Parallel processing with OGG corruption
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#159 Parallel processing with OGG corruption
closed
1
2017-08-17
2017-03-22
No
Hello, a similar bug to #86 reported in late 2014 occured to me today in the latest snapshot (20170317), instead while converting various FLAC and MP3 to OGG with parallel processing enabled. All of the files had garbled or glitched audio, were inaccesible or had other inconsistencies. Converting with parallel processing off works just as it should. I am running this on Archlinux 64 with 4 threads.
Discussion
Anonymous
Hi, I tried to reproduce this, but couldn't find any issues. Ogg Vorbis files come out fine here no matter if I use parallel processing or not.
Do you use the official build from freac.org / SourceForge? Or a package provided by your distribution?
What Vorbis encoder settings did you use? I tried with the default, VBR 6.0.
I installed the snapshot from the AUR which builds it directly from . I used VBR 8.0. and I will try to recreate the scenario this afternoon, just to make sure. I am certain there is an issue though, as the vorbis encoder is hard to misconfigure. The transcoding went well on the same settings with parallel off.
Last edit: Johann Hackl 2017-03-22
OK, I think I've found the cause of this. fre:ac supports several different MP3 decoders, mpg123, MAD and LAME and it turns out the LAME decoder is not thread safe.
You probably do not have the mpg123 or MAD decoder on your system, so fre:ac falls back to using LAME. I was not aware of the LAME decoder not being thread safe, so fre:ac does not take any precautions when using that decoder. The LAME encoder is perfectly thread safe after all...
So, to fix this issue on your system, please install the mpg123 (preferred) or the libmad package. fre:ac should then automatically use that decoder.
In the next release, I will mark the LAME decoder as non thread safe to prevent this bug. I will also contact the maintainer of the fre:ac AUR package and ask him to add mpg123 or libmad as a dependency.
That seems to have fixed it, freac is now decoding with mpg123 as active decoder. Thank you for your work!
Great! I'll close this ticket two weeks after the next release is out.
Closing this ticket now as a snapshot with a fix has been available for more than two weeks.