[parsec-users] Artifacts in x264 encoded video.

Benjamin Havey benhavey at gmail.com
Fri Nov 1 11:47:22 EDT 2013


Hey there,

So I'm doing research using the Parsec 3 test bench. I decided to check out
the output of x264. I ran x264 the following way:
./parsecmgmt -a run -c gcc-hooks -i native -n 8 -p x264

The resulting file has lots of artifacts and is very low quality/choppy.
Another thing to note is that the kb/s metric spikes to about 60,000 for 1
thread while it stays around 30,000 for every other # of threads.

Here's the weird thing: I tried running x264 using Parsec 2.1 and had
different results. The output file from parsec 2.1 was clean with no
artifacts. I ran them both with the same input file and the encoding
settings are the same.

I've tried rebuilding x264 and have also tried different thread/simulation
size combinations and the resulting videos always come out the same.

I'm running this on an Ubuntu 12.04 virtual machine with 8x Xeon E5-2603
CPUs and 32Gb of ram.

Any insight would be greatly appreciated.

Thank you,
Ben
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