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Ultra HD playback and beyond...

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John Straus
Ultra HD playback and beyond...
on Jun 23, 2013 at 5:15:11 am

So in a nutshell I am trying to play a very large file smoothly. It is an uncompressed 6k file that needs about 1400MB/s for smooth playback. I have a Areca 1882ix card that seems to give me the speed I need in AJA although a bit flakey in read speed varying from 2200-2800MB/s but should handle the file. I am using 8 840 Pro SSDs. The write speeds are much more even at about 2600MB/s but all I need is read. The odd part is when I play the file I get about 14fps, the goal is 24. When I monitor the drives with HD Tune while playing the file it maxes at about 750MB/s throughout playback. This might not be a raid issue but I figure I'd start here. When configuring an older player to manage a 4K uncompressed file It had to have it's ram run in dual channel or playback was flakey. Could I be running into a memory bandwidth limitation due to the file size? Also a 4K file plays back without issue with a 2 drive Raid using the onboard intel ports. The CPU and total memory it takes is very low since there is no uncompressing to do. But I was thinking the speed and or bandwidth might have something to do with the low fps. I only have 8 SSDs in there to see if it helped the fps but it does not. I am using a new Haswell i7 with an ASUS WS Motherboard. I have a 2011 x79 MB I can try with quad channel memory but it might be a few days before that happens.

Any thoughts appreciated!!

JS


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Alex Gerulaitis
Re: Ultra HD playback and beyond...
on Jun 23, 2013 at 6:27:13 am

[John Straus] " read speed varying from 2200-2800MB/s ... maxes at about 750MB/s throughout playback"

Perhaps an application issue then? What application is used for playback? What OS?

I'd try a few things:
- RAM drive (which will perhaps need a Xeon system with 64GB+ memory) - test playback. If still 14fps, then it's not a disk I/O issue.
- increase stripe and file system block size
- stripe using OS and not Areca (may need a system with more cores - i.e. dual Xeons)

Alex Gerulaitis
Systems Engineer
DV411 - Los Angeles, CA


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John Straus
Re: Ultra HD playback and beyond...
on Jun 23, 2013 at 2:23:26 pm

Hi Alex,

Media Player Classic-HC is the player. Win7 Pro is the OS. The Raid is 64 & file sys is 64 stripe block.

Thanks for the test ideas!!

John


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Paul King
Re: Ultra HD playback and beyond...
on Jun 23, 2013 at 11:25:20 pm

Hi John

Can you try compressing the file maybe 2:1 and retry.
If it plays then it's disk IO, if not then it's somewhere else.
Can WMP classic even playback 6k?

Also, is there a difference between full screen and playing back in a window.

8 x 840pro is over 4GB/sec so you have reached the limit of the Areca/LSI CPU. I know that prior to LSI buying Areca they had deeper level access to their controller BIOS. In there you could make adjustments to the way the controller dealt with streaming.
You could ask Areca and see if they'll give you access - if it still exists.

Adaptec controllers can go up to 6GB/sec and they're not too expensive if you feel like trying.



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John Straus
Re: Ultra HD playback and beyond...
on Jun 25, 2013 at 1:27:31 am

Hi Paul,

Trying not to compress. It changes the whole computer. Any compression takes a crapload of CPU. I am running a 6 core Xeon 3.3 and it can handle a 5K file but chokes on 6K in ProRes... When running MPC-HC with an uncompressed file window size seems not to matter. When running the same file in ProRes in QT window size matters.

The playback should not take the 8 SSDs I have installed. I just did that to see if it actually made a difference. I started with 4 adding 2 at a time. Still got the 750MB ceiling.


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Paul King
Re: Ultra HD playback and beyond...
on Jun 26, 2013 at 9:45:15 am

Hi John

2:1 is not as compressed as Prores. Maybe try a loss-less CODEC if you can. The alternative is the Adaptec controller I mentioned, which is not expensive, unless it turns out not to be drives.

The other suggestion mentioned was the RAM disk which is a cheap way to check it's not a drive issue.

Also, what GFX card do you have and how much RAM does it have?



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Antoine Durr
Re: Ultra HD playback and beyond...
on Jul 9, 2013 at 6:01:46 am

Graphics card and/or playback software would be my guess. With 8 840 Pro's you've got plenty of bandwidth. However, it being Windows, you could theoretically run into a fragmentation issue, and though the SSD's will mitigate most of that, it might be the difference between realtime and not realtime. However, if your frame rate is solid (albeit low), then most likely it's not an issue of patterns on disk. The playback software has to read the file, decode it, send it to the graphics card, which then has to scale it down so that you can see the entire image on your monitor/projector. Try different playback software, e.g. something like Resolve or Scratch. Try transcoding the sequence to a different, more native, format. For grins, try converting the frames to jpg and see what you get that way. Try a different graphics card, esp. one of the newer ones that are designed to play back 4k or UHD, e.g. K5000, Radeon 7950.


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