public static extern int av_bitstream_filter_filter(ref AVBitStreamFilterContext pAVBitStreamFilterContext,
ref AVCodec pAVCodecContext,
string args,
ref byte[] poutbuf,
ref int poutbuf_size, byte[] buf, int buf_size, int keyframe);
public static extern void av_bitstream_filter_close(ref AVBitStreamFilterContext pAVBitStreamFilterContext);