[mythtv-users] Bob's Huge List of Questions [Was: 0.22 annoyances]

[Bob Cunningham]

On 01/05/2010 07:25 AM, Johnny wrote:
>> His opinion surprised me.  In short, he said: "Put all your work into a
>> feature-rich UPnP backend, then get a SageTV or Popcorn or similar media box
>> for each TV."  From the perspectives of cost and ease-of-setup, this advice
>> seems logical.  If I can get a box that's just smart enough to let me to
>> access MythWeb, then it would seem I don't really need a MythTV frontend,
>> and thus wouldn't need an HTPC.
>>
>> Comments?  Reactions?
>>
>> What would the best Media Player box be, assuming it would be talking to a
>> MythTV backend?
>>
>> If this strategy seems prudent, then next step would be to craft the best
>> bang-for-the-buck MythTV backend, which I assume would be a vastly simpler
>> problem to solve (a 3 watt PlugComputer + HDHR?).  In which case, I'll not
>> hijack this thread, and will start another thread for that subject.
>>      
> I don't agree. Going with UPnP device will limit your ability to use
> some of the best features of MythTV. You would generally need more
> than a 3 W plug computer for the backend, although not too much more.
> You need disks, a CPU that can handle the database, commercial
> flagging, etc, and you want to have a good network (I would go with 1
> Gbps if I was starting out). The idea with a backend only machine is
> that it doesn't need to be pretty or quiet. You can put all the disks
> you need in it, etc, and then just stick it somewhere where you don't
> see it or hear it.
>
> In the past it would have made more sense to go with something like
> that popcorn hour, but now you can get a variety of small, quiet ION
> based frontend machines for approximately $200. So they will have
> basically the same footprint as a popcorn hour, but you get a full HD
> capable frontend. So you get a full frontend that can do commercial
> skip, time stretch, scheduling, etc. Also you can run other things
> like XBMC or Boxee on there if you like. I don't see a compelling
> reason to go with a UPnP frontend at this point.
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>    
Last night I searched for ION boxes, and was pleasantly surprised: 9400M 
graphics +1.2 GHz CPU for US$200!  Power consumption still seems massive 
compared to the SageTV-type boxes, but it's a lot less than a regular 
PC.  And, yes, the cases are tiny.

I suppose my initial joy at the thought of using something like a SageTV 
box was simply due to the fact that I'd not have to do any significant 
hacking to get instant functionality.  But with a MythTV frontend, once 
the first one works, cloning will be easy.

After taking a quick look at the entire *minimal* processing chain from 
the cable TV to the disk and to the TV, the only part that always 
requires significant CPU horsepower seems to be SD compression (the vast 
majority of my channels are still SD).  A quick check shows it uses 
about 25% of a 3 GHz Xeon core, meaning it could saturate a 1 GHz 
single-core CPU, especially with multiple SD tuners.

Are analog tuners with hardware compression worth it?  Do any 
USB/Ethernet analog tuners support SD compression?  (I haven't found any 
via Google.)   Can I somehow use the GPU for SD encoding?

The next most CPU-intensive operations seem to be transcoding and 
commercial-flagging.  Since this does not need to be done in real-time 
on the backend, this means I'd simply have to use the TV tuner for 
LiveTV.  An acceptable trade-off, since I seldom watch LiveTV.

Let's say I get an analog tuner with hardware SD compression (I *really* 
wish the HDHR had two of them).  Can I do transcoding and flagging 
without an FPU?  Can I consider using an ultra-low-power ARM CPU on the 
backend?

TIA,

-BobC