H264 single pass - job segmentation not available

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H264 single pass - job segmentation not available

Hello,

Compressor is one of our main tools for coverting movies for our customers. Normally we convert to simple H264-files. On our Dual-6-Core MacPro with 20GB RAM, using multiple instances, single-pass encoding, it's done in 0.5x Realtime.

Since version 4.2 the option for job segmentation is not available anymore. I can't activate it.

Only when I switch to multi-pass H264 encoding it is available again.

Without job segmentation or multi-pass and job segmentation we need way more than realtime. This is not acceptable.

So, is it a bug? Or am I doing something wrong?

All our other settings are still working, just our H264-Settings with single-pass encoding are broken.

Thank you,

Doyle

Mac Pro, OS X Yosemite (10.10.3), Mid 2010, 2x6Core, 20GB RAM

Posted on Jul 8, 2015 7:13 AM

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Answer 1

BenB

Level 6

12,097 points

Jul 8, 2015 8:30 PM in response to doyle138

OK, so you're working with a single computer, so "job segmenting" is pretty much a non-issue, ignore it. That only really allows jobs to be shared out over a network between Macs, for very large transcodes.

http://help.apple.com/compressor/mac/4.1/#cpsrf4de2b70

http://help.apple.com/compressor/mac/4.1/#cpsr4748621f

"Multiple Instances" is something different, and internal to your Mac using multiple CPU/GPU units.

http://help.apple.com/compressor/mac/4.1/#cpsrd42eb6d3

Two different functions, two different settings.

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Answer 2

doyle138 Author

Level 1

0 points

Jul 9, 2015 2:24 AM in response to BenB

Hi,

thank you for your answer, but I think you are wrong.

We always used job segmentation for our settings because only then the file will be splittet to all of our 24 CPU cores.

Without segmentation the CPU only works with 1-2 cores.

In the settings you define how compressor will distribute the transcode job, over network or local on your CPU/GPU. To use this setting for a job, you activate the segmentation. For small jobs you don't need to activate it because you have no advantage from splitting small jobs.

You have to activate both, instances and job segmentation to allow compressor splitting a file to all your cores. This is how we work for years.

For example: I transcode a file to DVD, all instances activated, no job segmentation. In the job monitor the file will not be splitted, 8 minutes transcoding on 1-2 Cores.

When I activate job segmentation for the same transcode, the file will be splittet to 10 parts, 2 minutes transcode time, als Cores are working to maximum.

But the segmentation works fine for all of our settings except H264 single-pass and that is the problem. Just this setting and this is new, we never had this problem with an older version. Only multi-pass allows the segmentation but multiple passes are not necessary and need to much time.

Doyle

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Answer 3

Russ H

Level 7

22,432 points

Jul 9, 2015 4:47 AM in response to doyle138

One would think that with up to 5 instances of Compressor available to your MP, it would scream through these h.264 jobs.

But the real world answer is complicated and seems that each of the recent releases of the software produces a lot of interesting and unexpected results – varying with the type of hardware, configuration, and codec. Larry Jordan's recent testing seems to support your observations. (Check the longer encode times he got for multiple instances on a Mac Pro in his table.)

Russ

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Answer 4

Russ H

Level 7

22,432 points

Jul 9, 2015 9:15 AM in response to doyle138

As a follow-up, I ran a quick test this morning on a 6 core MP and found that for a single pass H.264 encode, 2 additional instances took about 5% longer to complete than enabling no additional instances, (In other words, it was slightly faster not to add the additional instances of Compressor.)

Russ

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Answer 5

doyle138 Author

Level 1

0 points

Jul 9, 2015 9:31 AM in response to Russ H

I also did a quick test this afternoon and got the same results. All 5 instances single-pass transcoded longer than 1, or even without the instances option. This is new for me and it is a bit annoying.

For all my other settings I still get the best results with all 5 instances and job segmentation, just H264 single-pass gets better results without using instances.

So with this version I have to double check before setting up my job lists and I have to separate the H264 jobs from the other jobs because now I have to deactivate the instances at first. Or I have to deal with slightly more transcode time for this files.

Thank you all for help and tips.

Doyle

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