swscale.cc

/*
* copyright (c) 2017 老衲不出家
*
* 2017-08-11
*
*/

#include <stdio.h>
#include <stdint.h>
#include <string.h>

extern "C"
{
#include "libswscale/swscale.h" 
#include "libavutil/pixfmt.h"
}

const char *srcFileName = "ds_480x272.yuv";
const char *dstFileName = "ds_720x576.yuv";

int main()
{
	// 設定原始 YUV 的長寬 
	const int in_width = 480;
	const int in_height = 272;


	// 設定目的 YUV 的長寬 
	const int out_width = 720;
	const int out_height = 576;

	const int read_size = in_width * in_height * 3 / 2;
	const int write_size = out_width * out_height * 3 / 2;
	struct SwsContext *img_convert_ctx = nullptr;

	uint8_t *inbuf[4];
	uint8_t *outbuf[4];

	int inlinesize[4] = { in_width, in_width / 2, in_width / 2, 0 };
	int outlinesize[4] = { out_width, out_width / 2, out_width / 2, 0 };

	uint8_t *ptr_src_yuv_buf = nullptr;
	uint8_t *ptr_dst_yuv_buf = nullptr;
	ptr_src_yuv_buf = new uint8_t[in_width * in_height * 3/2];
	ptr_dst_yuv_buf = new uint8_t[out_width * out_height * 3 /2];

	FILE *fin = fopen(srcFileName, "rb");
	FILE *fout = fopen(dstFileName, "wb");

	if (fin == NULL) {
		fprintf(stderr, "open input file %s error.\n", srcFileName);
		return -1;
	}

	if (fout == NULL) {
		fprintf(stderr, "open output file %s error.\n", dstFileName);
		return -1;
	}

	inbuf[0] = (uint8_t *)malloc(in_width*in_height);
	inbuf[1] = (uint8_t *)malloc(in_width*in_height >> 2);
	inbuf[2] = (uint8_t *)malloc(in_width*in_height >> 2);
	inbuf[3] = NULL;

	outbuf[0] = (uint8_t *)malloc(out_width*out_height);
	outbuf[1] = (uint8_t *)malloc(out_width*out_height >> 2);
	outbuf[2] = (uint8_t *)malloc(out_width*out_height >> 2);
	outbuf[3] = NULL;

	// ********* Initialize software scaling ********* 
	// ********* sws_getContext ********************** 
	img_convert_ctx = sws_getContext(in_width, in_height, AV_PIX_FMT_YUV420P,
		out_width, out_height, AV_PIX_FMT_YUV420P, SWS_POINT, nullptr, nullptr, nullptr);
	if (img_convert_ctx == NULL) {
		fprintf(stderr, "Cannot initialize the conversion context!\n");
		return -1;
	}

	int32_t in_y_size = in_width*in_height;
	int32_t out_y_size;

	bool bExit = false;
	while (!bExit) {

		if ((fread(ptr_src_yuv_buf, 1, read_size, fin) < 0) || (feof(fin))) {
			bExit = true;
			break;
		}

		memcpy(inbuf[0], ptr_src_yuv_buf, in_y_size);
		memcpy(inbuf[1], ptr_src_yuv_buf + in_y_size, in_y_size/4);
		memcpy(inbuf[2], ptr_src_yuv_buf + in_y_size*5/4, in_y_size / 4);

		// ********* 主要的 function ****** 
		// ********* sws_scale ************ 
		sws_scale(img_convert_ctx, inbuf, inlinesize,
			0, in_height, outbuf, outlinesize);

		memcpy(ptr_dst_yuv_buf, outbuf[0], out_width*out_height);
		memcpy(ptr_dst_yuv_buf + out_width*out_height, outbuf[1], out_width*out_height >> 2);
		memcpy(ptr_dst_yuv_buf + (out_width*out_height * 5 >> 2), outbuf[2], out_width*out_height >> 2);

		fwrite(ptr_dst_yuv_buf, 1, write_size, fout);
	}
	// ********* 結束的 function ******* 
	// ********* sws_freeContext ******* 
	sws_freeContext(img_convert_ctx);

	fclose(fin);
	fclose(fout);

	delete[] ptr_src_yuv_buf;
	ptr_src_yuv_buf = nullptr;

	delete[] ptr_dst_yuv_buf;
	ptr_dst_yuv_buf = nullptr;

	return 0;
}