[mythtv-users] Which NVidia card

Michael T. Dean mtdean at thirdcontact.com
Mon Jan 21 17:50:00 UTC 2008

On 01/21/2008 09:34 AM, Steve Smith wrote:

>  On 21/01/2008, Cal <cal at graggrag.com> wrote:
> > Marius Schrecker wrote:
> >
> >> After a Loooong break I'm trying to breathe new life into my
> >> MythTV box.
> >>
> >> Why didn't I listen to you all before when you warned bout ATI
> >> cards? I'd have saved myself a lot of grief! Anyway:
> >>
> >> Now I'm going to get a card that does proper XvMc (Nvidia the
> >> only choice here??)
> >
> > Forget about XvMC. It's a relic of a past era where our poor
> > struggling sub-2G single core cpus _needed_ some graphics
> > processing to be offloaded in order to survive. So, the poor little
> >  graphics card endured constantly cooking up a storm doing XvMC,
> > and without even a fan to cool its brow. Now, I believe you're
> > better off letting a nice little dual core do the hard work. It's
> > better equipped to deal with the heat output too.
> >
> > Worst of all, XvMC comes with some tedious artifacts. You don't get
> >  anything for free. My suggestion is have the graphics card do no
> > more than it has to, and provide the necessary grunt via cpu
> > instead. I have a 6200 and a 7300 (two systems), and I really can't
> >  pick between them. They're both excellent as long as I don't try
> > to include XvMC in the mix.
>  That's an interesting take on the use of XvMC.

I completely agree with Cal.

>  My opinion is use a specialized tool for a specialized job.

But the problem is that the specialized tool was designed only for video 
decoding.  It was not designed to be specialized for MythTV.  Software 
decoding gives you full benefits of Myth--you can display /anything/ on 
the output--on top of the video, around the video, ...  whatever people 
might think of in the future.

Another way of looking at is by taking a look at the simpler example of 
audio decoding.  If you do "hardware decoding" of AC-3/DTS (i.e. 
passthrough to an external amp/receiver/processor), you lose out on 
things like timestretch, adjusting the audio to compensate for A/V sync 
issues in the video, ...  If, instead, you decode the AC-3/DTS in 
software, Myth has full control over the audio output--enabling it to 
speed it up, perform pitch control, ... eventually perhaps volume 
normalization or whatever.  Of course, in the case of audio, the 
passthrough currently has the benefit of multi-channel surround output 
and the ability to use the much higher quality D/A circuits in the 
amp/receiver/processor as compared to the D/A in your sound card (though 
software decoding will gain this benefit after #1104).


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