Good PC for x264 encoding

[xandercage]

I need pc for x264 encoding from full Blu-ray Discs to x264 mkvs.

How many cores, memory, threads are a good solution?

6core cpu or some dualsocket mobo with xenons?

Something what I can overclock?

How many threads x264 support. In newest megui I can see only 16 but some encodes have 24 in settisgs???
So can someone explain how it works?

Dont care about prize :)) but yes 5000 Euros should be max.

Thanks

[mp3dom]

I think your "best" highly depends by the settings/quality/speed you want. With an i7 920, 6 GB Ram DDR3 and 12 threads [(8*3)/2] and x264 settings maxed out (subme=10, me=tesa, profile 'placebo') I have about 0.8fps on a 1080p24 source. If I reduce subme=9, me=umh and profile "veryslow" the fps jumps to nearly 1.6fps (in every case the speed depends by the complexity of each scene). If you want 'realtime' with huge settings, probably even the highest rank pc isn't enough.

[xandercage]

I prefer quality about speed. Acceptable time for encode is about 3-5 days. If I can use better settings no problem :)), if encode is done durring 5 days. average encode has about 180000 frames.
All my encodes are 1080p.

[Firebird]

Dual i7 Xeons are the best choice, I suppose.

[mariush]

You can go crazy with a quad socket 1207 board (300-500$) , 4 x quad 2.8 ghz amd 8xxx series ( ~ 1600$ each) , 4 x 4 GB DDR2 ECC Registered (116$ each), a suitable case (200$), 1 or 2 750-1000 power supplies (500$), 4 hard drives in raid 5 (about 300$).... and you have a sweet machine for about 8000 dollars which is pretty close to your 5000 euro.

or you ca go the intel dual cpu route for about 2000$

[a4840639]

Have anyone tested how much is the improvement of Hyper-Threading for encoding?(For example turn off it in BIOS and encode the same clip)
I have a i5 and I really want to know it.

[stax76]

You don't prefer quality otherwise you would buy 4 hard drives instead of 4 CPU...

[poisondeathray]

Have anyone tested how much is the improvement of Hyper-Threading for encoding?(For example turn off it in BIOS and encode the same clip)
I have a i5 and I really want to know it.


Impossible to say definitively, because there are so many factors: it depends on the source (e.g. dimensions), decoder speed/source filters, encoding settings. Anything can become the bottleneck potentially , eg. --b-adapt 2 which isn't fully multithreaded

In general, on HD sources, I've noticed in the absence of bottlenecks / filters etc.. (ie. a straight encode), HT tends to lower 1st pass performance by anywhere from 10-20% , but increase 2nd pass (or crf) performance by anywhere from 10-40%. Overall it's definitely faster. I think the lower 1st pass performance is from the lower quality settings by default. If you did --slow-firstpass it would be the same improvement as the actual encode run

[ajp_anton]

You say acceptable encoding time is 3-5 days.
You also say average encode has 180000 frames.

180000 frames in 3-5 days = 0.4-0.7 fps (<- this is your "requirement").

Your first answer said an i7 920 with maxed settings (placebo) on 1080p does 0.8 fps. This not enough?

[poisondeathray]

You don't prefer quality otherwise you would buy 4 hard drives instead of 4 CPU...

I agree 100%. HDD are way more affordable these days.

[xandercage]

You say acceptable encoding time is 3-5 days.
You also say average encode has 180000 frames.

180000 frames in 3-5 days = 0.4-0.7 fps (<- this is your "requirement").

Your first answer said an i7 920 with maxed settings (placebo) on 1080p does 0.8 fps. This not enough?

No no. Becose 3-5 days is limit. If I can use this high settings and can do it faster, so it is better.

I guess with 5000 euro PC I can do it in 1 or 2 days with this high settins?

So the question is what kind of pc can do it?

[mariush]

You know, you could actually split the source in two - three parts and use two - three systems to encode the stream and in the end you can combine the separate streams into one.

You can build systems that costs 5000 euro, but that doesn't mean its performance would be twice the performance of a 2500$ system.

So you have three options...
You can build a system that uses the latest i7 processor (for example i7 975 Extreme at 3.33 Ghz for 969$), use water cooling and overclock it so that you have for example at 4 Ghz and the system would probably cost you 2000$
Or, you could build a system that has a two socket motherboard (which costs a bit more than usual) and two quad core processors (for example Xeon W3550 Bloomfield 3.066GHz at 599$ each) and you'll need to buy a bit more expensive memory (for servers, registered memory with error correction) and you'll need a bit more special computer case for it - let's say in the end you pay 3000$ for it.

