FW: [Mp4-tech] Help with H.264 start code prefix

[Rob Koenen]

Forwarding bounced message.
________________________________
From: Madan [mailto:madank interrasystems.com] 
Sent: Tuesday, 26 October 2023 21:16
To: mp4-tech lists.mpegif.org
Cc: video guy
Subject: Re: [Mp4-tech] Help with H.264 start code prefix
Hi Buddy !!
     At the decoder end, keep a buffer that accumulates the
packets from the server.  From this buffer extract the NAL
packets.  From the bitstream at the reciving end. 
Use this algo to extract the NAL units
for(;;)
        {
            if next 24 bits are 0x000001
        {
           startCodeFound = true
           break;
        }
            else
            {
                flush 8 bits 
            }
        }// for(;;)
        if(true == startCodeFound)
        {
            //startcode found
            // Flush the start code found
            flush 24 bits 
            //Now navigate up to next start code and put the in between
stuff
            // in the nal structure.
           for(;;)
           {
               get next 24 bits & check if it equals to 0x000001
              if(false == (next 24 bits == 000001))
               {
                   // search for pattern 0x000000
                   check if next 24 bits are 0x000000
                   if(false == result)
                   {
                       // copy the byte into the buffer
                       copy one byte to the Nal unit 
                   }
                   else
                   {
                       break;
                   }
               }
               else
               {
                   break;
               }
           }//for(;;)
once u got  the nal , decode it ...
Hope this helps u :-)
video guy wrote:
	Hello,
	I'm trying to use the start code prefix in H.264 but not sure
how to go ahead with it.
	Here is my problem,
	I want to send the h.264 encoded byte stream (which is stored as
test.264 file) from one system to another using a client server program
in C, and, simulate a packet loss environment. At the reciever, some
random data will be lost. 
	But, i'm not able to run the decoder due to the lost data. Is
there anyway I could make the decoder work ? I have no idea how to use
the start code prefix. 
	Any help in this regard would be greatly appreciated. 
	Thank you 
	aar.
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-- 
Thanx & Regards !! 
from Madan 
Interra Systems India Pvt. Ltd. 
A10, Sec9,NOIDA Ph: 0120-2442273/4 Ext 324 
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