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Video Encoding with OpenCL on Mavericks

J

jeffmetanna

macrumors member
Original poster
Apr 16, 2010
76
110
Now that OpenCL is baked into the Mavericks, where are we with the OpenCL-based video encoders? Anybody in the know?

Also, how about QuickTimes? Has anybody tried converting videos with QT on Mavericks?

Lastly, the Intel QuickSync... Are we ever gonna see this running on OS X?

Let's move forward with the technology people!!
 
OpenCL is still useless for video encoder. You can do a h.264 encoder in OpenCL, but it will be slower than a cpu one.

QuickSync was already in 10.8, QuickTime uses it for decoding and encoding. In 10.9 there is a public api to use the encoder too. Unfortunately there aren't many encoding settings, and you can always get better quality and speed from x264 on the cpu. QuickSync is nice if you want to stream for example your screen to an AppleTV. I wouldn't use it to encode video files for delivery.
 
It'd be nice if you could utilize CPU + GPU at the same time. I know FCP X uses GPU accelerated rendering as sometimes my CPU usage drops to nothing and the video keeps rendering out fast during segments with allot of effects. I'd like to see the GPU as sort of another processor so my quad core CPU can spread its workload to the GPU, although I'm not so sure parallel processing works like that at all.
 
Does anybody know if the standard "export to 720p/1080P" presets in quicktime x on mavericks use quicksync (and are 1pass encodes) or if those are software based encodes? Quality and speed of those encodings are really stunning (especially speed) on my late 2012 imac.

I've ordered a nMP though and am wondering if I will suffer from a xeon speed penalty since it doesn't have quicksync on board?:confused:

Example: I encoded a 2:30 video.
Quicktime: 30 seconds
Adobe Media Encoder 1pass: 1:40
AME 2 pass: 3:00

how can it be THIS much faster and look so good? even better than media encoder 2 pass I would say!
 
Last edited:
chfilm said:
Does anybody know if the standard "export to 720p/1080P" presets in quicktime x on mavericks use quicksync (and are 1pass encodes) or if those are software based encodes? Quality and speed of those encodings are really stunning (especially speed) on my late 2012 imac.

I've ordered a nMP though and am wondering if I will suffer from a xeon speed penalty since it doesn't have quicksync on board?:confused:

Example: I encoded a 2:30 video.
Quicktime: 30 seconds
Adobe Media Encoder 1pass: 1:40
AME 2 pass: 3:00

how can it be THIS much faster and look so good? even better than media encoder 2 pass I would say!
Click to expand...

im kinda wondering about some of my times also maybe we could share raw footage so we could do some render time comparisons?
 
Sure, maybe we can find something out. I'm uploading a 2 GB prores HQ video and will post it soon.
 
Ritsuka said:
OpenCL is still useless for video encoder. You can do a h.264 encoder in OpenCL, but it will be slower than a cpu one.
Click to expand...

I would not say that. FCP X uses OpenCL for export and I rendered a video file in 1:30 while the same file in Compressor 4.1 took 6 minutes.
 
There you go, some footage from a film I made 2 years ago:

http://chfilm.de/download/h264/h264_bench.mov

My results, performed on a Late 2012 imac 3,4 Ghz i7, 32GB Ram GTX 680 MX
(internal HDD to pegasus R6)



Quicktime X 1080p preset:
18,5 sec

Adobe Media Encoder CC (using cuda or open cl acceleration, in makes almost no difference for me) @1080p Apple ipad 2,3,4, atv3 preset with a vbr of 9,5mbit to match quicktime:

1 pass: 1:48

2 pass: 2:09

2 pass using only software acceleration: 2:07

Compressor with 1080 HD sharing services preset
5:40

Handbrake
Normal Profile, average bitrate 9500, 1pass
0:49

High Profile, average bitrate 9500, 2pass, turbo first pass
3:01

Final Cut X 10.1.1
1080p apple devices fast export:
0:25

1080p apple devices high quality export
6:31



Some strange results there! Final cut and Quicktime X didn't even push the CPUs to the limits, not even close actually. Still they were the fastest in single pass export.
This HAS to be due to quicksync technology, there's no other explanation to me.
So quicktime X does indeed single pass encoding.

Still I wonder why the quality is just so good. People might be right, it's not for absolute final delivery, but you COULD use it, as it absolutely looks really well.

I'm a bit sad about giving away my beloved imac for the nmp, seeing those digits.
I really hope my new toy can at least be on par with the imac in single pass encoding even without QS.

Honestly the differences I got - quality wise - between single and dual pass encodes were so tiny.. I don't see a point in wasting so much more time for MOST cases by far!

----------

And can someone please tell me what's going on with Adobe Media Encoder 1 pass encoding? Why is this so slow? Where's quicksync here?:confused:
 
I wonder in what preset, since with the standard "1080p sharing for devices" preset which sounds the same as the QuickTime option to me, it was obviously either 2pass or without quick sync!
 
You know, you can configure HandBrake to be faster than QuickSync and have a better output quality. The only advantages of QuickSync is that it doesn't use the cpu.

HandBrake nightly builds has got QuickSync support, but it's windows only right now.
 
northernmunky said:
The new Compressor 4.1 uses Quicksync
Click to expand...

Does it only use QuickSync when doing a single pass? And to all formats or just h.264?

While doing a high quality two pass DVD encode it looks like it's just using 100% CPU. The iGPU is just idling along at 350mhz (it's lowest setting on a MBA with i5-3427U) while the CPU is pegged at 2.60Ghz. (I believe the fastest boost clock when using both cores on this MBA... or maybe Apple just limited the boost of the i5-3427U to 2.6Ghz instead of Intel's standard 2.8Ghz... I've NEVER seen it boost to that)
 
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