[linux-dvb] Writing DVB Software - couple questions

Wolfgang Wegner wolfgang at leila.ping.de
Wed Feb 23 00:39:54 CET 2005

On Wed, Feb 23, 2005 at 12:24:49AM +0100, Robert Schlabbach wrote:
> From: "Johannes Stezenbach" <js at linuxtv.org>
> > It's all undefined, as each demod hardware and driver has it's
> > own idea about them.
> Which is not good. Each driver should be required to norm its signal
> statistics, e.g. to a percentage. Only the driver can "know" how to do
> this, and if the driver doesn't do it, the application can't do it either.
> The Linux API should define exact value ranges for every statistic which
> every driver would be required to scale its hardware readings to. Then the
> statistics would actually be useful to applications for display purposes.

I totally agree here.
The values obtained may not be totally accurate (due to hardware tolerance),
but hey, this is not a measurement receiver we are building.

However, I would suggest to add the possibility to return some "MAX"
and "MIN" values from the driver (be it in an initialisation or together
with the value itself), because for some readings the range can be quite
different for different hardware, and IMHO it is better for the user
experience if (s)he can see if the limit is reached.

(Imagine a signal strength bar which never reaches the end value while
the frontend is already being overdriven...)

> Regards,
> --
> Robert Schlabbach


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