RGB24是表明图像以RGB三原色，每个像素点3个字节表示的一种图像存储格式
注意：在内存中RGB各分量的排列顺序为：BGR BGR BGR
先用ffmpeg生成一个RGB24的图片，命令如下：
ffmpeg -i test.jpg -pix_fmt rgb24 test.rgb
生成后下面用C++代码拆分RGB24的三原色并保存：
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void read_split_rgbfile(const char* file, int width, int height, int frames) { FILE* rgbFp = fopen(file, "rb+"); FILE* rFp = fopen("e:\\test_r.y", "wb+"); FILE* gFp = fopen("e:\\test_g.y", "wb+"); FILE* bFp = fopen("e:\\test_b.y", "wb+"); int size = width * height; unsigned char * buf = (unsigned char*)malloc(size * 3); unsigned char * rbuf = (unsigned char*)malloc(size); unsigned char * gbuf = (unsigned char*)malloc(size); unsigned char * bbuf = (unsigned char*)malloc(size); int ridx, gidx, bidx; ridx = gidx = bidx = 0; for (int i = 0; i < frames; i++) { fread(buf, 1, size * 3, rgbFp); for (int rgbidx = 0; rgbidx < size * 3; rgbidx = rgbidx + 3) { rbuf[ridx++] = buf[rgbidx]; gbuf[gidx++] = buf[rgbidx + 1]; bbuf[bidx++] = buf[rgbidx + 2]; } fwrite(rbuf, 1, size, rFp); fwrite(gbuf, 1, size, gFp); fwrite(bbuf, 1, size, bFp); } free(buf); free(rbuf); free(gbuf); free(bbuf); fclose(rgbFp); fclose(rFp); fclose(gFp); fclose(bFp);} |
用YUVPlayer使用Y通道分别查看R,G,B三原色文件，如果均能显示即表示生成没有问题
由此可以学习RGB三原色在文件中的存储方式
RGB24转储为BMP文件
BMP文件格式为：
BMP文件头+BMP文件信息头+RGB三原色（注意：此时存储序列为BGRBGRBGR.....）
BMP文件头如下：
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typedef struct tagBITMAPFILEHEADER{ UINT16 bfType; DWORD bfSize; UINT16 bfReserved1; UINT16 bfReserved2; DWORD bfOffBits;} BITMAPFILEHEADER; |
BMP文件信息头如下：
调色板可略
使用C++代码将RGB数据转储为BMP文件代码如下：
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typedef struct{ long imageSize; long blank; long startPos;}BMPHead;typedef struct { long length; long width; long height; unsigned short colorPlane; unsigned short bitColor; long zipFormat; long realSize; long xPels; long yPels; long colorUse; long colorImportant;}INFOHead;void muxer_rgb24_to_bmp(const char* rgbfile, int width, int height, const char * bmpfile) { FILE* rgbFp = fopen(rgbfile, "rb+"); FILE* bmpFp = fopen(bmpfile, "wb+"); int size = width * height; char bmpType[] = { 'B','M' }; BMPHead bHead = { 0 }; INFOHead bIHead = { 0 }; int head_length = sizeof(bmpType) + sizeof(BMPHead) + sizeof(INFOHead); bHead.imageSize = size * 3 + head_length; bHead.startPos = head_length; bIHead.length = sizeof(INFOHead); bIHead.width = width; bIHead.height = -height; //注意此处的高度为负 bIHead.colorPlane = 1; bIHead.bitColor = 24; bIHead.realSize = size * 3; fwrite(bmpType, 1, sizeof(bmpType), bmpFp); fwrite(&bHead, 1, sizeof(BMPHead), bmpFp); fwrite(&bIHead, 1, sizeof(INFOHead), bmpFp); unsigned char* rgbBuf = (unsigned char*)malloc(size * 3); fread(rgbBuf, 1, size * 3, rgbFp); for (int i=0;i <size*3;i+=3) //调整R和B的顺序 { int tmp = rgbBuf[i]; rgbBuf[i] = rgbBuf[i + 2]; rgbBuf[i + 2] = tmp; } fwrite(rgbBuf, 1, size * 3, bmpFp); free(rgbBuf); fclose(bmpFp); fclose(rgbFp);} |
输出文件为BMP文件，可以直接查看生成是否正确