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i.mx6dl h263 encoding and RTP packet

Question asked by Woogeun Shin on Feb 23, 2015
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Hi,

 

I met packet fragmentation error when our RTP generator creates RTP packet from encoded h263 data.

Our product uses h263 codec to send and receive video data to and from network.

Prior to send video data, our RTP generator creates RTP packet from encoded h263 data.

If GOB size of encoded h263 data is larger than 1454 bytes, RTP generator fragments encoded h263 data at MB boundaries.

* MB (MacroBlock)

* 1454 bytes is the maximum RTP payload size.

During this fragmentation, error was happened.

It's not happen for every packet. It's happened only for some packets larger than MTU.

The main error reason is two. They are "not found CBPY", " Not found TCOEF"

* CBPY(Coded Block Pattern for Luminance",   TCOEF(Transform Coefficient".

Our RTP generator is verified with other CPU like galaxy, G series and TCC.

But, the operation with Freescale CPU is the first time.

 

When i tested with original VPU library, almost packets were dropped during fragmentation.

Its GOB size of dropped encoded data was larger than 1454 bytes.

So, i checked the VPU API document. I noticed sliceMode.

The sliceMode of original VPU library was disabled

So, i enabled sliceMode with below value.

   sliceMode=1, sliceSize=1400.

After enable sliceMode, the fragmentation error was decreased clearly.

But the error was still happened for large GOB data over 1454 bytes.

 

I haven't seen case of h263 codec usage with RTP stream.

 

If anybody has experience h263 video data send and receive through network with imx6, please share your experience.

 

Regards,

Shin.

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