[linux-dvb] TDA10046H very slow to tune

hermann pitton hermann-pitton at arcor.de
Wed Aug 16 00:58:18 CEST 2006


Am Dienstag, den 15.08.2006, 21:11 +0200 schrieb Hartmut Hackmann:
> Hi, Barry
> 
> Barry Scott wrote:
> > I'm noticing that the KWORLD DVB-T 220 with the
> > TDA10046H tuner is very slow to tune 2 to 5 seconds.
> > Cards like the AverMedia 771 tune in less then a second.
> > 
> > Is this a problem with the driver or the chip?
> > 
> > Barry
> > 
> This is not normal, do you use a recent version of driver and firmware?
> The tuning takes about 0.5 seconds. With good signals, the TDA10046
> locks within a second. You need to add the time for the DVB application
> to fill its buffers and to find an I-frame. This is longer but the same
> for all cards.
> But: the first lock in a session (open dvb device) always takes longer
> becase the chips need to recover from sleep mode, check and download the
> firmware and determine some parameters. This is partly intention, partly
> chip behaviour.
> 
> If the lock always takes longer, this might be due to poor signal quality.
> Updating the firmware might help.
> There also is one special issue with the TDA8275a silicon tuner: Due to
> its pinciple, it is sensitive to strong transmitters on another channel.
> Classic tuner "cans" handle this better.

Hi,

at least I can confirm what Hartmut just outlined even on a tda8275a.

You should be able to see it on xawtv4 that it not caused by tuning
delay, but by buffering, for the price to have some artifacts in the
very beginning.

Cheers,
Hermann





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