ffmpeg libswscale实现YUV转RGB

//使用参数初始化SwsContext结构体
sws_getContext()
//转换一帧图像
sws_scale()
//释放SwsContext结构体
sws_freeContext()

//为SwsContext结构体分配内存
sws_alloc_context()
//设置SwsContext结构体的值
av_opt_set()/av_opt_set_XXX()
//初始化SwsContext结构体。
sws_init_context()

//可以获得指定像素格式的AVPixFmtDescriptor结构体
av_pix_fmt_desc_get()
//通过AVPixFmtDescriptor获取值
av_get_bits_per_pixel() //获取比特数（bpp）

SWS_BICUBIC性能比较好；SWS_FAST_BILINEAR在性能和速度之间有一个比好好的平衡。

#include "stdafx.h"


extern "C" {
	#include <libswscale/swscale.h>
	#include <libavutil/opt.h>
	#include <libavutil/imgutils.h>
}


void p(const char * msg, int d = -1123) {
	if (d == -1123) {
		printf_s("%s\n", msg);
	}
	else {
		printf_s("%s  %d \n", msg, d);
	}
}


int yuv2Rgb(FILE *yuvFile,FILE * rgbFile) {

	SwsContext *img_convert_ctx = NULL;

	const AVPixelFormat srcPixelFormat = AV_PIX_FMT_YUV420P;
	const AVPixelFormat dstPixelFormat = AV_PIX_FMT_RGB24;

	const int srcW = 1080;
	const int srcH= 720;

	const int dstW = 540;
	const int dstH = 360;

	uint8_t *src_data[4];
	int src_linesize[4];

	uint8_t *dst_data[4];
	int dst_linesize[4];


	//1. 获得指定像素格式的AVPixFmtDescriptor结构体
	const AVPixFmtDescriptor * pSrcPixFmtDes = av_pix_fmt_desc_get(srcPixelFormat);
	//2. 获得指定像素格式每个像素占用的比特数bpp（Bit Per Pixel） 
	int srcBpp=  av_get_bits_per_pixel(pSrcPixFmtDes);

	const AVPixFmtDescriptor * pDstPixFmtDes = av_pix_fmt_desc_get(dstPixelFormat);
	int dstBpp = av_get_bits_per_pixel(pDstPixFmtDes);


	

	//3. 根据宽高，像素格式分配buffer大小
	if (av_image_alloc(src_data, src_linesize, srcW, srcH, srcPixelFormat, 1) < 0) {
		p("Could not allocate source image");
		return -1;
	}

	if (av_image_alloc(dst_data, dst_linesize, dstW, dstH, dstPixelFormat, 1) < 0) {
		p("Could not allocate source image");
		return -1;
	}

	//4. 为SwsContext结构体分配内存。
	img_convert_ctx = sws_alloc_context();
	//Show AVOption
	av_opt_show2(img_convert_ctx, stdout, AV_OPT_FLAG_VIDEO_PARAM, 0);




	//图像拉伸   SWS_BICUBIC性能比较好；SWS_FAST_BILINEAR在性能和速度之间有一个比好好的平衡。
	//const int rescale_method = SWS_BICUBIC;
	//5. 设置值
	av_opt_set_int(img_convert_ctx, "sws_flags", SWS_BICUBIC | SWS_PRINT_INFO, 0);
	av_opt_set_int(img_convert_ctx, "srcw", srcW, 0);
	av_opt_set_int(img_convert_ctx, "srch", srcH, 0);
	av_opt_set_int(img_convert_ctx, "src_format", srcPixelFormat, 0);
	//'0' for MPEG (Y:0-235);'1' for JPEG (Y:0-255)
	av_opt_set_int(img_convert_ctx, "src_range", 1, 0);
	av_opt_set_int(img_convert_ctx, "dstw", dstW, 0);
	av_opt_set_int(img_convert_ctx, "dsth", dstH, 0);
	av_opt_set_int(img_convert_ctx, "dst_format", dstPixelFormat, 0);
	av_opt_set_int(img_convert_ctx, "dst_range", 1, 0);
	sws_init_context(img_convert_ctx, NULL, NULL);//对SwsContext中的各种变量进行赋值

	
	uint8_t *temp_buffer = (uint8_t *)malloc(srcW *srcH *srcBpp / 8);

