[mythtv-users] Myth TV on server

Robert Johnston anaerin at gmail.com
Sat Nov 6 04:11:59 UTC 2010


On 05/11/2010 7:34 PM, Gavin Hurlbut wrote:
> On Fri, Nov 5, 2010 at 5:24 PM, Robert Johnston<anaerin at gmail.com>  wrote:
>>> Additional computer specs:
>>> MOBO: Tyan Thunder K8SR
>>> CPUS: 2 AMD Opteron 270 Dual core 2.0Ghz.
>>> memory: 4 gig
>>> Hard Drive: 1TB drive, 3 empty SATA ports.
>>
>> Okay, first of all, that is MASSIVE overkill for a backend server! It
>> doesn't need anywhere near that amount of processing power.
>
> I totally disagree with that evaluation.  If you end up doing HD
> captures, especially with HD-PVR (over USB), you will want a nice
> powerful server as the commercial detection will require plenty.
> Other than being PCI-X instead of PCI-E, this server is fairly
> comparable-ish to the i7-860 (quad core) box I built for my backend
> recently.  And you will almost assuredly run out of disk space :)

Disk space is a given. :)

As for processing power, wasn't there a patch submitted recently that 
used 1/4 the size for HD commercial detection (De-ressing the video to a 
quarter of it's size). Given that commflagging doesn't need to be 
HD-accurate, this is a good step, and would reduce the needs for 
commflagging to less than that quad core monster. Unless, of course, he 
was commflagging 4 channels at one. :)

>> IIRC, PCI-X is backwards-compatible with PCI, so you could use a PVR
>> 150/250/500 to capture from your cable box just fine.
>
> PCI-X is 66MHz 64bit PCI, IIRC.  So yes, you should be able to use
> PVR-x50.  However if you intend to do HD captures, you are down to
> using either the HD Homerun (connects via ethernet) or the HD-PVR
> (USB).  Almost all current capture cards are PCI-E.
>
>> This will give you Standard Definition recording. If you want High-Def (And
>> if your cable box supports it) you could get a PCI Firewire card and hook it
>> up to the cable box. Then, in thoery, you would get a HD capable feed, and
>> the channel change commands could (if it's a supported unit) be sent over
>> firewire as well, making it a self-contained solution.
>
> There are a *lot* of "ifs" in that scenario.

Yes, there are. But there's no real way around it. If cable standards 
were more open (CAM/CableCARD on QAM for any platform being 
allowed/enabled) it wouldn't be an issue, but as the Cable TV industry 
is (quite deliberately) obfuscating and encrypting everything they can 
to prevent their customers from using the services they have paid for in 
a manner they are legally entitled to, recording HD cable TV on Myth (Or 
on anything else, for that matter) is going to be a massive decision 
tree of Ifs, buts and maybes.

"Best case" scenario:
Cable company provides TV in unencumbered form (Clear QAM, IPTV).

Second best scenario:
Cable company enables Firewire port on boxes.

Worst case scenario:
Cable stream and box are encrypted, firewire is disabled, Component is 
down-scaled (480p), HDCP is enabled.

In the worst case scenario, I'd suggest dropping the TV portion of your 
"Cable TV" altogether, and using Hulu or setting up a torrent box.


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