So you have 4 cores + 4 virtual cores @ (maybe)4 Ghz for 2000$ or you have 2 x 4 cores + 2 x 4 virtual cores @ 3.33 Ghz for 3000$ and my guess is that the second system would be 15-30% faster than the i7, maybe a bit more. I don't think hyperthreading (the virtual cores) would help much. Is it worth it to you to pay 1000$ more for 15-30% more performance...

But the third solution would be to get three off the shelf systems with a socket 1156 cpu (for example the i7 860 quad core with hyperthreading at 280$) and these systems would cost about 700$ each if you build them yourself. So for 2100$ you'd get 3 computers that in total would give better performance than the previous systems (and less headaches, less worries about overclocking, less energy wasted, less picking parts to be compatible) , only if you can split your encoding in three segments or if you can do three encodings in parallel.

[blubberbirne]

Try dual sockel xeon mainboard with 2 nice xeon quads (i7) :)

[Blue_MiSfit]

A single socket i7 is the best "bang for your buck" out there. There's absolutely no reason to buy anything other than the i7 920, since it overclocks so disgustingly well, and is incredibly cheap ($200 at Microcenter for me)! Pair this with a decent X58 motherboard, 6GB of RAM, Windows 7 x64, and a lot of HDD capacity, and you're totally good to go.

Otherwise, a dual socket i7 Xeon workstation / server is the fastest affordable (under $2k), and reasonable solution. Going beyond this gets very expensive :) The Xeon 5520 is the cheapest Nehalem Xeon that offers 4 cores + HT, so I suggest going this route.

Of course you can always do what my company does, and buy 50 of the latter ;) But then you have to hire 3-4 people to manage them... :)

~MiSfit

[aegisofrime]

Or you could wait till the first quantum computers :D

In all seriousness, AMD just released their 12-core server CPUs. If money is not an object those should do nicely too.

[xandercage]

You know, you could actually split the source in two - three parts and use two - three systems to encode the stream and in the end you can combine the separate streams into one.

You can build systems that costs 5000 euro, but that doesn't mean its performance would be twice the performance of a 2500$ system.

So you have three options...
You can build a system that uses the latest i7 processor (for example i7 975 Extreme at 3.33 Ghz for 969$), use water cooling and overclock it so that you have for example at 4 Ghz and the system would probably cost you 2000$
Or, you could build a system that has a two socket motherboard (which costs a bit more than usual) and two quad core processors (for example Xeon W3550 Bloomfield 3.066GHz at 599$ each) and you'll need to buy a bit more expensive memory (for servers, registered memory with error correction) and you'll need a bit more special computer case for it - let's say in the end you pay 3000$ for it.

So you have 4 cores + 4 virtual cores @ (maybe)4 Ghz for 2000$ or you have 2 x 4 cores + 2 x 4 virtual cores @ 3.33 Ghz for 3000$ and my guess is that the second system would be 15-30% faster than the i7, maybe a bit more. I don't think hyperthreading (the virtual cores) would help much. Is it worth it to you to pay 1000$ more for 15-30% more performance...

But the third solution would be to get three off the shelf systems with a socket 1156 cpu (for example the i7 860 quad core with hyperthreading at 280$) and these systems would cost about 700$ each if you build them yourself. So for 2100$ you'd get 3 computers that in total would give better performance than the previous systems (and less headaches, less worries about overclocking, less energy wasted, less picking parts to be compatible) , only if you can split your encoding in three segments or if you can do three encodings in parallel.

Idea with two or three encods in the same time is not bad.
I m now realy thinking about two dualsocet PCs.

[nm]

No no. Becose 3-5 days is limit. If I can use this high settings and can do it faster, so it is better.

I guess with 5000 euro PC I can do it in 1 or 2 days with this high settins?
Why would you want to use insane encoding settings? x264's "placebo" preset gives perhaps 5-10% better quality/bitrate than "slower" while taking 300% more CPU time. Is a <10 % difference in file sizes really that significant for you?

