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

[Michal Dobrzynski]

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: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]
On Behalf Of Juri Haberland
Sent: Thursday, April 22, 2004 11:08 PM
To: [EMAIL PROTECTED]
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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