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Aurisor
Guru
Joined: 20 Sep 2003
Posts: 361
Location: Boston MA
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 Posted: Sun Nov 12, 2006 10:30 pm Post subject: hardware for mythtv |
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Hello all,
I've suddenly become interested in mythtv. I've done some research, and installing the software seems to be pretty simple. I have a few questions on the hardware endof things, however.
1) I have a P3-733 with 160 gb of hard drive space. Is that enough, or do I need something faster?
2) I have no clue what kind of hardware I need, or what brands are well-supported. I assume I need some kind of tv capture card and a video card with tv out?
Thanks! |
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hans0r
Tux's lil' helper
Joined: 02 Jan 2005
Posts: 122
Location: Germany
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| Posted: Sun Nov 12, 2006 10:33 pm Post subject: |
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http://www.mythtv.org/docs/mythtv-HOWTO-3.html
| Quote: | A PIII/733MHz system can encode one video stream using the MPEG-4 codec using 480x480 capture resolution. This does not allow
for live TV watching, but does allow for encoding video and then watching it later. |
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stdPikachu
Apprentice
Joined: 10 Mar 2004
Posts: 254
Location: UK
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| Posted: Sun Nov 12, 2006 10:47 pm Post subject: |
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| If you're going to be using hardware capture cards (e.g. DVB) then CPU is only a worry if you plan to do lots of transcoding or playing HD content. A P3 is easily capable of playing back SD MPEG4 and DVD content, especially if twinned with a decent accelerated GFX card (e.g. XvMC). |
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Hobbes-X
l33t
Joined: 04 Feb 2004
Posts: 823
Location: Seattle, WA
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| Posted: Mon Nov 13, 2006 4:14 pm Post subject: |
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Yep- it all depends on the hardware on a lower-end system. For a capture card, any of the Hauppage MPEG-2 hardware PVR cards (150/250/350/500) are well supported, although the 350's hardware decoding is less supported now that there's not any myth developers using one. If you've got a Motorolla DCT6200 cable box (or an SA3250) with a firewire output you can also capture from that, although you won't be able to pull encrypted channels. There's also other hardware capture cards out there, including DVB cards mentioned above. All of this is listed in the myth docs along with cards that are known not to work.
For output to a tv you'd probably want a card capable of xvmc, as already mentioned, although even then your system is probably too slow for displaying HD (http://mythtv.org/wiki/index.php/XvMC). If you don't have a card that supports it already, nvidia 5200's with tv-out can be had for pretty cheap: http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=321951
Also, with a slower system there's a few settings you'll proabably want to change. Specifically, there's a setting in mythtv-setup called something like 'Enable Slow Deletes', since deleting multi-gigabyte files can take 10-20 seconds this slowly shrinks the file over time instead, which helps keep things responsive. Also, if you've got other systems up and running all the time, consider keeping the mysql database there instead. |
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stdPikachu
Apprentice
Joined: 10 Mar 2004
Posts: 254
Location: UK
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| Posted: Wed Nov 15, 2006 10:17 pm Post subject: |
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| Hobbes-X wrote: | | there's a setting in mythtv-setup called something like 'Enable Slow Deletes', since deleting multi-gigabyte files can take 10-20 seconds |
Isn't that what JFS is for...? I recommend a JFS filesystem for your tvstore directory, since it is (I believe) the single fastest filesystem at deleting multi-GB files. Never had it take more than a second to delete a file. IIRC Reiser is notoriously slow to delete large files.
Anyway, back OT. You don't say which country you're in, so I presume the US where analogue cards still seem to be the norm. If however you're in Europe and you get DVB broadcasts in your area, don't hesitate to grab a DVB card. Much easier to set up IMHO, and the quality knocks my old PVR-250 into a cocked hat. Their hardware requirements are about the same as hardware analogue cards (i.e. practically nothing as long as you don't have a VIA chipset, which are notoriously flaky with the large amounts of DMA traffic that TV cards create). As for brands, I've never had a problem with my Hauppauge cards (Nova-T's and the aforementioed PVR-250), not my Avermedia 771.
