Sunday, October 5, 2014

Bay Trail NUC (DN2820FYKH) Review - part 2

"Building an home theater PC (HTPC)?" is the first thing Intel says on their website. It's clear that this NUC is designed to be the budget HTPC platform. It's got many good characteristics for a HTPC: it's small, it's quiet, it consumes little energy, it's affordable and there's even an integrated infrared sensor.

I previously wrote an article about the DN2820FYKH NUC and it's characteristics. Today I'm going to take a look how the Bay Trail NUC works as a HTPC.

As the Bay Trail NUC is the cheapest Intel NUC with a price tag of only around $130 I think it's natural to pair this NUC with a free operating system. OpenELEC is an open-source project which is designed for one purpose - to run the XBMC/Kodi media center application as smoothly as possibly. You can literally have a full media center running in 15 minutes with OpenELEC.

Furthermore, it strikes as kind of odd to spend a $100+ for a computer and then about the same for a copy of Windows 8. OpenELEC will run just fine with only 2 gigabytes of memory, whereas Windows will require at least 4 gigs to run ok.

OpenELEC on DN2820FYKH


I installed the stable version 4.0.7 of OpenELEC on the NUC. What can I say? Everything worked out of the box: even the wifi card and the IR sensor. I just had to change my settings so that audio was output to the HDMI connector to get the sound out via the TV speakers.

Navigation was smooth, even using a heavier skin like Aeon MQ5. Pretty much all the comments that applied for OpenELEC on the DE3815TYKHE actually do apply for the DN2820FYKH as well. It's perfect for 720p and 1080p content, but if you need live TV or interlaced content, you'll bump into the limits of the CPU and GPU of this small PC. Read the DE3815TYKHE article here.


OpenELEC on Intel NUC DN2820FYKH by nucblog (enable subtitles to see commentary)

Full HD playback


I tried testing out a few 1920x1080 24p videos and the playback seems to be ok. It's good to make sure that the following settings are configured in XBMC:
  • Video - Playback - Adjust display refresh rate to match video: On start/stop
  • Video - Playback - Sync playback to display: Enabled
  • Video - Playback - A/V sync method: Video clock (Drop/Dupe audio)
  • Video - Acceleration - Decoding method: Hardware accelerated
  • Video - Acceleration - Allow hardware acceleration (VDPAU): Disabled
  • Video - Acceleration - Allow hardware acceleration (VAAPI): Enabled
  • Video - Acceleration - Use Mpeg-2 VAAPI: Enabled
  • Video - Acceleration - Use Mpeg-4 VAAPI: Enabled
There are a few very high bitrate test videos at jell.yfish.us that I tried. I tried the 100 Mbps video and even that was fine. There were no dropped frames during the playback. There are a few right in the beginning of the playback, but it stabilizes after first second or so. Do note that in real life most of us will not face a video with 50 megabits/s...

Does It Do 24p?


After the problems that Intel GPUs have had with displaying the 24p content another question everyone had was if the NUC can do proper 24p, meaning not 24 frames per second but 23.976 frames per second. And yes, it seems that the Bay Trail GPU gets the check mark.

Scaling


If you are watching content that is not in 1920x1080 resolution such as a normal SD television, DVD content or even 720p HD content it needs to be scaled up to 1920x1080 resolution by the HTPC. Now comes the bad news, the GPU in this NUC is too slow to support anything except the Bilinear scaling. Bilinear in my opinion is fine for 720p to 1080p scaling, but for SD TV to full HD it produces quite a blocky picture. Especially diagonal lines look bad with bilinear scaling. Note that this is only a concern with SD content, for HD content no scaling is required.
100% crop from a video where SD content has been upscaled.

Deinterlacing


Deinterlacing comes into play if you are watching interlaced content. That is typically live TV content or content recorded by a live TV backend such as Tvheadend. Due to historical reasons TV is often broadcasted in a format where only every other line is drawn on the screen (ie. for 1920x1080i video there's only 540 lines of information at broadcasted at any given moment). This was fine with CRT screens, but modern LCD screens do not really support interlaced content. Thus it needs to be deinterlaced before it can be shown properly. Deinterlacing can be done in many ways and the more sophisticated ways consume more processing power but also provide a better picture.

The graphics drivers for the Intel HD Graphics on Linux are currently in an unfortunate state and the deinterlacing is not really working as it's supposed to work. Thus the alternative is to use CPU for performing the deinterlacing. This works ok for SD content, but for content broadcast in interlaced HD format (1080i) the feeble CPU in the NUC is not able to handle the deinterlacing. Only the plain BOB works, but that provides a jittery image.

Another, rather annoying issue with the software deinterlacing is that you need to enable the option Video - Acceleration - Use SW Filter for VAAPI and then you can choose even Yadif as deinterlacing method (Yadif equals to Deinterlace method De-interlace in the settings) which provides the best result and this is fine for the SD content. However, when you try to play non-interlaced 1080p content, the SW filter option will consume CPU even if there is no deinterlacing to be done. Thus you need to switch off that option if starting to watch a 1080p video.

Again, deinterlacing is probably only an issue if you are watching live TV with your HTPC. Almost all streamed content is in progressive mode and does not need to be deinterlaced. It seems that some work is being done to enable hardware accelerated deinterlacing on the Intel GPUs, so this situation might improve in future.

Live TV


I've successfully installed Tvheadend and watching SD live TV content is not a problem. Interlaced HD TV probably is an issue due to the interlacing woes mentioned above.

DN2820FYKH as HTPC


The DN2820FYKH has lively performance in the menus and good performance when playing full HD videos. It's significantly faster than a Raspberry Pi for example (but that's an unfair comparison) and OpenELEC works smoothly out of the box on it.

On the other hand the Bay Trail NUCs suffer from having only 4 execution units in their GPU. As a result the upscaling and deinterlacing functionality with the current drivers leaves something to be desired. The same situation applies to all Bay Trail motherboards currently.

There's also another BayTrail NUC, the fanless DE3815TYKHE, but considering that it is sold for more or less the same price as the this NUC (DN2820FYKH), I'd say unless you really desperately want a fanless system, go for the DN2820FYKH. Better yet, go for an i3 model and you don't need to ever worry about upscaling or deinterlacing. Don't get me wrong, this NUC is a fine small PC, but you should be aware of its limitations.

More about DN2820FYKH


Read the other parts of the review:

2 comments:

  1. I guess I look elsewhere to stream live TV over network. Thanks

    ReplyDelete
  2. I would like to know how to obtain HW acceleration in Lubuntu on it. I failed trying this... :( So I caved in installing W8.1 and there it works fine.

    ReplyDelete