On Saturday 20 March 2010 14:51:44 Chicken Shack wrote:
> Am Samstag, den 20.03.2010, 13:37 +0100 schrieb Hans Verkuil:
> > On Saturday 20 March 2010 13:17:15 Chicken Shack wrote:
> > > Am Samstag, den 20.03.2010, 10:21 +0100 schrieb Hans Verkuil:
> > > > Hi all!
> > > >
> > > > The second phase that needs to be done to remove the v4l1 support from
> > > > the
> > > > kernel is that libv4l1 should replace the v4l1-compat code from the
> > > > kernel.
> > > >
> > > > I do not know how complete the libv4l1 code is right now. I would like
> > > > to
> > > > know in particular whether the VIDIOCGMBUF/mmap behavior can be faked in
> > > > libv4l1 if drivers do not support the cgmbuf vidioc call.
> > > >
> > > > In principle libv4l1 should allow V4L1 apps to run fine with V4L2
> > > > drivers.
> > > > That will also solve the problem of embedded device vendors running new
> > > > kernels with old V4L1 applications. They just need to use libv4l1.
> > > >
> > > > The third phase that can be done in parallel is to convert V4L1-only
> > > > apps.
> > > > I strongly suspect that any apps that are V4L1-only are also
> > > > unmaintained.
> > > > We have discussed before that we should set up git repositories for such
> > > > tools (xawtv being one of the more prominent apps since it contains
> > > > several
> > > > v4l1-only console apps). Once we have maintainership, then we can
> > > > convert
> > > > these tools to v4l2 and distros and other interested parties have a
> > > > place
> > > > to send patches to.
> > > >
> > > > I'm afraid that it is unlikely that anyone will do that work for us, so
> > > > it's
> > > > probably best just to bite the bullet and do it ourselves.
> > > >
> > > > Regards,
> > > >
> > > > Hans
> > > >
> > >
> > > Hello Hans,
> > >
> > > I haven't followed your discussion so far (sorry!).
> > > I got a trivial question:
> > >
> > > I run a Miro PCTV pro (stereo) on one of my machines.
> > > It needs "simple tuner transport" / "TDA 9885/6/7 analog IF
> > > demodulator", Micronas msp3400 for Stereo tone PLUS v4l1 compat layer as
> > > kernel options to run / to be usable at all.
> >
> > That's the V4L2 bttv driver. What app are you using with this card?
>
> Should rather be:
> What apps are you using (Plural mode)?
>
> One big mess somehow.
>
> 1. The only one that runs is tvtime. But with tvtime I cannot record
> streams.
> 2. Then I have tested zapping, which is a gnome app.
> No matter if I start it without parameters or with parameter
> LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so (it's a Debian system), channel
> switching is simply impossible. Version is 0.10cvs6.
zapping is definitely V4L2 aware. Make sure it is not trying to use V4L1.
>
> Well, and the biggest pest are the radio apps:
> 1. Running gnomeradio the channel scanner does not find anything and I
> cannot hear anything (independent from starting mode - with or without
> parameters).
Which gnomeradio version are you using? 1.8 seems to support V4L2.
Again, make sure it isn't selecting V4L1 instead of V4L2.
> 2. Maybe Gerd's "radio" solves it, but in that case recording is
> unclear, as it is a rather primitive GUI without recording function
> implied.
>
> > >
> > > Can you make sure that this card will still be usable after your v4l1
> > > removal activities are finished?
> >
> > You can easily test this by turning off the compat layer in the kernel
> > config. You should still be able to use your v4l1 app by using
> > LD_PRELOAD=/usr/lib/v4l1compat.so.
>
> Hmmm. See above. If I used the parametry in a wrong way please tell me.
>
> > > In other words: What happens to this v4l1 compat code which is obviously
> > > necessary for this (and other) card(s) to run?
> > >
> > > That's it what I haven't understood right now, so could you please be
> > > kind enough to explain that with a couple of words?
> > >
> > > Thanks!
> > >
> > > CS
> > >
> > > P. S.: If you make your decision to host xawtv and other apps please do
> > > not merge hybrid applications (i. e. apps made for DVB and analogue
> > > devices) as you can find them in the xawtv 4.0 pre alpha code for
> > > example in analogue trees.
> > > Rather establish extra trees for hybrid applications please.
> >
> > These apps will each get their own tree.
> >
> > Regards,
> >
> > Hans
>
> This sounds excellent :)
>
> Best Regards
>
> Uwe
>
> P. S.: So if I take you right the kernel compat module function does not
> hit or point to the driver itself, but rather to the application layer?
> Not easy to anticipate this as a picture in my head......
The driver is V4L2, but the kernel compat layer can translate V4L1 calls
to V4L2 calls. The libv4l1compat can do the same, but now in userspace
instead of kernelspace. What I don't really know is whether libv4l1compat
can completely replace the kernel compat layer.
Of course, the best solution is to convert the V4L1 apps to using V4L2.
Note that it would be useful if you can try to debug these apps a bit. I
would not at all be surprised if you are looking at application bugs rather
than kernel bugs.
Regards,
Hans
--
Hans Verkuil - video4linux developer - sponsored by TANDBERG
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