If I had EUR 5k to waste on a personal encoding project, I'd put 1/5 of the money on a cheap Core i7 system and invest the rest to more productive purposes, like paying some developer to make x264 5% faster or keeping the beer flowing. ;)

[Esurnir]

Why would you want to use insane encoding settings? x264's "placebo" preset gives perhaps 5-10% better quality/bitrate than "slower" while taking 300% more CPU time. Is a <10 % difference in file sizes really that significant for you?

If I had EUR 5k to waste on a personal encoding project, I'd put 1/5 of the money on a cheap Core i7 system and invest the rest to more productive purposes, like paying some developer to make x264 5% faster or keeping the beer flowing. ;)

Actually placebo give a bit less than a percentage point improvement over veryslow according to Dark Shikari

[Blue_MiSfit]

Yes. Placebo is a placebo :)

Still, in situations where you have extra CPU cycles because you're bottlenecked by AviSynth or your decoder, and only want to run one encode at once, why not use it? Not that I honestly suggest that as a real workflow. If you are bottlenecked in this way, you need to either improve the decode / filtering stage, or just run 2 encodes at once :devil:!

12 core server CPUs and other exotic hardware are not really worth discussing. As we've all said, a single i7 desktop, or a dual socket i7 workstation / server is definitely the ideal "bang for your buck" IMO.

~MiSfit

[xandercage]

Yes. Placebo is a placebo :)

Still, in situations where you have extra CPU cycles because you're bottlenecked by AviSynth or your decoder, and only want to run one encode at once, why not use it? Not that I honestly suggest that as a real workflow. If you are bottlenecked in this way, you need to either improve the decode / filtering stage, or just run 2 encodes at once :devil:!

12 core server CPUs and other exotic hardware are not really worth discussing. As we've all said, a single i7 desktop, or a dual socket i7 workstation / server is definitely the ideal "bang for your buck" IMO.

~MiSfit

What do you think about this dualsocet mobo
http://www.xbitlabs.com/news/mainboards/display/20100106094116_EVGA_Preps_Dual_Socket_Mainboard_for_Gaming_Systems.html
with two i7 980x
http://www.fudzilla.com/content/view/16828/35/

12GB memory DDR3 1066

I guess this system is about 3000$, so mabey I can get two for 5000 euro :)

It looks like I can use with this combination 36 threads for encoding, but how many threads support build x264???

[nm]

Actually placebo give a bit less than a percentage point improvement over veryslow according to Dark Shikari
Yea, sounds familiar. I got a 4 % difference (file size at the same SSIM) between placebo and slower on the last Star Trek trailer. Anime could get a bit larger gain, I guess.

It looks like I can use with this combination 36 threads for encoding, but how many threads support build x264???
You may need to do some tweaking to keep those CPUs fully saturated. The thread pool patch could help, for example. With that much memory, you can easily run multiple encodes at once though.

[mariush]

385$ 1 x http://www.newegg.com/Product/Product.aspx?Item=N82E16813131373
770$ 2 x http://www.newegg.com/Product/Product.aspx?Item=N82E16819117185
382$ 2 x http://www.newegg.com/Product/Product.aspx?Item=N82E16820148259
160$ 1 x http://www.newegg.com/Product/Product.aspx?Item=N82E16811119160
240$ 1 x http://www.newegg.com/Product/Product.aspx?Item=N82E16817139007
046$ 2 x http://www.newegg.com/Product/Product.aspx?Item=N82E16835114090
160$ 1 x http://www.newegg.com/Product/Product.aspx?Item=N82E16822136296
100$ 1 x http://www.newegg.com/Product/Product.aspx?Item=N82E16822136284

2243$

2 x 2.26 quad, 12 GB DDR3... cooler fans might be the only problem with the build above

[Blue_MiSfit]

A Dell Precision T5500 workstation or a PowerEdge R710 server will get you a dual Xeon 5520 system with at least 8GB of RAM, and a fully supported system for about that cost...

~MiSfit

[mariush]

I've been actually looking at Dell's site and tried to build a Txxx workstation using their online tools but it quickly got over 3000$... now if you're really interested (and as I understand your company buys in volume) you can get a sales agent which I believe can give you even 25% discounts on the price or a good deal.

I know that if you buy at least several systems you get your own agent with which you can talk through emails or phones and they give you quotes but for a single system I don't know what to say...

