Specs for a Linux HTPC

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theacoustician

[H]ard|Gawd
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Feb 8, 2002
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I thought I'd have a go at setting up a MythTV client/server system. So far, I've been finding most of the information that I need, but one thing seems to be rather lacking and that is hardware specs for 1080p AVC playback. I know that hardware accelleration is non-existant at this point for Linux. Any documentation I can find on playback seems to be rather Windows centric and seems in most cases to assume GPU assist. So does anyone here know exactly what kind of hardware specs you need to decode a 1080p AVC video with no dropped frames or skipping under Linux? I'm assuming at least a Core 2 Duo, right? Video card preference?

Also, if anyone has any experience with setting up roaming profiles or distributed H.264 encoding with something like x264farm, please drop me a line. Thanks.
 
I don't know about 1080p, as I can't seem to find any content to test with, but my mythbox does very well with 1080i / 720p:

x2 3800+ (mildly oc'ed)
7900GS
1Gb of ram

The same system had the exact same performance level (besides goom, which had to be scaled in half, which isn't too bad) with a 7300GT. The system had an opteron 144 (oc'ed to ~2.9Ghz) with the 7300GT, and it did very well with HD video, although every once in a LONG while I'd get a dropped frame or two.

A dual core processor is not *absolutely* required, but I would fully expect it to be put in, since they are so cheap and available now. As for the video card, the ONLY choice you have is nvidia cards using the binary driver from nvidia. It sucks ass that you have to taint your kernel, but that's just how it is right now. Intel has full open-source drivers, but their hardware blows goats compared to the video processing power that nvidia cards have. Ati's drivers are so bad that they don't even qualify as a joke.

I had never heard of x264farm, but after a short bit of googling, it seems to be a distributed encoding system for making h.264 video from other input formats. There is a similar project with MythTV to allow an openmosix cluster to do your commercial flagging and transcoding on a cluster instead of just your backend system. I haven't gotten around to trying it out, since all the older systems on my network have now been turned off in an effort to not waste as much electricity. Mythtranscode is very flexible and you can tweak it to encode just about any which way you like. I have not ever tried any of this before, though.

Out of curiousity, where are you sourcing your 1080p program material from? Captured off of BluRay? You have a buddy who works for the BBC or some other production company? 1080i and 720p is the highest quality content I've been able to get into my mythbox...

By the way, welcome to the mythtv community. Feel free to PM me with any questions you may have. I'm no expert at all, but I'll be glad to help where I can.

-q
 
Thanks for all the good info!

Here's a 1080p AVC clip, if you're ever in need of test material : http://trailers.nerodigital.com/Disney/TheGreatestGame_HD_AVC.mp4 (warning : 100+ megs!). If you get the time, let me know how it looks on your system and what the usage stats look like. As to where I'm getting my content, I'm hoping to get HD-DVD ripping working properly, but also ... let's just say I have a lot of access to original masters where I work :D. Mostly though, I just am using 1080p AVC decoding as the high water mark for what the system will have to do. I want to try and make the client boxes as tiny and quiet as possible but still having the capability of handling anything I can reasonably think will be thrown at them. I know what that translates into hardware wise in Windows, but wasn't sure how much moving to Linux changed things.

I'll definately have to read up more on Mythtranscode. My idea there was to take all jobs in a set encode/transcode queue and script them to run at night when power is cheaper and the heat impact of running a bunch of PCs isn't as great. The server could WOL all clients in standby, farm out the encoding or postprocessing, and then turn everything back to standby when its done. Material might be TV captures, converting DVDs to AVC for smaller storage, or transcoding material to a portable player so its loaded and ready to go when I get up in the morning. I know that's a little ambitious, but I'm bored and need something to do. Currently in Windows, I use AVISynth before encoding to deinterlace, color correct the source, and maybe sharpen it up if needs be. Anything like AVISynth in Linux? I can't seem to find it yet if there is.


What distro are you running Myth on?
 
Thanks for the link to the test material. I'm gonna take a peek at how my system handles it when I get home and I'll report back on how it goes.

I'm currently running two gentoo boxes for my mythtv installation: one hooked up to two firewire cable boxes, the other hooked up to my tv. I like gentoo a lot, but I am seriously considering moving away from it for linuxMCE. LinuxMCE is a wrapper around mythtv, pluto home and a few other software stacks and is built on top of ubuntu. We will see how that goes...

For some light reading: http://gentoo-wiki.com/HOWTO_Install_Mythtv_With_Diskless_Workstations_in_an_OpenMosix_Cluster

-q
 
You can get 1080i acceleration through XvMC if you have an nvidia card I have an Athlon 64 3200+ (2GHz...I think?) on an nforce 6150 board with component out. It handles 1080i content just fine, and I won't be home until the second week of June to try it with this 1080p video.
 
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