VideoHelp Forum

Try DVDFab and download streaming video, copy, convert or make Blu-rays,DVDs! Download free trial !
+ Reply to Thread
Results 1 to 5 of 5
Thread
  1. Hello , i'm using the cisco OpenH264 codec in coding and decoding process , the coding stage works very well and i can read my encoded H.264 file correctly , the issue is with my decoding process and mainly the conversion from I420 to ARGB , please can any one helps to fix this .

    Here's my Decoding function ( from the OpenH264 wrapper DLL ) :

    Code:
    /*
    * [ IN ]   SourceData : the encoded frame(s)
    * [ OUT ] pTargetbuffer : the Target buffer 
    * [ OUT ] width
    * [ OUT ] height
    */
    int H264Decoder_decode(BufferedData &SourceData, void *pTargetbuffer, int *width, int *height) {
    
     	int iStride[2];
    	init();
    
             ... the decoding routine : pData contains the YUV 
    
            if (ret != dsErrorFree) {
    
    			return -1;
    		}
    		if (!m_sBufferInfo.iBufferStatus) {
    			return -2;
    		}
    
            LWidth = m_sBufferInfo.UsrData.sSystemBuffer.iWidth;
    	LHeight = m_sBufferInfo.UsrData.sSystemBuffer.iHeight;
    	*width = LWidth;
    	*height = LHeight;
    
    	  iStride[0] = m_sBufferInfo.UsrData.sSystemBuffer.iStride[0];
    	  iStride[1] = m_sBufferInfo.UsrData.sSystemBuffer.iStride[1];
    			   
                   /*
    		BOOL I420ToARGB(const unsigned char *src_y, int src_stride_y,
                    const unsigned char *src_u, int src_stride_u,
                    const unsigned char *src_v, int src_stride_v,
                    unsigned char *dst_frame, int dst_stride_frame,
                    int width, int height);
    		*/
    
    		I420ToARGB(
    		(unsigned char *)pData[0],iStride[0],
    		(unsigned char *)pData[1],iStride[1],
    		(unsigned char *)pData[2],iStride[1],
    		(unsigned char *)pTargetbuffer,
                    /*
                    * if i put LWidth*4 which is the correct way to get the real pixel i get an AV in delphi
                    * and i think the AV is not related to delphi but the OpenH264 itself
                    */
    		LWidth*2,
    		LWidth,LHeight);
    			
    		return 0;
    }
    and here's my Delphi implementation :

    Code:
      Image.Picture.Bitmap.PixelFormat := pf24bit;
      Image.Picture.Bitmap.Width  := 320;
      Image.Picture.Bitmap.Height := 240;
    ...
    Result:=H264Decoder_decode(FEncodedBuffer,
                            Image.Picture.Bitmap.ScanLine[Image.Picture.Bitmap.Height-1],
                            EncodedBufferSize,LWidth,LHeight); 
    						
    if result=0 then Image.Repaint;


    So many thanks .
    yours,Randy
    Last edited by randydom; 1st Dec 2017 at 01:42.
    Quote Quote  
  2. If i understand correctly your problem then I420 use 12 bits per pixel (U and V are 1/4 size each of the Y plane size), ARGB use 32 bits per pixel. before converting YUV (or correctly YCbCr) you should upscale plane U and V to size of plane Y (this sampling scheme is called 4:4:4). A is Alpha plane and it doesn't exist in your YUV source so you need to create it as empty table filled with constant.
    If i misunderstood your problem then sorry.
    Quote Quote  
  3. Originally Posted by pandy View Post
    If i understand correctly your problem then I420 use 12 bits per pixel (U and V are 1/4 size each of the Y plane size), ARGB use 32 bits per pixel. before converting YUV (or correctly YCbCr) you should upscale plane U and V to size of plane Y (this sampling scheme is called 4:4:4). A is Alpha plane and it doesn't exist in your YUV source so you need to create it as empty table filled with constant.
    If i misunderstood your problem then sorry.
    so many thanks pandy , can you just give me this step ( in code if possible ) .
    Quote Quote  
  4. so many thanks i've fixed it , the issue was that i used :
    Code:
    Image.Picture.Bitmap.PixelFormat := pf24bit;
    but the correct PixelFormat is :
    Code:
    PixelFormat is the pf32bit
    Thank you again
    Quote Quote  



Similar Threads