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Subject: Re: [OMPI users] Open MPI instructional videos
From: Adrian Knoth (adi_at_[hidden])
Date: 2008-06-04 06:13:42


On Wed, Jun 04, 2008 at 11:19:48AM +0200, Adrian Knoth wrote:

> People usually recommend ffmpegX for OSX. You might give it a whirl to
> transcode your mov to something else, let's say H.264 in an AVI
> container. (MP4/AVC, DivX, xvid, there are so many names for it)

I've checked your files, they're quite good. They are already H.264 and
AAC (advanced audio coding), the only thing wrong is the mov container.

It's easy to repack this to avi:

   $ mencoder input.mov -ovc copy -oac copy -o output.avi

I've tested it with openib-btl-tuning:

adi_at_chopin:/tmp$ ls -l openib-btl-tuning-v1.2.mov
-rw-r--r-- 1 adi adi 16249094 Jun 4 11:24 openib-btl-tuning-v1.2.mov

adi_at_chopin:/tmp$ ls -l ompi-test.avi
-rw-r--r-- 1 adi adi 15964104 Jun 4 11:26 ompi-test.avi

(you can download it here: <http://adi.loris.tv/ompi-test.avi>)

On the other hand, the files are way too large. The video doesn't
contain much inter-frame correlation, so it's a good idea to give the
encoder some hints:

adi_at_chopin:/tmp$ ls -l test*.avi
-rw-r--r-- 1 adi adi 36171648 Jun 4 11:47 test.avi
-rw-r--r-- 1 adi adi 35323842 Jun 4 11:58 testx264.avi

(from approx. 160MB to 35MB). The first one is MPEG4 with an MP3 audio
stream, the second is H.264. Both video encoders were forced to 100kbit/s
and keyframes every 300 frames (not for x264):

   $ mencoder input.mov -oac mp3lame -ovc lavc -lavcopts \
         vbitrate=100:keyint=300 -o output.avi

For testing purposes, try http://adi.loris.tv/ompi-optimized.avi

I'd like to hear if these files, especially the last one, are working for
other users.

If so, I'd take care to convert the movs to avi, probably MPEG4.

(in that case: Jeff, you could probably give me all files in an archive
or point to a direct download link, so I don't have to click through the
website but just fire up the encoder in the for loop)

-- 
Cluster and Metacomputing Working Group
Friedrich-Schiller-Universität Jena, Germany
private: http://adi.thur.de