[mythtv-users] PVR 250 vs 350 vs no hardware encoding; Dolby audio

[Robert Denier]

I picked up an x-pert tv-pvr by v-stream on newegg

TV TUNER KWRLD CAPTR VS-TV878RF (Qty=1,Price=$36.50)

It seems to allow mpeg4 encoding and playing back on athlon 2500 systems 
although I think if you turn the settings way up, you get a little slow 
down.  I probably need to switch away from reiserfs as per the 
recomendations eventually. (kernel 2.6.10)

These cards seem to have a bit of area digitalized that doesn't have 
picture when connected to my dish network receiver.  This is nothing 
new.  I got the same results when I used ati all in wonder cards in 
windows so I don't think its a fault of the card.

One possible advantage of recording directly in mpeg4 is if you can 
avoid transcoding it later when you make the final copy.  I don't know 
if thats possible.  Of course the mpeg4 versions will take up less disk 
space, but the mpeg2 versions will likely be a little sharper in the 
short term.  (Mpeg2 was last I looked a little sharper than mpeg4 when 
data rates aren't an issue, but that may have changed.  It was a close 
thing anyway.)

Afaik with the Hauppage cards that do mpeg encoding in hardware and feed 
the stream as needed, so you don't use any cpu time.

What I would really like that will _NEVER_ happen is a dish network  
receiver that works directly with myth and allows the decrypted mpeg2 
signal from the satellite to be used directly.  That way there is no 
further loss until transcoding occurs. 

What I would eventually like to see is a lossless codec available for 
the recording process like huffuv.  (There may be something better, but 
the main thing is for it to be lossless.)  That way you could set the 
device to record using that and then transcode to the final form using 
as agressive of encoding options as you wanted.  (Afaik huffuv is 
basically motion jpeg with the error encoded with huffman encoding.)  
With that kind of approach you could, theoretically get better results 
than encoding to mpeg2 first with a hardware card, but those results 
come at the cost of a lot of disk space, at least for a little while.   
Note, that this kind of codec would likely be too bandwidth intensive to 
work across a network unless you had gigabit networking.

I'm not sure about the rest.  You really need someones opinion that has 
compared these side by side.  The quality of the electronics involved 
can sometimes have  a non trivial impact

-Robert





Dan Christensen wrote:

>I'm about to order the components for a system that will run MythTV
>(as well as do other things), and I have a few questions.
>
>I'm trying to decide between the PVR-250 and the 350, or maybe even
>something without hardware encoding.  I was thinking that I would
>store video in a format that allows for higher compression,
>e.g. MPEG-4.  So is there any point in using a card which does
>encoding in hardware?  In fact, would using one of the Hauppauge cards
>mean that video would need to be decoded and then re-encoded, and
>would this cause a loss in quality?
>
>For playback, I believe the 350 can only decode MPEG-2 in hardware.
>Can it display video that is decoded in software?  Or would such video
>need to be played through a separate video card?
>
>I'm not very familiar with Dolby audio.  Is support for this something
>that people find useful when using MythTV?
>
>Thanks for any tips,
>
>Dan
>
>  
>
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