[linux-dvb] Re: Channel change delay with DVB-T

[Michal Dobrzynski <michal_dobrzynski@mac.com>]

Is there any sort of script or test program that could be used to 
measure the the delays at the driver level? at least so that I can 
benchmark the performance with different drivers and different 
configurations.

Is it any slower for the driver to lock onto another frequency if it is 
already locked onto one? Given that I have 2 cards perhaps I could take 
advantage of it for channel switching. There are only 5 channels so 
you'd expect that  it's have a 25% or so chance of having a quick 
channel change but it doesn't seem like it.

Regards,
Michal

On 23/04/2004, at 5:17 PM, Klaus Schmidinger wrote:

> Michal Dobrzynski wrote:
> > I am running VDR 1.3.6 with "Update Channels" set to "no" (if that
> > makes a difference).
> >
> > Regards,
> > Michal
> Well, then I guess it must be a driver issue.
>
> Klaus
>
> > On 23/04/2004, at 5:07 PM, Klaus Schmidinger wrote:
> >
> > > Michal Dobrzynski wrote:
> > > > Frankly I'd be overjoyed if I only had to wait 3 seconds at channel
> > > > change :/ I timed it with a stopwatch and it takes at LEAST 5 
> > > > seconds
> > > > and sometimes even 8 seconds.
> > > >
> > > > I'm sure it wasn't always this slow :/ (ie when I first started
> > > > dabbling). And it sure as hell was never this slow under Windows 
> > > > back
> > > > when I tried it.
> > > Which version of VDR (if any) are you using?
> > > If it is 1.2.x, have you applied the "autopid" patch?
> > > That one is known to slow down channel switching.
> > > Can you try VDR 1.3.6?
> > >
> > > Klaus
> > >
> > > > On 23/04/2004, at 4:38 PM, Adrian P Challinor wrote:
> > > >
> > > > > I understand the concerns here, but this delay also happens on
> > > > > commercial
> > > > > TV's. I have a fairly expensive Phillips TV with built in DVB-T
> > > > > receiver,
> > > > > and it takes at least three seconds to switch between digital
> > > > > channels.
> > > > > Analogue is instant.
> > > > >
> > > > > Is this something to do with DVB-T encoding?
> > > > >
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: linux-dvb-bounce@linuxtv.org
> > > > > > [mailto:linux-dvb-bounce@linuxtv.org]
> > > > > > On Behalf Of Juri Haberland
> > > > > > Sent: Thursday, April 22, 2004 11:08 PM
> > > > > > To: linux-dvb@linuxtv.org
> > > > > > Subject: [linux-dvb] Re: Channel change delay with DVB-T
> > > > > >
> > > > > > Prakash K. Cheemplavam wrote:
> > > > > > > Michal Dobrzynski wrote:
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > I asked this on the VDR mailing list and was redirected here.
> > > > > > > >
> > > > > > > > Is there any way to reduce the massive channel change delays? I 
> > > > > > > > am
> > > > > > > > running 2 DVB-T budget cards and one Full Featured DVB-S card 
> > > > > > > > for
> > > > > > output
> > > > > > > > and channel change times are quite disconcerting.
> > > > > > > >
> > > > > > > > Every time my parents change the channel they have to ask what's
> > > > > > > > wrong as the screen stays black for 4 or 5 seconds (last night 
> > > > > > > > it
> > > > > > > > even took 7 seconds a few times).
> > > > > > > Are you experiencing this with vdr or apps in general? I once had
> > > > > > > the problem with vdr, when I compiled a 1.2.x version on a NPTL
> > > > > > > enabled system. Using a NPTL disabled system, vdr tuned very 
> > > > > > > fast.
> > > > > > > I
> > > > > > > haven't treid vdr 1.3.x with NPTL, though.
> > > > > > I have such delays also with a DVB-T 1.3 premium card. Switching 
> > > > > > to
> > > > > > channels on the same frequency as the previous channel is in 
> > > > > > general
> > > > > > very fast, but switching to another frequency can take up to 
> > > > > > several
> > > > > > seconds until you get a stable picture.
> > > > > >
> > > > > > This is without NTPL, with Linux kernel 2.4.25, dvb-kernel from
> > > > > > 2004-04-13 and VDR 1.2.6 - so nothing fancy. With DVB driver from
> > > > > > the
> > > > > > DVB branch (aka the old driver) switching was a bit slower but
> > > > > > reliable.
> > > > > >
> > > > > > Cheers,
> > > > > > Juri
>
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