[mythtv] Video as time base stopped working on EPIA with recent CVS

Darren djsharman at ntlworld.com
Sun Apr 11 11:49:04 EDT 2004

Henk and Steve,

Yes I run the frontend as root, in fact the distro I use is a diskless
version of gentoo that I modded myself and that doesn't have anything
other than root.

I have solved the problem I was having, after reading the comments Henk
wrote about process priorities being boosted I removed some "nice"
script commands that I had put in myself when trying to get smooth
video. Now the frontend is working again.

As to whether the video as timebase is actually working for me. I think
it must be, I guess I'm not using the nvidea timebase though as the
video is provided from the northbridge chipset which I think is S3
based. Anyway the reason I think its working is that when I start
viewing a channel, I can see the audio is out of sync and hear it warp
into sync (it sounds quite funny on a music channel). The main thing for
me is that the video is smooth.  

I would like to know more about how this mechanism works, so Steve, if
you have some time can you contact me off list to discuss it. Failing
that, can you point me to the significant section of code.

Thanks to both of you for replying,



On Sun, 2004-04-11 at 16:06, Henk Poley wrote:
> Op zondag 11 april 2004 16:38, schreef steve at nexusuk.org:
> > Hash: SHA1
> >
> > On Fri, 9 Apr 2004, Henk Poley wrote:
> > > 1) Sure it really worked before? The dev of this thing told me it only
> > > works with nVidia cards. Possinly you ran it on it's primary fallback
> > > method.
> >
> > Oops, yes I forgot to point this out in my previous mail - the option uses
> > the /dev/nvidia device.  If you don't have that device then it will fall
> > back to /dev/rtc and as a last resort, usleep().  But generally if you
> > don't have /dev/nvidia it's not worth using it instead of the normal
> > experimental AV sync option.
> What about showing this info (needs nvidia, and root) in the 'tooltip' at the 
> bottom of the settings screen? Might reduce the number of people who report 
> errors when using it.
> > > 2) You still run the frontend as root? As since the thing can only acces
> > > the vsync info as root, and can only relyably fall-back to precise
> > > timeing information by the kernel as root. As a normal user it will fall
> > > back to using usleep(), which would be (and is) crap.
> >
> > AFAIK running the frontend as root is recommended anyway isn't it?  Since
> > the frontend likes to increase it's process priority on some threads
> > (which only root can do).
> I think I heard that somewhere before, but I never seen these 'higher' threads 
> nor seen any better behaviour. And doesn't Jarods guide use GDM? That login 
> manager doesn't do root auto-login (at least my mine doesn't). So I think an 
> awfull lot of people run their frontend as a normal user. (Unless Jarod bases 
> it on an SElinux kernel...)
> 	Henk Poley <><
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