Anyway, if he's really serious about it, he should wait for AMD's 8 and 12 core chips... they're coming up in a month or so. The 8 core @ 1.7 ghz is only 260$ , with 8 core @ 1.9 ghz for about 450, and 12 core @ 2.26 ghz (I believe) at around 1600$ - of course there'll be cheaper 12 core chips at less than 1k at lower frequencies..

So you could get a 500-800$ motherboard with 4 sockets, 4 of these amd cpus at about 800$ each, 4 ddr3 modules per cpu ( they're quad channel cpus) and you have a sweet encoding machine. Imagine, 48 cores...

Two motherboards shown here... http://www.tweaktown.com/news/12395/amd_g34_motherboards_spotted_at_computex/index.html To be honest now that I look at them I don't see how you'd fit 4 sockets and all those dimm slots on a motherboard, even if it's extended atx or ssi or whatever standard rackable cases use nowadays

[Caroliano]

I'm not sure if so many threads will not significantly impact the quality of the encode. Maybe you can loss more quality than you gain going from very slow to placebo.

So far, the best sugestion is from stax76. With 5k euros you can buy 75 terabytes in HDs. This is sufficient for maybe 2k blu-ray isos, with no quality loss due transcoding. Or you can do an ~10 times faster encode that ends up with the same quality but ~20% bigger filesize, and have space for much more blu-rays.

And as already said, placebo is placebo. In some test encodes that I run on anime, it is less than 0.04db of difference compared with --preset veryslow, with --tune psnr, and more than 3 times slower. If I'm bottlenecked by avisynth, I run 2 encodes at the same time. If you don't have any encodes to do in the pipeline, you can donate your spare CPU cycles to BOINC or folding@home, or simply save a bit on your power bill.

[xandercage]

I'm not sure if so many threads will not significantly impact the quality of the encode. Maybe you can loss more quality than you gain going from very slow to placebo.

Yes this is realy good question too. How many threads can I set up for x264 encoding.
In megui I can use only 16.

Can someone confirm maximum of threads???
And is it right to many cores threds by encoding, can hurt on quality?

[kemuri-_9]

Can someone confirm maximum of threads???

libx264 has a hardcoded thread limit of 128 encoding threads.
(the lookahead thread is separate of this so there can be 129 threads overall).

[xandercage]

What do you experts think about this
http://h10010.www1.hp.com/wwpc/us/en/sm/WF06b/15351-15351-241434-241646-241477-3884315-3918544-3918545.html?jumpid=reg_R1002_USEN

With two xeons e5520 or with better xeons...., like 5550 or 5570 12GB memory.

[Blue_MiSfit]

Dell just put up the 6 core Xeon CPUs as an option for the PowerEdge R710. I'm ordering a few very soon :)

~MiSfit

[mariush]

AMD will release the 8 and 12 core processors on the 29th. Hold on a bit, maybe you'll be able to get 4 socket, 4 x 8 core cpu system cheap.

[xandercage]

I m waiting now.
What do you thing about this Workstation

Mobo
http://www.evga.com/articles/00537/

2xCPU xeon X5680
http://phonestechnology.blogspot.com/2010/02/six-core-xeon-x5680-chip-will-be-intels.html

Memory 48 GB

[mariush]

That motherboard requires special case, with 9 extension slots... Those processors will be around 900$ each...

I'm seriously thinking of getting at least a dual socket G34 + 2 x 8 core amd's... The only issue is the lower frequency and maybe the lack of some SSE functions (though I'm not sure they'd be used by x264 for example).

http://www.semiaccurate.com/static/uploads/june/Tyan_S8212.JPG

This motherboard will be 350-500$...

http://www.semiaccurate.com/static/uploads/2010/03_march/SM_4S_MC.JPG


4S Magny cours (by Supermicro)

If that isn't enough, you can step up to the H8QG6-F, a 4 socket Magny-Cours machine. It has 6G SAS, LSI SAS controllers, dual LAN and remote KVM capabilities. You also can stuff in up to 512G of ram if you don't want to bother loading from those pesky HDs. Both Magny-Cours machines use the AMD SR5690 chips or variants of it.


I think this will probably be around 600-800$... though i found it listed on a site at 1700$ bundled with a case so who knows...

The processors are cheaper... the 8 core i mean... at 300$ it's a steal... and they have only 80W tdp compared to 130w on Intel..

