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4K Playback Headroom


Sound Bites LLC
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Hi All,

 

So yesterday, Steve Farris and I tested some 4K playback on 2 different systems. One was a new Mac Pro w/ the Quad Core 3.7GHz Xeon w/ D300 GPU's and the other was my machine with an AMD FX-9590 @4.7GHz w/ a FirePro W9100. Both of these offer similar performance in the CPU department. Both machines are running Windows 8.1 Pro 64 Bit, fully updated. SSD's in both systems. Plenty of RAM. We only tested 2x 4K screens per machine since that's all that was available.

 

These videos had the following basic parameters:

 

3840x2160 pixels

H.264

24 or 29.97 FPS (depended on the individual video)

Variable Bitrate that swings between 15-33Mbps

 

Using VLC to play 4K videos, each machine could play 6x 4K videos using between 85-92% of the CPU on average. In Watchout 5.5.2, only 3 streams of any of these would play smoothly. Adding a 4th would peg the CPU. 2 of these 4K videos used approximately 60-65% CPU when using Watchout. The same vids played in VLC only used 25-28% CPU. It made no difference if the vids were full screen or windowed in VLC or full screen or scaled in Watchout.

 

Is this just due to CODEC issues? VLC is not configured to offload any decoding to the GPU. VLC was also not installed, but in a standalone folder using the portable version. No CODEC packs were installed on the systems.

 

Any ideas?

 

EDIT: I'm going to add to this that I tested these same videos in QuickTime and it couldn't play 2 of these videos at the same time smoothly. They paused randomly, and stuttered. The CPU hovered between 40-50%.

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If you want to play a large number of 4k videos, you'll get better performance using MPEG2 insted of H264 simply because that codec isn't as heavy. GIven enough bitrate (which typically isn't a problem in WATCHOUT), MPEG2 often looks just as good. The best/only way I found to encode 4k MPEG2 is ffmpeg, which is command line based and availble for all OSes. There are lots of tutorials on how to use it for encoding various formats.

 

FYI, WATCHOUT 6 includes support for a number of new video codecs and formats, which will improve this situation further. For example, the HAP codec allows you to play several videos without overloading the CPU (but has a very high data rate, so you need a fast SSD and I/O subsystem to acommodate the data).

 

Mike

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Thanks for the response and the advice, Mike. I'll give a shot at re-encoding the videos and see how it goes with ffmpeg. It's cool regarding the support for the HAP codec. Looking forward to seeing Watchout 6 in action.

 

What I'm really curious about though is why does Watchout 5.x use up so much more CPU to play the same videos? Any thoughts on that?

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