[linux-dvb] cx24116 & roll-off factor = auto

Alex Betis alex.betis at gmail.com
Fri Jan 23 20:51:53 CET 2009

On Fri, Jan 23, 2009 at 9:49 PM, Goga777 <goga777 at bk.ru> wrote:

> > > does support cx24116  the roll-off factor = auto ?
> >
> > no
> who should be care about of corrected roll-off factor which have to send to
> cx24116 - the drivers or user software ? does
> roll-off factor = 0,35 good for 99% dvb-s2 channels ?

Driver interface allows specifying AUTO value for most of the parameters.
User application has no idea what card is used and what driver is running.
Since there are other drivers/chipsets that can handle AUTO setting, I don't
see any reason why application should not use it.

For example, DVB-S uses only rolloff = 0.35, so if the driver knows that the
chip can't accept auto value, it should use 0.35 value by default in that

Beside all that, there is a bigger problem that pops up with cx24116 chips
using S2API.
When specifying AUTO value for any of the parameters the driver fails the
tuning, but the application knows nothing about it, so it thinks that
current received stream is from the new channel, while its not true.

> Goga
> _______________________________________________
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> For V4L/DVB development, please use instead linux-media at vger.kernel.org
> linux-dvb at linuxtv.org
> http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
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