static int get_avc_nalsize(H264Context *h, const uint8_t *buf,

                           int buf_size, int *buf_index)

{

    int i, nalsize = 0;



    if (*buf_index >= buf_size - h->nal_length_size)

        return -1;



    for (i = 0; i < h->nal_length_size; i++)

        nalsize = (nalsize << 8) | buf[(*buf_index)++];

    if (nalsize <= 0 || nalsize > buf_size - *buf_index) {

        av_log(h->avctx, AV_LOG_ERROR,

               "AVC: nal size %d\n", nalsize);

        return -1;

    }

    return nalsize;

}