8-core models

* 6124 HE, 1.8GHz, 65W ACP, $529
* 6128 HE, 2.0GHz, 65W ACP, $599
* 6128, 2.0GHz, 80W ACP, $309
* 6134, 2.3GHz, 80W ACP, $599
* 6136 2.4GHz, 80W ACP, $849

12-core models

* 6164 HE, 1.7GHz, 67W ACP, $879
* 6168, 1.9GHz, 80W ACP, $849
* 6172, 2.1GHz, 80W ACP, $1,149
* 6174, 2.2GHz, 80W ACP, $1,349
* 6176 SE, 2.3GHz, 105W ACP, $1,599

http://www.semiaccurate.com/2010/02/24/us-magny-cours-pricing-revealed-early/
http://www.semiaccurate.com/2010/03/08/magny-cours-and-quad-fermi-boxes-pictured/

[kolak]

libx264 has a hardcoded thread limit of 128 encoding threads.
(the lookahead thread is separate of this so there can be 129 threads overall).

http://www.2cpu.com/contentteller.php?ct=articles&action=pages&page=118,7.html

x264 doesn't seam to scale very well on new Xeon setup with 12 cores compared to 8 one.

Andrew

[xandercage]

good qustion is with Operation system use for x264 encoding??

If I choose server motherboard wiht servers cpu s whitch OS I have to use?

[kolak]

good qustion is with Operation system use for x264 encoding??

If I choose server motherboard wiht servers cpu s whitch OS I have to use?

Does it really matter for x264?
I would go for 64bit Win 7

Andrew

[xandercage]

Does it really matter for x264?
I would go for 64bit Win 7

Andrew

Me too, but does all server mother board support 64bit win 7???

I guess no.

[orion44]

Is it true that the higher you set x264 options, it increases
compression, but then the visual quality and image detail suffer?

[orion44]

Why would you want to use insane encoding settings? x264's "placebo" preset gives perhaps 5-10% better quality/bitrate than "slower" while taking 300% more CPU time. Is a <10 % difference in file sizes really that significant for you?

If I had EUR 5k to waste on a personal encoding project, I'd put 1/5 of the money on a cheap Core i7 system and invest the rest to more productive purposes, like paying some developer to make x264 5% faster or keeping the beer flowing. ;)

I have a AMD Sempron 2800+ with 1 GB of RAM
and I'm happy with x264 default settings :)

[nm]

Is it true that the higher you set x264 options, it increases
compression, but then the visual quality and image detail suffer?
Generally no. Some parameters may have such an effect on CRF, but then you can compensate by using a lower CRF value. Slower presets will give you better quality per bitrate.

However, as you have noticed, it doesn't make much sense to use insanely slow settings for everyday encoding tasks. "Medium" and "slow" presets are quite good already and the small improvements from slowest presets come at great cost in encoding speed.

[mariush]

good qustion is with Operation system use for x264 encoding??

If I choose server motherboard wiht servers cpu s whitch OS I have to use?

Windows 7 Home Premium works with ONE cpu socket (number of cores doesn't matter).

Windows 7 Ultimate works with TWO cpu sockets.

You can use Windows 7 on server motherboards and processors but you may not find drivers for integrated audio or video or sometimes even the drive controller.

If you want Windows, it's best to use Windows 2003 or Windows 2008.

Windows 2003 feels like XP in classic mode and even accepts XP drivers.Just keep in mind Web edition works with 8GB max, Standard with 32 GB max and Enterprise with up to 2TB (though at about 2500$ who would buy it i wonder...)

Windows 2008 Standard is cheaper now, at around 400$ but I believe it has the same limitation of 32 GB of memory.

[xandercage]

Windows 7 Ultimate works with TWO cpu sockets.
You can use Windows 7 on server motherboards and processors but you may not find drivers for integrated audio or video or sometimes even the drive controller.


Yes so I would prefer intel dualsocket after all.

Mobo
http://asbis.sk/intel-s5520sc-shady-cove-workstation-board-sata-sas_d96422.html

2*CPU
http://ark.intel.com/Product.aspx?id=47916

Chassis + 1000 W PSU
http://asbis.sk/intel-sc5650ws-pilot-point-t-ws-chassis-1000w-psu_d96431.html

Can you help me with memory?
http://www.ec.kingston.com/ecom/configurator_new/modelsinfo.asp?SysID=54391&mfr=Intel&model=S5520SC+Workstation&search_type=&root=europe&LinkBack=http%3A%2F%2Fwww.kingston.com%2Fukroot&Sys=54391-Intel-S5520SC+Workstation&distributor=0&submit1=Search

GPU
GTX 8800 768MB, it is no important for encoding, and mobo suport it with 2xPCI expres 2.0 slots.


