV_LOG_ERROR, "Invalid NAL unit %d, skipping.\n",
                       nal->type);
            }
            pkt->nb_nals--;
        }

        buf    += consumed;
        length -= consumed;
    }

    return 0;
}