On Saturday 25 July 2009 15:25:21 Eduardo Valentin wrote:
> On Sat, Jul 25, 2009 at 03:33:55PM +0200, ext Hans Verkuil wrote:
> > On Saturday 25 July 2009 15:29:38 ext-eero.nurkk...@nokia.com wrote:
> > >
> > > > I'm surprised at these MAX string lengths. Looking at the RDS standard
> > > > it
> > > > seems that the max length for the PS_NAME is 8 and for RADIO_TEXT it is
> > > > either 32 (2A group) or 64 (2B group). I don't know which group the
> > > > si4713
> > > > uses.
> > > >
> > > > Can you clarify how this is used?
> > > >
> > > > Regards,
> > > >
> > > > Hans
> > >
> > > Well, PS_NAME can be 8 x n, but only 8 bytes are shown at once...
> > > so it keeps 'scrolling', or changes periodically. There's even commercial
> > > radio stations that do so.
> >
> > And I'm assuming that the same is true for radio text. However, this
> > behavior
> > contradicts the control description in the spec, so that should be
> > clarified.
>
> Yes, I'll add a comment explaining this for those defines.
Another question: what happens if I give a string that's e.g. 10 characters
long? What will happen then?
If the string must be exactly 8 x n long, then I think that it is a good idea
to start using the 'step' value of v4l2_queryctrl: this can be used to tell
the application that string lengths should be a multiple of the step value.
I've toyed with that idea before but I couldn't think of a good use case,
but this might be it.
Regards,
Hans
--
Hans Verkuil - video4linux developer - sponsored by TANDBERG Telecom
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