OS Windows 7 64bit Ulitmate fully compatibille with this workstation and I guess I can get driver for audio or video in this case.

Any others sugustions or Ideas?

[Forteen88]

And is it right too many cores threads by encoding, can hurt on quality?Yes, less threads = tiny better quality.

[mariush]

Yes so I would prefer intel dualsocket after all.

Mobo
http://asbis.sk/intel-s5520sc-shady-cove-workstation-board-sata-sas_d96422.html

2*CPU
http://ark.intel.com/Product.aspx?id=47916

Chassis + 1000 W PSU
http://asbis.sk/intel-sc5650ws-pilot-point-t-ws-chassis-1000w-psu_d96431.html

Can you help me with memory?

Any others sugustions or Ideas?

It needs to be DDR3, Registered, Unbuffered...

This is the tested memory list for that motherboard:

http://serverconfigurator.intel.com/configure-memory.aspx?id=MTY2NCMxLDI1MTcjMSwyNjE4IzIsMjUzMyMx&ShowNavigation=false

(the link was inside a PDF found on Intel's page for the motherboard, below a long list of Intel parts and accessories)

You can look up the part number on asbis... ideally you would use three dimm's on each processor, so a total of 6. You'll need at least two, one for each processor.

Be careful what case you pick, get one that accepts the motherboard layout SSI EEB (12” x 13”) which is slightly bigger than ATX.

According to some reviews here :

http://www.newegg.com/Product/Product.aspx?Item=N82E16813121378&nm_mc=OTC-RSS&cm_mmc=OTC-RSS-_-Server%20Motherboards-_-Intel-_-N82E16813121378

you need a power supply that also has 2 8 pin connectors for the processors, along the regular 24 pin connector. And apparently it's "picky" about memory so be double careful about what you get.

[lolmao500]

Now we need x264 encode benchmarks with the 8/12 cores Magnycours new processors...

Or maybe buy 4 NVIDIA GTX480 video cards and encode using CUDA... maybe it would be faster.

[Blue_MiSfit]

My new baby is the 6 core Xeon :) FANTASTIC performance!

~MiSfit

[Adub]

Oh how it sucks being a college student sometimes.

Still kicking along on my old Q6600. You know, I could overclock it now that I think about it. But then again, our power bill has been a bit high recently. Damn.

Blue_MiSfit,
One of these days I'm going to own a darn server farm just to say HA! I WIN!

In all honesty, something with some of the new smoking I7/I9's is going to be sweet, plus DDR3 overclocked like crazy should be fun.

[Biggiesized]

You think that's bad? I'm still chugging along with my E6400 and only occasionally do I overclock it to 3.2 GHz.

[Avisynth_challenged]

You say acceptable encoding time is 3-5 days.
You also say average encode has 180000 frames.

180000 frames in 3-5 days = 0.4-0.7 fps (<- this is your "requirement").

Your first answer said an i7 920 with maxed settings (placebo) on 1080p does 0.8 fps. This not enough?

A couple questions:

I'm assuming that the hypothetical encode cited above is of a 1920x1080@23.976fps progressive source, but...

1. In the estimate above, would this be for a 2-pass VBR H.264 encode? Or is this estimate for a single-pass encode? (And thus, doing 2-pass would double the encode time?)

2. In the estimate above, would the encode scenario be frameserving the original source into the H.264 encoder via an Avisynth script? Or is this assuming an intermediate AVI (i.e. Huffyuv) of the original source is the input of the H.264 encoder?

Just wondering under what conditions does the 0.8fps encode speed apply. Thanks!

[lolmao500]

Anyone knows good GPGPU CUDA x264 encoders?

Instead of buying a dual CPU, you could buy 2 NVIDIA video cards and you would encode much faster for much cheaper.

[Blue_MiSfit]

There is no CUDA acceleration available for x264. There are other H.264 encoders which use CUDA, but nothing so far has been a compelling alternative to x264 (for most usage cases).

~MiSfit