awalls at radix
Mar 27, 2009, 2:37 PM
Post #12 of 13
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On Fri, 2009-03-27 at 21:30 +0100, Hans Verkuil wrote:
> On Friday 27 March 2009 20:19:29 Martin Dauskardt wrote:
> > Hans Verkuil wrote:
> > > I'm not sure what the problem is. An application shouldn't have to care
> > > about whether an input is a S-Video, Composite or something else. The
> > > only exception is if it is a Tuner input, since that means that tuner
> > > related ioctls are available. Other than that, these names are just for
> > > the user.
> >
> > I think an application should make things as much easy as possible for
> > the user. Let's suppose a user wants to record from his VHS-machine and
> > plugs the cable into the S-Video connector. Now he wants to switch to the
> > appropriate input. Do you suggest that he should first detect the number
> > of the right input by using v4l2-ctl ? Or testing different input
> > numbers by try-and-error? It is not the job of the user to know the input
> > number of each connector.
> > Using the pvrinput plugin, the user simply chooses "S-Video", and the
> > plugin sets the input to the appropriate input number - no matter if it
> > is a PVR350 (input 1) or PVRUSB2 (input 2)
> > But things would be easier if we had a standard for naming the inputs.
>
> ???
>
> An application should call ENUMINPUT to enumerate all possible inputs and
> let the user choose between them. You present the name of each input as
> returned by ENUMINPUT to the user, and that maps to the input number (the
> index passed to ENUMINPUT). An application should not attempt to interpret
> these names since these names are entirely dependent on the hardware.
>
> If the pvrinput plugin has a hardcoded list of inputs (tuner, S-Video,
> Composite), then that's wrong. The simplest example would be ivtv where you
> can have multiple S-Video and Composite inputs if the user bought a add-on
> cable.
Right. The HVR-1600(MCE?) supports the same cable as the PVR-150MCE
used for additional S-Video, CVBS and Audio inputs - I happen to have
one of those cables. :)
Here's what the cx18 driver blurts out for inputs. Note, the "Name"
originates in the driver. (I suppose i8n is a problem.)
$ v4l2-ctl --list-inputs | grep -B1 Name
Input : 0
Name : Tuner 1
--
Input : 1
Name : S-Video 1
--
Input : 2
Name : Composite 1
--
Input : 3
Name : S-Video 2
--
Input : 4
Name : Composite 2
Regards,
Andy
> Newer hardware may have HDMI or Component inputs. Webcams only have
> a camera input, but a stereo webcam might have two camera inputs. Or the
> input names might correspond to connector labels on a backplate, etc. etc.
>
> Don't interpret the input names, just pass them on to the user and let the
> user choose which input he wants.
>
> Regards,
>
> Hans
>
> > > If you really need to switch to a tuner input to get the radio to work
> > > on ivtv, then that's an ivtv bug. Although according to Andy it works
> > > with cx18, so I'm surprised that it doesn't work with ivtv since cx18
> > > is derived from ivtv. Can you double-check this?
> >
> > You are right, simply opening the radio device works fine with ivtv.
> > I tried this also with pvrusb2 and discovered a problem:
> >
> > Mike Isely wrote:
> > >Remember that opening /dev/radioX still produces the correct result.
> > >That is enough for any V4L radio application to use the driver without
> > >change.
> >
> > Yes, opening the radio device works. The driver switches automatically to
> > input 3 (radio) and the tuner uses 62,5 Hz steps:
> >
> > linvdr:~# v4l2-ctl -T -d 0
> > Tuner:
> > Capabilities : 62.5 Hz stereo
> > Frequency range : 65.0 MHz - 108.0 MHz
> > Signal strength : 25%
> > Current audio mode : bilingual
> > Available subchannels: stereo
> > linvdr:~# v4l2-ctl --get-input -d 0
> > Video input : 3 (radio)
> >
> > But after closing the radio device, these settings still exist. The
> > result is, that tuning to a TV station does not work. I also checked this
> > with v4l2-ctl: v4l2-ctl -f 280.25 -d 0 gives no error (but also reports
> > no success).
> >
> > To be able to tune to a TV frequency I must first set the input to 0:
> >
> > linvdr:~# v4l2-ctl -T -d 0
> > Tuner:
> > Capabilities : 62.5 Hz stereo
> > Frequency range : 65.0 MHz - 108.0 MHz
> > Signal strength : 25%
> > Current audio mode : bilingual
> > Available subchannels: mono
> > linvdr:~# v4l2-ctl --set-input 0 -d 0
> > Video input set to 0 (television)
> > linvdr:~# v4l2-ctl -f 280.25 -d 0
> > Frequency set to 4484 (280.250000 MHz)
> > linvdr:~# v4l2-ctl -T -d 0
> > Tuner:
> > Capabilities : 62.5 kHz multi-standard stereo lang1 lang2
> > Frequency range : 44.0 MHz - 958.0 MHz
> > Signal strength : 99%
> > Current audio mode : bilingual
> > Available subchannels: stereo
> >
> > Is this a problem of the application (both v4l2-ctl and pvrinput-plugin),
> > or should the driver switch to the previous input (as it was before
> > opening the radio) after closing the radio device ?
> >
> > Greets,
> > Martin
> >
> > _______________________________________________
> > ivtv-devel mailing list
> > ivtv-devel [at] ivtvdriver
> > http://ivtvdriver.org/mailman/listinfo/ivtv-devel
>
>
>
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