Sandy Bridge - Quick sync

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Big Roo
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Joined: Fri Mar 25, 2011 9:55 am

Sandy Bridge - Quick sync

Post by Big Roo »

Hey guys,

Quick question.

If i upgrade my computer to the new sandy bridge CPU i7 2600, does that mean that quick sync will take over the encoding that handbrake does. I was just reading on a forum in Australia that someone is looking to use this new CPU because it flies though encoding at much faster FPS than current cpu. But someone mentioned how quick sync does the encoding and that it may not do as good of a job as say what handbrake does.
Im a bit lost on it though. If i used handbrake then how would quick sync do the work?

Thanks
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JohnAStebbins
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Re: Sandy Bridge - Quick sync

Post by JohnAStebbins »

HandBrake does not use quick sync. And quick sync has no magic way of detecting when some program is encoding video and stealing control from it.
Big Roo
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Re: Sandy Bridge - Quick sync

Post by Big Roo »

Hi John,

yes that had me confused.
this is what someone wrote about it in the forum i was reading.
"It's (quick sync) a dedicated device on Sandy Bridge silicon that does h264 encoding *instead* of any other encoder you'd use, like x264."
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JohnAStebbins
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Re: Sandy Bridge - Quick sync

Post by JohnAStebbins »

Poor wording. If you are using x264, then x264 would have to be aware of quick sync and making calls to it in order for quick sync to be used. The "instead" probably was in reference to some other piece of software besides x264 that would make use of the quick sync hardware.
Big Roo
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Re: Sandy Bridge - Quick sync

Post by Big Roo »

ok cool thanks John.

what sort of cpu do you use out of interest?
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JohnAStebbins
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Re: Sandy Bridge - Quick sync

Post by JohnAStebbins »

2 quad core nehalem xeons. There are faster options now. If money were no object, I'd be looking for a fast hex core nehalem or wait for the hex core Sandy Bridge-E.
Big Roo
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Re: Sandy Bridge - Quick sync

Post by Big Roo »

wow ok. what sort of fps do you get at standard settings when working on a large mkv file taken from a bluray disc for example?
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JohnAStebbins
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Re: Sandy Bridge - Quick sync

Post by JohnAStebbins »

What's standard? I use a preset that is fairly close to the high profile preset but has detelecine and decomb turned off for blureray content. I get around 18fps on blueray material.
Big Roo
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Joined: Fri Mar 25, 2011 9:55 am

Re: Sandy Bridge - Quick sync

Post by Big Roo »

well i mean if you put a 20GB mkv file into it, then leave everything on default under normal preset with say DTS passthru and Target size say 15000MB.

i tried this on friends i7 2600 and it was running around 60-70fps on 8 threads
thompson
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Re: Sandy Bridge - Quick sync

Post by thompson »

Big Roo wrote:well i mean if you put a 20GB mkv file into it, then leave everything on default under normal preset with say DTS passthru and Target size say 15000MB.

i tried this on friends i7 2600 and it was running around 60-70fps on 8 threads
I doubt he'd be using Target File Size, as that option is both the Worst Way To Encode and, for that reason, has been removed from Handbrake after 0.9.5.
Big Roo
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Re: Sandy Bridge - Quick sync

Post by Big Roo »

thompson wrote:I doubt he'd be using Target File Size, as that option is both the Worst Way To Encode and, for that reason, has been removed from Handbrake after 0.9.5.
well ive used it and i dont see much of a difference. why is it the worst? what does it do for you?
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JohnAStebbins
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Re: Sandy Bridge - Quick sync

Post by JohnAStebbins »

well ive used it and i dont see much of a difference. why is it the worst? what does it do for you?
Target file size only has one purpose which is to meet a requested file size. And it often failed to do that. Target file size is the same thing as Average BitRate encoding. HandBrake was just computing the bitrate for you.

If your primary concern is getting the best quality vs. size trade-off, ABR encoding sucks balls. The bitrate required to achieve a certain quality differs widely from source to source. So if you are using the same ABR all the time, some sources will be lower quality than others. Pick the lowest quality of all those that you encoded with ABR; if you were satisfied with that quality, then you should have made *all* your videos that quality (which would have required lower bitrate for *all* the rest of your videos). If you were not satisfied with the quality, then you should have used a higher bitrate. Constant quality encoding makes all these decisions for you. All you have to do is pick the RF value that gives the quality that you are happy with and it will customize the bitrate for every source to meet your quality objective.
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