OpenCL GPU support in svn5466

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Mihai83
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Joined: Sat Jul 13, 2013 7:59 am

OpenCL GPU support in svn5466

Post by Mihai83 »

Hello,

As the title says, i have a problem with my HandBrake-svn5466_x86_64-Win_GUI, i can't enable opencl on GPU and encodings are by default on CPU which takes a lot of time (5FPS on slow preset when transcoding from 1080p to 720p) and it's not good.My CPU is Quad Core Amd Athlon 2 x4 @ 2.6 Ghz and my GPU is Sapphire RadeonHD5750 @ 700 Mhz Juniper GPU.I am running windows 7 Ultimate x64 SP1 with the latest Catalyst beta drivers 13.6 from AMD and of course, the latest APP SDK.However, for some reason, my GPU is not recognized by handbrake.At this point, i really don't know what to do and i am wondering if my hardware is supported by handbrake. So please pretty please, help a noob out, if you can.Thank you! :(
Smithcraft
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Re: OpenCL GPU support in svn5466

Post by Smithcraft »

Perhaps you could post a log(see the instructions in the red box above your post) so we could see what's going on?

SC
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s55
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Re: OpenCL GPU support in svn5466

Post by s55 »

Don't bother with the OpenCL Build, it's got too many major problems.

The current nigthlies have the x264 lookahead acceleration, but you'll probably not get any benefit from it with the settings your using. When I initially tested it, it only really seemed to benifit low lookahead values (~10) on slower systems.
Mihai83
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Re: OpenCL GPU support in svn5466

Post by Mihai83 »

http://pastebin.com/inVCS1Sh

This is my log...i highly doubt it's actually using the GPU power, although it says so...5 FPS is way too slow...perhaps i'm doing something wrong and i'm messing up the settings and that's why it's taking so long? I don't even have a big monitor, that's why i want 720p videos instead of 1080p.With another program (Rovi Total Code Studio) i have 30-37 FPS with OpenCL enabled, but the output video always turns green, i have no ideea why...and...without openCL it runs at 10-15 FPS and the result is fine. Anyway, can someone please recommend me a handbrake nightly with opencl and could you please tell me how to enable acceleration? I am a bit confused, in the wiki it says
x264: build with OpenCL lookahead support by default.

The necessary headers are included in the x264 source, so the only new dependency is perl.

The OpenCL-accelerated lookahead is disabled by default and can be enabled at runtime using the "opencl" advanced x264 option.
at the runtime?!? which runtime, where do i find it?


Thank you for your answers! :D
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s55
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Re: OpenCL GPU support in svn5466

Post by s55 »

From the logs, it looks like the acceleration is infact working. It's just slower.

Your system is far from optimal in terms of hardware to get any kind of benefit out of OpenCL.
The current OpenCL builds are extremely heavy on memory heavy and your GPU just doesn't have the bandwidth to process the data in/out fast enough so it'll be a major bottleneck. AMD is hopefully going to provide patches to improve this somewhat in the future but it's probably not going to help for older hardware like this. Anything less than a mid-range 7000 series part isn't going to cut it. Even then, the "improvements" opencl brings are pretty small.

Basically, forget OpenCL.
Mihai83
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Re: OpenCL GPU support in svn5466

Post by Mihai83 »

Ok, thanks...at the right time, i will upgrade to a haswell + GTX 660 and i will use quicksync and/or cuda.
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s55
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Re: OpenCL GPU support in svn5466

Post by s55 »

CUDA isn't very usable. Quality isn't very good. I think some of their newer cards actually have dedicated encoder hardware now instead (a bit like quicksync) but I don't know of any software taking advantage of it.
QuickSync is the only promising acceleration option at the moment, and even then it's not great in terms of quality or speed (although it's getting better with haswell) and it's certainly usable. I see people more using it for encodes where quality isn't the most important factor and still using x264 for archival.
Mihai83
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Re: OpenCL GPU support in svn5466

Post by Mihai83 »

Ok, so you're saying i should probably choose an AMD gpu instead of nvidia.Thanks for the tip. :)
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s55
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Re: OpenCL GPU support in svn5466

Post by s55 »

I didn't say that. AMD's encoder solution is just as terrible. OpenCL has potential on both Nvidia and AMD cards but it's still early days and so far the hype has far ourweighed the results.

Basically, go do some research before purchasing.

And fwiw, I think there's actually a 760 card now to replace the 660. Probably not much difference though.
Mihai83
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Re: OpenCL GPU support in svn5466

Post by Mihai83 »

Thank you.I will surely choose the suitable hardware at that time, who knows what the future holds anyway? ;)
AAT
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Re: OpenCL GPU support in svn5466

Post by AAT »

But there were improvements using OpenCL acceleration, especially combining with AMD's UVD acceleration. According to my last test run https://forum.handbrak ... 39#p124739, I've measured more than a minute difference than without turning the features on. And that 5418 #5 build still did not contained the lookahead patch. Unfortunately I do not have access anymore for these beta builds to test them... :(
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Rodeo
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Re: OpenCL GPU support in svn5466

Post by Rodeo »

It was discovered that the downscaling algorithm used was not the same (bicubic via OpenCL, lanczos via CPU), and switching the CPU path to use the same algorithm as the OpenCL path made the CPU path faster than the OpenCL one in most cases.
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s55
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Re: OpenCL GPU support in svn5466

Post by s55 »

To add to that, it short circuited the process so the filtering and scaling wasn't working correctly.

The patch is sitting in a rejected state right now. Someone from AMD did say they were going to try and fix it but I haven't heard back from them in a while.
AAT
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Re: OpenCL GPU support in svn5466

Post by AAT »

Ok, thanks for the updates. Then look like ain't worth to wait more for these accelerated versions, OpenCL is nothing, Quiksinc cause quality loose (for me even slowed things down). How about the AMD's UVD accelerator, is that also just a algorithm change trick?
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s55
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Re: OpenCL GPU support in svn5466

Post by s55 »

UVD is potentially beneficial if it's wired up properly, bust mostly only for slower machines. The hardware in the current generation is designed for playback and I've found it tops much lower than what a high end system can encode at.

If the guys at AMD get back to us with a new patch, the OpenCL code has the *potential* to provide a small benifit but it's all up in the air. We just can't accept the patch in the current form as it's broken stuff.
Mihai83
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Re: OpenCL GPU support in svn5466

Post by Mihai83 »

Interersting...so, if AMD patches opencl properly, there will be speed improvements, even for slower machines? :D
honestly, at this point, even a constant 20 FPS encoding speed would be great for me.
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