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Is the DNxHD codec mis-designed?

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Matthew Friedman
Is the DNxHD codec mis-designed?
on Jul 12, 2012 at 1:53:29 pm

I don't fully technically understand exactly how codecs work, but I've been having a back and forth with a software developer of a video converter program about Avid's design of the DNx codec. My problem has been that on my 12 core Mac Pro, I can't find a single program (including Media Composer itself) that takes advantage of all my processor cores when converting material to DNxHD.

The developer was complaining that the way in which Avid designed the codec makes it impossible for their software to harness a machine's full processing power in certain situations. Has anyone else come across this?

Thoughts?


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Daniel Frome
Re: Is the DNxHD codec mis-designed?
on Jul 12, 2012 at 2:15:16 pm

I am not a software engineer, but I do know that many of Avid's transcoding functions don't max out all CPU cores like some other software. However, with DNxHD it should be possible. Example: doing a video mixdown inside Avid with DNxHD uses about 70% of my total CPU power (8 core xeon). So... nearly all my cores are being used, just not maxing them out.

I've done transcoding tests on several codecs, and the strange thing is that while DNxHD doesn't use as much CPU power, it often still completes faster than other codecs which do utilize my cores. What I'm trying to say is that CPU usage and transcode time do not have a linear relationship.


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Michael Phillips
Re: Is the DNxHD codec mis-designed?
on Jul 12, 2012 at 6:13:27 pm

Did this developer license the optimized DNxHD codecs from Avid or are they using the free download version? These are different in performance. I do know that in a dailies creation program, targeting native MXF wrapped DNxHD, all 24 cores were firing away at near capacity and I was getting 2x faster than real time with LUT and color correction applied.

Michael

Michael Phillips


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