ffmpeg 轉 RGB 填充 bitmap

sws_scale( img_convert_ctx, 
          pVideoFrame[nChannel]->data, 
  pVideoFrame[nChannel]->linesize, 
                          0, 
  pCodeContext[nChannel]->height, 
  pRGBFrame->data, 
  pRGBFrame->linesize); 

CreateBmp(szFileName, pRGBFrame->data[0], 
            pCodeContext[nChannel]->width, 
pCodeContext[nChannel]->height, 
24) 

BOOL CreateBmp(char *filename, uint8_t *pRGBBuffer, int width, int height, int bpp) 
{ 
BITMAPFILEHEADER bmpheader; 
BITMAPINFO bmpinfo; 
FILE *fp = NULL; 

fp = fopen(filename,"wb"); 
if( fp == NULL ) 
{ 
return FALSE; 
} 

bmpheader.bfType = ('M' < <8)|'B'; 
bmpheader.bfReserved1 = 0; 
bmpheader.bfReserved2 = 0; 
bmpheader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER); 
bmpheader.bfSize = bmpheader.bfOffBits + width*height*bpp/8; 

bmpinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER); 
bmpinfo.bmiHeader.biWidth = width; 
bmpinfo.bmiHeader.biHeight = height; 
bmpinfo.bmiHeader.biPlanes = 1; 
bmpinfo.bmiHeader.biBitCount = bpp; 
bmpinfo.bmiHeader.biCompression = BI_RGB; 
bmpinfo.bmiHeader.biSizeImage = 0; 
bmpinfo.bmiHeader.biXPelsPerMeter = 100; 
bmpinfo.bmiHeader.biYPelsPerMeter = 100; 
bmpinfo.bmiHeader.biClrUsed = 0; 
bmpinfo.bmiHeader.biClrImportant = 0; 

fwrite(&bmpheader,sizeof(BITMAPFILEHEADER),1,fp); 
fwrite(&bmpinfo.bmiHeader,sizeof(BITMAPINFOHEADER),1,fp); 
fwrite(pRGBBuffer,width*height*bpp/8,1,fp); 
fclose(fp); 
fp = NULL; 

return TRUE; 
} 

這個問題第1個回答：
bmpinfo.bmiHeader.biHeight = -height;
這個問題第2個回答：
倒立才是對的,bmp的圖象資料是從下至上的