topic Re: problems with MPEG2 decoder sample in Intel® Integrated Performance Primitives

problems with MPEG2 decoder sample

petemoss — Wed, 18 Mar 2009 21:18:41 GMT

Dear IPP experts, especially those of you with experience using the IPP
MPEG2 decoder.

I had good success using the IPP MPEG2 decoder (from the 5.1 samples) to
decode an MPEG2 stream from a frame grabber.
Recently I tried to use the same decoder to decode a different MPEG2 stream
which arrives in UDP packets. The resultant decoded video has what I would
call decoding artifacts in the form of quite a few areas of 8X8 or 16X16
pixels which are either all the same color, or simple decoded wrong.
Sometimes these squares appear randomly in the image, sometimes they are
adjacent to other squares of similar characteristics.

I wonder if anyone else has had similar experience with the MPEG2 decoder,
and if so how they solved the problem. I can provide an mpg file with the
video recorded. Other players (VLC) can show that mpg file just fine.

Re: problems with MPEG2 decoder sample

Vladimir_Dudnik — Thu, 19 Mar 2009 15:49:12 GMT

What application do you use to decode this MPEG2 stream? Is it UMC simple_player application or it is something developed by you and adopted to receive UPD packets?

Vladimir

Re: problems with MPEG2 decoder sample

petemoss — Fri, 20 Mar 2009 16:01:35 GMT

Quoting - Vladimir Dudnik (Intel)

What application do you use to decode this MPEG2 stream? Is it UMC simple_player application or it is something developed by you and adopted to receive UPD packets?

Vladimir

It is my application using MPEG2VideoDecoder declared in the umc_mpeg2_dec.h file from the samples.
The UDP part has nothing to do with it, as I get the same results when I open the mpg file and read chunks of it into the decoder.

Re: problems with MPEG2 decoder sample

Vladimir_Dudnik — Mon, 23 Mar 2009 17:26:49 GMT

If simple_player is able to decode this MPG file and your application (which reads the file by chunks and supply chunks to IPP decoder) can't the reason might be in the way you splt file to chunks. IPP decoder expect complete compressed frame is available in MediaData in parameter. You may need to accumulate UDP packets untill get complete compressed frame, for example, by looking the next picture start code)

Vladimir