return srcSliceH;
static void bgr24toyv12Wrapper(SwsContext *c, uint8_t* src[], int srcStride[], int srcSliceY,             int srcSliceH, uint8_t* dst[], int dstStride[]){	rgb24toyv12(		src[0], 		dst[0]+ srcSliceY    *dstStride[0], 		dst[1]+(srcSliceY>>1)*dstStride[1], 		dst[2]+(srcSliceY>>1)*dstStride[2],		c->srcW, srcSliceH, 		dstStride[0], dstStride[1], srcStride[0]);}