Re: [RFC] Timestamps and V4L2

[Hans Verkuil <hverkuil@xs4all.nl>]

On Mon September 24 2012 22:11:50 Rémi Denis-Courmont wrote:
> Le dimanche 23 septembre 2012 14:43:42, Sakari Ailus a écrit :
> > > I think I like this idea best, it's relatively simple (even with adding
> > > support for reporting flags in VIDIOC_QUERYBUF) for the purpose.
> > > 
> > > If we ever need the clock selection API I would vote for an IOCTL.
> > > The controls API is a bad choice for something such fundamental as
> > > type of clock for buffer timestamping IMHO. Let's stop making the
> > > controls API a dumping ground for almost everything in V4L2! ;)
> > 
> > Why would the control API be worse than an IOCTL for choosing the type of
> > the timestamp? The control API after all has functionality for exactly for
> > this: this is an obvious menu control.
> > 
> > What comes to the nature of things that can be configured using controls
> > and what can be done using IOCTLs I see no difference. It's just a
> > mechanism. That's what traditional Unix APIs do in general: provide
> > mechanism, not a policy.
> 
> Seriously? Timestamp is _not_ a controllable hardware feature like brightness 
> or flash. Controls are meant to build user interface controls for interaction 
> with the user. Timestamp is _not_ something the user should control directly. 
> The application should figure out what it gets and what it needs.

Exactly. I agree completely.

Regards,

	Hans

> 
> Or why do you use STREAMON/STREAMOFF instead of a STREAM boolean control, eh?
> 
>