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I have an oldish netbook with an Atom N450 (1.6GHz, 512KB cache) - I've been using it to experiment with MythTV, but it seems really slow, even just to work through the menus! Seconds, sometimes 10 or 20s, to load a new menu. Admittedly from a remote backend, but my older Core1 based laptop seems to be fine with the same setup.

At the moment, "all" I want to do is record/playback SD DVB-T (ie terrestrial not satellite) TV (using a couple of USB tuners). (In future, HD would be good, but I'm sure it'll be time for a new back end & PCIe tuners at that point)

I was hoping to use one of the so-called "nettop" devices which currently seem to be D525-based (1.8GHz, 1MB cache) - is double the cache really going to make that much difference? Or has the internal architecture of the Atom moved on leaps and bounds in between?

Given that I design non-Intel embedded computers for a living I was hoping to get lots of hardcore architecture detail from the Intel website, so I could see for myself, but I can't find it!

So: will a D525 be fast enough to not be the limiting factor on a MythTV backend/frontend combined box? Assume I put enough RAM and a decent hard disk int here... Will it need help with video decode?

Alternatively, are there better low-power options now than Atom for this sort of work?

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closed as too localized by Journeyman Geek, Diogo, Ƭᴇcʜιᴇ007, Randolph West, 8088 Aug 20 '12 at 3:22

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I don't think it's as simple as "will a D525 be fast enough to run a MythTV backend/frontend combined box". There are other factors like the amount of RAM, hard drive performance, and the extent of hardware acceleration from the graphics chipset. I believe a reasonable Atom/ION2 nettop would probably be OK in all these areas, but the Atom platform is rapidly being left behind - there are better options from both AMD and Intel. For instance, AMD E450 based devices are similarly priced but generally faster (on Windows at least) –  James Apr 4 '12 at 15:51
    
@James: Thanks - I'll edit the question to be a bit wider - would you care to turn your comment into an answer? –  Martin Thompson Apr 4 '12 at 16:11
    
You need to be more specific as to want you expect to do besides install MythTV. Playing audio files requires less HW capabilities than SD or HD video. FWIW about 2 years ago I did install Mythbuntu on an Intel D945GCLF2 with a USB ATSC tuner, and OTA viewing did work, although sluggishly. –  sawdust Apr 4 '12 at 20:12

3 Answers 3

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Is an Atom 525 fast enough to run a MythTV FE & BE? Answer: YES. I'm running an Atom 525 Ion2 board with an SSD for s/w, Raid 1 discs for data storage and a PCTV nanoStick 290e and it is plenty fast enough to record two HD channels simultaneously and play back HD TV (not tried recording and playing back at the same time). My understanding is that recording DVB-T/T2 is almost just a question of dumping bits to the disc. Playback requires a fast CPU or a fast graphics chip; the Ion2 has a fast integrated graphics chip so hugely off loads the CPU. There's a lot of discussion concerning whether to use GPUs but for me the answer is simple. The Ion2 runs only with a case fan (might not be needed) and drawers only 25W rather than a fast CPU only machine which might drawer ~100W.

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The overall speed is going to be dependent on multiple factors including the CPU, the amount of RAM, hard drive performance, and the extent of hardware acceleration from the graphics chipset.

The D525 is supposed to be quite a bit faster in terms of pure processing power than the N450 but both are very slow compared to normal desktop CPU's. Not sure what you mean about lack of information on Intel's web site. Between them the following datasheets tell you pretty much everything you could possibly want to know:

The obvious competition to an Atom based system is an AMD Fusion based system. If you were using Windows, I would say that you would be better off with the latter as they are generally more powerful for the same money. However, you are presumably using Linux so there are some complications.

It is important to ensure that your system will be able to use hardware acceleration. The MythTV website suggests that Atom based systems with ION2 graphics are a good choice for the front-end: http://www.mythtv.org/wiki/Choosing_Frontend_Hardware. The site also states that AMD Fusion systems are not yet properly supported. Future versions of MythTV will apparently have better support for AMD based systems.

As for the back end, I'm not very knowledgeable about TV capture but as I understand it an Atom processor is going to really struggle with encoding in realtime on its own. The amount of work the processor has to do is highly dependent on the hardware used to capture the video and I don't know what you will be using. But on a nettop you will be limited to USB devices which may not be as flexible as add in cards. Since you have an existing Atom system to test with you should be able to find out if it will be a problem.

In conclusion, I believe a reasonable Atom nettop would probably be a reasonable choice for the front end providing it has ION2 graphics. However, it could struggle with TV capture depending on what device you use. A small form factor Core i3 based systems with PCI Express slots for upgradeability would be much faster (in general) and more future proof, although obviously more expensive.

There has actually been a similar question already: Will new Acer Revo (with Atom 330) be fast enough to be MythTV client/server?

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It's actually likely to be the contrary to the last answer, if anything. I have a D510 chipset that I run myth on, backend AND frontend and a few other serverish tasks including zoneminder (which does hog CPU sometimes). I use myth with USB nova-t capture cards (3 of them). Capture is never a problem, takes almost no CPU at all. And very reliable. I believe that with the nova-t usb sticks, myth has almost nothing to do other than dump the raw data, or thats how it appears anyway.

However playback is somewhat limited. It works perfectly if you're happy with SD resolution and no filtering or optimisation of the image (the very basic video output option, I forget whether it's CPU-- or another).

The frontend does occasionally crash, although not significantly more than the EPIA chipset I had before (back before the myth team unapologetically broke the epia optimisations)

The menus may be described as slow but not 10 seconds, more like 2-3. Faster and less painful than our humax freesat PVR in fact. (grumble....)

Also streaming to another pc or laptop or tablet using mythweb interface works fantastically, no issues there. I tend to do this more often than watch on the frontend.

The D525 set is supposed to be better, and I believe you should be able to get VDPAU running due to the ion chipset. This could improve matters significantly. I plan to upgrade to this chipset shortly. I had not seen evidence of a significantly improved CPU performance, my reason for upgrading is to shrink the box down and use less power. And VDPAU if I can!

So the short answer is yes, but dont expect too much.

p.s. I run on 1GB ram, which has never been a limiting factor. Ubuntu latest, stock mythtv, 5400 HDD I think, nothing special.

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