int av_grow_packet(AVPacket *pkt, int grow_by)
{
    int new_size;
    av_assert0((unsigned)pkt->size <= INT_MAX - FF_INPUT_BUFFER_PADDING_SIZE);
    if (!pkt->size)
        return av_new_packet(pkt, grow_by);
    if ((unsigned)grow_by >
        INT_MAX - (pkt->size + FF_INPUT_BUFFER_PADDING_SIZE))
        return -1;

    new_size = pkt->size + grow_by + FF_INPUT_BUFFER_PADDING_SIZE;
    if (pkt->buf) {
        int ret = av_buffer_realloc(&pkt->buf, new_size);
        if (ret < 0)
            return ret;
    } else {
        pkt->buf = av_buffer_alloc(new_size);
        if (!pkt->buf)
            return AVERROR(ENOMEM);
        memcpy(pkt->buf->data, pkt->data, FFMIN(pkt->size, pkt->size + grow_by));
#if FF_API_DESTRUCT_PACKET
FF_DISABLE_DEPRECATION_WARNINGS
        pkt->destruct = dummy_destruct_packet;
FF_ENABLE_DEPRECATION_WARNINGS
#endif
    }
    pkt->data  = pkt->buf->data;
    pkt->size += grow_by;
    memset(pkt->data + pkt->size, 0, FF_INPUT_BUFFER_PADDING_SIZE);

    return 0;
}