	int frame_idx = 0;
	while (1){
		if (fread(temp_buffer, 1, srcW*srcH*srcBpp / 8, yuvFile) != srcW * srcH*srcBpp / 8) {
			break;
		}

		switch (srcPixelFormat) {
			case AV_PIX_FMT_GRAY8: {
				memcpy(src_data[0], temp_buffer, srcW*srcH);
				break;
			}
			case AV_PIX_FMT_YUV420P: {
				memcpy(src_data[0], temp_buffer, srcW*srcH);                    //Y
				memcpy(src_data[1], temp_buffer + srcW * srcH, srcW*srcH / 4);      //U
				memcpy(src_data[2], temp_buffer + srcW * srcH * 5 / 4, srcW*srcH / 4);  //V
				break;
			}
			case AV_PIX_FMT_YUV422P: {
				memcpy(src_data[0], temp_buffer, srcW*srcH);                    //Y
				memcpy(src_data[1], temp_buffer + srcW * srcH, srcW*srcH / 2);      //U
				memcpy(src_data[2], temp_buffer + srcW * srcH * 3 / 2, srcW*srcH / 2);  //V
				break;
			}
			case AV_PIX_FMT_YUV444P: {
				memcpy(src_data[0], temp_buffer, srcW*srcH);                    //Y
				memcpy(src_data[1], temp_buffer + srcW * srcH, srcW*srcH);        //U
				memcpy(src_data[2], temp_buffer + srcW * srcH * 2, srcW*srcH);      //V
				break;
			}
			case AV_PIX_FMT_YUYV422: {
				memcpy(src_data[0], temp_buffer, srcW*srcH * 2);                  //Packed
				break;
			}
			case AV_PIX_FMT_RGB24: {
				memcpy(src_data[0], temp_buffer, srcW*srcH * 3);                  //Packed
				break;
			}
			default: {
				printf("Not Support Input Pixel Format.\n");
				break;
			}
		}

		sws_scale(img_convert_ctx, src_data, src_linesize, 0, srcH, dst_data, dst_linesize);//转换像素
		printf("Finish process frame %5d\n", frame_idx);
		frame_idx++;

		switch (dstPixelFormat) {
			case AV_PIX_FMT_GRAY8: {
				fwrite(dst_data[0], 1, dstW*dstH, rgbFile);
				break;
			}
			case AV_PIX_FMT_YUV420P: {
				fwrite(dst_data[0], 1, dstW*dstH, rgbFile);                 //Y
				fwrite(dst_data[1], 1, dstW*dstH / 4, rgbFile);               //U
				fwrite(dst_data[2], 1, dstW*dstH / 4, rgbFile);               //V
				break;
			}
			case AV_PIX_FMT_YUV422P: {
				fwrite(dst_data[0], 1, dstW*dstH, rgbFile);                 //Y
				fwrite(dst_data[1], 1, dstW*dstH / 2, rgbFile);               //U
				fwrite(dst_data[2], 1, dstW*dstH / 2, rgbFile);               //V
				break;
			}
			case AV_PIX_FMT_YUV444P: {
				fwrite(dst_data[0], 1, dstW*dstH, rgbFile);                 //Y
				fwrite(dst_data[1], 1, dstW*dstH, rgbFile);                 //U
				fwrite(dst_data[2], 1, dstW*dstH, rgbFile);                 //V
				break;
			}
			case AV_PIX_FMT_YUYV422: {
				fwrite(dst_data[0], 1, dstW*dstH * 2, rgbFile);               //Packed
				break;
			}
			case AV_PIX_FMT_RGB24: {
				fwrite(dst_data[0], 1, dstW*dstH * 3, rgbFile);               //Packed
				break;
			}
			default: {
				p("Not Support Output Pixel Format.\n");
				break;
			}
		}
	}

	sws_freeContext(img_convert_ctx);
	free(temp_buffer);
	av_freep(&src_data[0]);
	av_freep(&dst_data[0]);

	return 0;


}


int main() {
	FILE* inFile;
	FILE* outFile;
	fopen_s(&inFile,"F:/视频资源/gxsp.yuv", "rb");
	fopen_s(&outFile, "F:/视频资源/gxsp.rgb", "wb");
	yuv2Rgb(inFile,outFile);

	fclose(inFile);
	fclose(outFile);

	getchar();

	return 0;
}