x264 encoding on quadcore ARM CPU. Does it worth it?

[SledgeHammer_999]

Since I read about the Raspberry Pi I've discovered other boards which offer quadcore ARM cpus and are quite cheap.

My question is, how fast is the x264 encoding on these CPUs, compared to an AMD x2 4200+ cpu? Is it worth buying one and have it do encodes day after day?

I suppose the image quality would be the same as the one from being encoded on x86 cpus, right?

(I am looking for a really cheap way to have an "encoding" machine, as my main PC is used for other purposes...)

[paradoxical]

This (http://www.phoronix.com/scan.php?page=article&item=pandaboard_es&num=10) has benchmarks at the bottom running on an OMAP 4460 dual-core A9. It's about a year old so not sure how relevant it still is nor the exact version they tried. Nor does it give any info on the commandline used or information on the inputs used. It's also Phoronix whose accuracy when it comes to benchmarks is questioned often. But it's about the only thing I could dig up in 5 minutes.

[SledgeHammer_999]

As you said not enough info. 1.87fps doesn't tell me anything because I don't what kind of clip it encodes nor the parameters used so I cannot compare it to my current amd 4200+ cpu...

[LoRd_MuldeR]

I think those ARM SoC's are more in the league of an Intel Atom or an AMD C-series processor, so performance-wise you won't get anyway near a halfway decent (x86) Desktop or Laptop CPU - FPS per Watt may be a different topic though. Remember that all those SmartPhones and Tablets only feel "fast" because their software is highly optimized for their weak CPU's and because they make heavy use of GPU-acceleration for all the fancy UI stuff.

Also another thing to consider: What OS are you going to run on the ARM CPU? Probably some ARM-based Linux variant. Does that compile x264 with FFMS2/libav support at all? If not, how are you going to feed x264 with input? Most of the video tools you are used to probably won't be available...

(And don't even think about Windows RT! You cannot get it alone, only pre-installed on Windows Tablets. And it only runs "Metro" apps, no native code!)

[SledgeHammer_999]

I think those ARM SoC's are more in the league of an Intel Atom or an AMD C-series processor, so performance-wise you won't get anyway near a halfway decent (x86) Desktop or Laptop CPU - FPS per Watt may be a different topic though. Remember that all those SmartPhones and Tablets only feel "fast" because their software is highly optimized for their weak CPU's and because they make heavy use of GPU-acceleration for all the fancy UI stuff.

So it would be at least at half the FPS I get with my amd 4200+ (which I consider quite slow).

Also another thing to consider: What OS are you going to run on the ARM CPU? Probably some ARM-based Linux variant. Does that compile x264 with FFMS2/libav support at all? If not, how are you going to feed x264 with input? Most of the video tools you are used to probably won't be available...

As you guessed I would run Linux and probably Debian. It provides packages for ARM. And I suppose I could compile x264+ffms2 myself or feed the raw input from gstreamer... But yeah I would need to devote time on this to get things working. Maybe it doesn't worth it.

If anyone is wondering, I was looking at this board: http://www.hardkernel.com/renewal_2011/products/prdt_info.php?g_code=G135341370451

[me7]

A few weeks ago, I read an oversimplification in an article stating that current ARM CPUs are comparable in raw performance to x86 notebook CPUs from 10 years ago. Even though this isn't exactly precise, it should give a good picture of what to expect for serious encoding.

LoRd_MuldeR already mentioned that smartphone OSes cheat to stay fluid and responsive. They offer limited multitasking and use long GPU-powered transition animations to hide (!) loading times.

[SledgeHammer_999]

As it seems encoding needs raw performance(duh) which isn't in ARM's advantage. (I also rephrased my previous response)

[LoRd_MuldeR]

FWIW here are some CoreMark results:
http://img515.imageshack.us/img515/4499/coremark.png

(Source: http://www.coremark.org/benchmark/)

[mandarinka]

In this case, the earlier Phoronix benchmark should be relatively representative. Cortex-A9 is in fact slow, and x264 lacking some ARM assembly doesn't help (this situation doesn't seem to be going to change anytime soon).
As you can see there, a quad Cortex-A9 is more or less certain to be beaten by dualcore atom (which can be got for peanuts togetehr with motherboard). In that comparison, you can see Pentium M and Core Duo too, but those are old 32bit only chips that have lousy SSE2 performance. If he tested against Celeron G540/G550 (very cheap CPU), not to mention a Core i3 (relatively expensive), the performance difference would get much wider.

In any case, buying that ARM thing as an extra device for encoding doesn't make any sense financially. Your current CPU (K8 architecture) isn't very powerful for x264 encoding, but any money are much better spent on a hardware upgrade for your main PC.

The Athlon II X4 cpus for socket FM1 seem to be really cheapo (and motherboards can be probably got cheaply too, since the platform is at the end of its life), and should give good performance at the expense of relatively higher power consumption. You need to have a dedicated GPU too (if not, A6-3670K and A8-3870K aren't expensive either). If you want something cheaper, get Celeron G550 (it also consumes little power in load, around 40W).

[hajj_3]

here there are some Cortex A15 dual core results: http://www.phoronix.com/scan.php?page=article&item=samsung_exynos5_dual&num=5

the dual core isn't much slower than the atom d525, tegra 4 has quad a15 btw, would be nice to see benchmarks of that. Here are some other benchmarks of dual core cortex a15: http://www.phoronix.com/scan.php?page=article&item=samsung_chrome_a15&num=3

these benchmarks were done in chrome os btw not ubuntu linux.

[mandarinka]

Yeah, but can you get a board with such quad A15 *for cheap*? (Compared to a conventional CPU/board/ram.) And also count in various obnoxious aspects - OS, need to compile your own x264 /perhaps uncovering bugs that nobody else catched before, cuz the platform isn't used/.

BTW, by the time such (developper probably) boards get released, they will probably have competition from Jaguar-based quadcores from AMD (15-25W TDP reportedly). That core will have 128bit SIMD and some new instruction sets (up to AVX). It probably won't makes sense to use exotic ARM board instead of that, even if you care about power usage. (Cortex-A15 actually has rather high load power draw, much higher than Cortex-A9: look here (http://www.anandtech.com/show/6536/arm-vs-x86-the-real-showdown/9))

You can also get ITX motherboards with integrated Celeron 847 (1,1 GHz × 2, Sandy Bridge, 17W TDP) today. Sandy Bridge with disabled HT and AVX encodes at least 2× faster than Atom, clock for clock. But it is better to get a higher-frequency processor instead.

[Dark Shikari]

x264 is used on ARM a decent bit (especially by x264 licensees), so it's not an unused platform, though certainly not as used as x86.

[aegisofrime]

x264 is used on ARM a decent bit (especially by x264 licensees), so it's not an unused platform, though certainly not as used as x86.

Can I ask, what would be the easiest way to get it running on Android? I wanna try it on my Nexus 4 (4 x Krait)...