[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.


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.


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