You can use a TV-out, but I found I got much better image quality (before I upgraded to my swanky new TV with DVI input) with a video convertor that took a VGA input and spat it out to S-Video or SCART. No mucking about with overscan or anything either. |
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Hobbes-X
l33t
Joined: 04 Feb 2004
Posts: 823
Location: Seattle, WA
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| Posted: Wed Nov 15, 2006 11:53 pm Post subject: |
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| stdPikachu wrote: | | Hobbes-X wrote: | | there's a setting in mythtv-setup called something like 'Enable Slow Deletes', since deleting multi-gigabyte files can take 10-20 seconds |
Isn't that what JFS is for...? I recommend a JFS filesystem for your tvstore directory, since it is (I believe) the single fastest filesystem at deleting multi-GB files. Never had it take more than a second to delete a file. IIRC Reiser is notoriously slow to delete large files.
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I personally use ext3, because it's simple to shrink and grow partition sizes. I've got an LVM array for my system and having the flexibility to shrink a filesystem has come in handy when shuffling disks in. I'm not using the slow deletes option, and I haven't noticed any problems performance-wise, but it's not taxed all that much.
There was a post on the mythtv-users list where someone posted their delete times:
| Quote: | My last reply to myself. Based on a Googled reference, I was able to
break my XFS 4G file size barrier by formatting the partition 'mkfs.xfs
-dagsize=4g'. So, here are the complete results:
Time to delete a 10G file, fastest to slowest:
JFS: 0.9s, 0.9s
XFS: 1.3s
EXT3: 1.4s, 2.3s
EXT2: 1.6s
REISERFS: 6.2s
EXT3 -T largefile4: 5.9s, 10.2s
After running the XFS test, there didn't seem to be any point in
reformatting the partition again, so I left it on XFS, but I think I
would be happy with JFS, XFS, or EXT3 w/o '-T largefile4'. |
Not particularly detailed, but it's enough to get an idea- JFS is the fastest, Ext3 with largefile set and Reiser look rough... If you've got reasons for sticking with something else I can't see that it would do much damage with the faster filesystems there. Of course, I don't have a clue what disk I/O looks like with those numbers, but it might be nice to have the slow deletes option to smooth things out on a P733 and leave some breathing room for the system.
| Quote: |
You can use a TV-out, but I found I got much better image quality (before I upgraded to my swanky new TV with DVI input) with a video convertor that took a VGA input and spat it out to S-Video or SCART. No mucking about with overscan or anything either. |
Very true- even worse is getting the tv-out working in the first place.  I started out with s-video out on a nVidia TNT2, and have since moved to using a projector that takes a VGA input and it made a big difference in quality and ease-of-setup. |
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lonegd
Apprentice
Joined: 07 Dec 2003
Posts: 185
Location: UK
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| Posted: Wed Nov 29, 2006 11:39 am Post subject: |
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| stdPikachu wrote: | I recommend a JFS filesystem for your tvstore directory, since it is (I believe) the single fastest filesystem at deleting multi-GB files. Never had it take more than a second to delete a file. IIRC Reiser is notoriously slow to delete large files.
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GNU/Linux gives us a great choice of filesystems  Both JFS and XFS are great filesystems, but I *personally* prefer XFS. Many (many) years ago I used to use SGI's alot and so have a long history using it. It's well suited to multimedia apps and managing very large files. File deletion isn't the main priority from a PVR filesystem IMHO, multi file read and writes are the main use - imagine reading ( watching ) one stream, while writing ( recording ) two others.
Theres a few interesting benchmark's around, but TBH any of the standard ( ext3, JFS, XFS ) filesystems should be fine for your bog standard PVR.
_________________
Mark Cooper
http://pvrhw.goldfish.org/ - Open Source PVR Hardware Database |
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Hobbes-X
l33t
Joined: 04 Feb 2004
Posts: 823
Location: Seattle, WA
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| Posted: Wed Nov 29, 2006 6:09 pm Post subject: |
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| lonegd wrote: | | File deletion isn't the main priority from a PVR filesystem IMHO, multi file read and writes are the main use - imagine reading ( watching ) one stream, while writing ( recording ) two others. |
Yeah- the only reason file deletion performance is an issue is that it can cause myth's interface to stop responding while you wait for it to delete the file. The slow deletes option takes care of that though, so it's not really an issue anymore. |
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