static int noise(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args,
                     uint8_t **poutbuf, int *poutbuf_size,
                     const uint8_t *buf, int buf_size, int keyframe){
    unsigned int *state= bsfc->priv_data;
    int amount= args ? atoi(args) : (*state % 10001+1);
    int i;
    *poutbuf= av_malloc(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
    memcpy(*poutbuf, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
    for(i=0; i<buf_size; i++){
        (*state) += (*poutbuf)[i] + 1;
        if(*state % amount == 0)
            (*poutbuf)[i] = *state;
    }
    return 1;
}