H264解码之YUV格式转换及缩放

int video_decoder::swscale(const char* srcbuf, int ntype, int nsrcwidth, int nsrcheight, int ndstwidth, int ndstheight, unsigned char* dstbuf)
{
	if (5 != ntype && 3 != ntype)
	{
		return -1;
	}
	if (!srcbuf || !dstbuf)
		return -1;
	AVPixelFormat srcpixfmt = AV_PIX_FMT_YUV420P;
	AVPixelFormat dstpixfmt = AV_PIX_FMT_BGR32;
	uint8_t* src_y = 0;
	uint8_t* src_u = 0;
	uint8_t* src_v = 0;
	if (3 == ntype)
	{
		src_y = (uint8_t*)srcbuf;
		src_v = (uint8_t*)srcbuf + nsrcwidth * nsrcheight;
		src_u = (uint8_t*)srcbuf + nsrcwidth * nsrcheight + nsrcwidth * nsrcheight / 4;
	}
	else
	{
		src_y = (uint8_t*)srcbuf;
		src_u = (uint8_t*)srcbuf + nsrcwidth * nsrcheight;
		src_v = (uint8_t*)srcbuf + nsrcwidth * nsrcheight + nsrcwidth * nsrcheight / 4;
	}
	uint8_t* src[3] = {