mythtv and digital tv

[Frank DiPrete]

Ben Scott wrote:
> On Thu, Jul 24, 2008 at 6:36 PM, Frank DiPrete <fdiprete at comcast.net> wrote:
>> I like the HDHomeRun card ...
> 
>   Just to make sure it's clear, the HDHomeRun isn't a card, it's an
> external box (about the size of a cigar box).  It uses a wall-wart
> type power supply transformer.
> 
>> If the card had hardware encoding it would be perfect.
> 
>   Encoding or decoding?

Encoding on the backend where the card goes.

http://www.pchdtv.com/hd_5500.html

The HD-5500 Hi Definition Television PCI Card is an universal PCI 2.2 
compliant card. The card receives NTSC, ATSC and Cable/QAM Signals and 
converts them to digital streams which are transported across the PCI 
bus. Display and MPEG2 decoding are done on the host computer

> 
>   For digital broadcast -- be it cable or ATSC OTA -- the stream is
> already encoded and compressed as part of the transmission process.
> There's no need for an encoder.
> 

The description isn't clear about writing the streams to disk.

The goal is to write mpeg2 files to the server for playback like the 
pvr-250 does via its encoder. I'd like to believe that the term "digital 
streams" means mpg2/aac but the term "digital streams" isn't defined on 
the site. I'll check some mythtv sites about this card to see what is 
involved.


>   The HDHomeRun is digital only; it doesn't even have an NTSC tuner.
> So, to the best of understanding, the HDHomeRun has no use for a
> hardware encoder.  The HD-5500 does have an NTSC tuner; I don't know
> if it has a hardware encoder or not.  Presumably, if you're buying an
> HD-5500, the plan is to switch to digital TV, so NTSC shouldn't
> matter.
> 

Also true. I would not be using an ntsc tuner.

>   For decoding, I believe you'd still be able to use the "small quiet
> diskless box frontend".  The one thing I'm not sure about is: I expect
> not all hardware decoders are created equal.  It may be the decoder in
> your front-end box can't handle this new-fangeled high-def stuff.
> 

The only prediction I have here is "probably OK". playback of the 
recordings I make today (ntsc analog to mpg2/aac at 48K sampling - file 
is a bout 2G per hour) takes 25% of the via cpu while using the mpeg 
decoder chip.


> -- Ben
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