[mythtv-users] 2 analog capture cards pushing AMD64/3200 to >=100%?

Chad masterclc at gmail.com
Fri Jun 24 20:53:58 UTC 2005

On 6/24/05, Poul Petersen <petersp at mail.alleft.com> wrote:
> > Now, in these last couple of days I've solely been struggling to get
> > audio working.  Finally, it looks like that's a go.  However, during
> > this testing, I see the system crawling.  The backend is sucking up
> > ~55% of CPU time (according to top) for a single recording for a
> > single card.  But I've got 2 cards, and I expect this machine to also
> > be a FE for HDTV.  Yes, the cards are cheapo analog cards using bttv
> > drivers (WinTV Go cards).  But I thought if I spent the money on a
> > decent CPU, I wouldn't have to worry about the amount of cycles
> > absorbed by the lesser card.
>         Hmm. That does seem a little high for a frame grabber, but
> then it all depends on what settings you are using. I've got a
> XP 2200+ with two WinTV Radio cards (and an Air2PC card incidentally).
> I have the bttv cards set to capture 480x480 Mpeg4 and when they
> capture they use about 38% of the cpu each.
>         Personally, I'd ditch the bttv cards and get some flavor
> of PVR. I had weird crashes that seemed to be the result of
> starting simultaneous bttv recordings on a single backend.
> When I "stripped" my bttv cards across backends, the problem
> lessened, but every now and then I would be recording three
> shows at once (so at least two on one of the backends) and it
> would blow up (not everytime mind you - and if I rebooted the
> machines regularly it would further lessen the problem) But since
> I added a PVR250, my machine has been up for months. I'll
> probably buy a PVR500 or two shortly and throw away my WinTV
> cards...
> -poul

Thanks for the suggestion.  I do remember reading threads about the
different resolutions, what was optimal for a situation, but don't
really remember CPU coming into play.  But I should have figured on

I'll lower my bitrate a bit (mpeg4 also), I think I've got it cranked
pretty high, something like 6000 I think.  I wanted it high so I could
transcode lower afterwards; sort of a "give me the best recording
possibly, and then transcode that" strategy.  However, maybe I'll just
start on a lower bitrate to begin with, and then take out the
transcoding step since the originals will be around the same size..

I'd really like to get a few of the PVR flavors here, but I had a very
hard time justifying what I have, to add to it at this point would
really be a bad idea.  I am certainly looking for that as a solution
in my future, but I would like to get this deployed as is for now, and
then upgrade to PVR's later as the need arises for more cards.


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