Multithreaded Mencoder Crash & Encoding Help

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Zerolapse
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Multithreaded Mencoder Crash & Encoding Help

Unread postby Zerolapse » Mon Jun 15, 2009 8:23 pm

I've been doing some captures with my new Octane Compression board (thanks recondas!) using the following command from Ian's howto (thanks also to Ian):

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dmrecord -p video,device=impact,comp=jpeg,engine=impact,brate=30000000 -p audio,channels=2


That worked great...although I get some pretty hefty video from it. :-) So I decided to try and convert it down to something more portable using mencoder, but if I try and use more than one thread it crashes with a bus error. I'm trying with the following command:

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mencoder ./test.mov -oac lavc -ovc lavc -lavcopts threads=2 -o test.avi


Is this a known issue? I couldn't find anything in the forums about it.

I've also tried using ffmpeg but I get some nasty video artifacts (a bar in the middle of the screen) where it was presumably stitched together...if I use a single thread it works fine. Also using 3 threads produces 2 bars, etc,etc. I used this command for ffmpeg:

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ffmpeg -i ./file.mov -s 720x496 -mbd rd -flags +4mv+aic -trellis 2 -cmp 2 -subcmp 2 -g 300 -pass 1/2 -threads 2  file.mpg


dmconvert also seems to be single threaded only....

Anyone have any ideas on this? I'd love to be able to do some multithreaded encoding with a decent result so I can make use of some Origin muscle for encoding. :-) If anyone has any other recommendations I'm open to those as well.

Thanks!
-Jesse
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hamei
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Re: Multithreaded Mencoder Crash & Encoding Help

Unread postby hamei » Mon Jun 15, 2009 8:55 pm

Zerolapse wrote: If anyone has any other recommendations I'm open to those as well.

This looks interesting to me

http://mplayerxp.sourceforge.net/

There's also some stuff about a newer multi-threaded ffmpeg on the normal mplayer page ...

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Re: Multithreaded Mencoder Crash & Encoding Help

Unread postby Zerolapse » Mon Jun 15, 2009 8:59 pm

Hmm...I wonder if it's worth trying to get them running on IRIX.
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bri3d
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Re: Multithreaded Mencoder Crash & Encoding Help

Unread postby bri3d » Mon Jun 15, 2009 9:01 pm

Alternatively you can just encode sections of the video simultaneously - that's what I do on my PCs. Just split the video into x chunks of total/x frames where x is the number of CPUs, and tell each mencoder which frames to do. If you want to get really fancy you can even pick the nearest full-screen change (that would require a full frame anyway) so you don't even lose any compression performance.

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Re: Multithreaded Mencoder Crash & Encoding Help

Unread postby Zerolapse » Mon Jun 15, 2009 9:04 pm

That's a pretty good idea....have you automated that or do you have a tricky way of splitting them up and re-attaching them?

-Jesse
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