public static extern void sws_freeFilter(SwsFilter* filter);
public static extern SwsContext* sws_getCachedContext(SwsContext* context, int srcW, int srcH, AVPixelFormat srcFormat, int dstW, int dstH, AVPixelFormat dstFormat, int flags, SwsFilter* srcFilter, SwsFilter* dstFilter, double* param);
public static extern int sws_init_context(SwsContext* sws_context, SwsFilter* srcFilter, SwsFilter* dstFilter);