Re: [Bino-list] Possible to use two v4l2 inputs?

[Götz Dapp]

Hi Martin!

On 04/06/2012 10:22 AM, Martin Lambers wrote:
> Hi Goetz!
>
> On Fri, 06 Apr 2012 09:07:59 -0600, Goetz Dapp wrote:
> > On 04/06/2012 08:07 AM, Martin Lambers wrote:
> > > On Thu, 05 Apr 2012 15:24:59 -0600, Goetz Dapp wrote:
> > > > On 04/05/2012 12:10 PM, Martin Lambers wrote:
> > > > > Hi Goetz!
> > > > >
> > > > > On Thu, 05 Apr 2012 09:38:54 -0600, Goetz Dapp wrote:
> > > > > > I was wondering if it is at all possible to add two input devices
> > > > > > instead of one for 3D playback and designate them to one
> > > > > > perspective, i.e. /dev/video0 = left and /dev/video1 = right, or
> > > > > > something along those lines?
> > > > > There was an arbitrary limitation for a single device. I just
> > > > > removed this, and opening two devices for left/right now works, at
> > > > > least with the X11 grabber pseudo device (I don't have any v4l2
> > > > > devices).
> > > > >
> > > > > Can you test the latest version from the git repository?
> > > > >
> > > > > It should be possible to open the video devices from the command
> > > > > line: $ bino --device-frame-size=800x600 /dev/video0 /dev/video1
> > > > >
> > > > > If this works for you, I'll change the GUI dialog to allow this,
> > > > > too.
> > > > >
> > > > > > It would be awesome if it also were possible to manually adjust
> > > > > > some of the v4l2 control ids for these devices.
> > > > > Hm, we're going through FFmpeg to open v4l2 devices. What controls
> > > > > would you like to adjust? Sorry, I don't know much about v4l2...
> > > > >
> > > > > Martin
> > > > Hi Martin,
> > > >
> > > > thanks for your quick reply! I'll compile Bino from git tonight and
> > > > give it a shot.
> > > >
> > > > Regarding the v4l2 controls, I am not even sure if that is doable
> > > > through ffmpeg. I am using a camera that has an autofocus
> > > > (V4L2_CID_FOCUS_AUTO) and auto white balance feature
> > > > (V4L2_CID_AUTO_WHITE_BALANCE), which sometimes messes up a video
> > > > during recording. There are other controls, too, that might be
> > > > interesting for my setup. I was thinking about presetting it, and
> > > > then turn it off, hence my question about the controls.
> > > FFmpeg does not seem to support these advanced controls, so I'm
> > > afraid we cannot easily add support for them to Bino. Isn't there
> > > some V4L2 application that allows to tweak all these things while
> > > an application uses the device?
> > >
> > > Martin
> > Hi Martin,
> >
> > thanks, that's what I suspected. I compiled bino last night and the
> > two input work! The resolution is limited to 800x600, I suspect that's
> > because of bandwidth issues. Do you know if ffmpeg supports
> > controlling the input data type / chroma, i.e. MJPG, which the camera
> > can run natively? When I use cvlc and set the v4l2-chroma to MJPG it
> > supports two cameras as 1280x800.
> This seems to be supported by FFmpeg, but I'm not sure how to use it.
> Can you add the following to line 815 in src/media_object.cpp?
> 'av_dict_set(&iparams, "input_format", "mjpeg", 0);'
> (Or apply the attached patch.)
>
> Does this work?
>
> If so, I can add a command line and GUI option "request mjpeg format"
> or similar.
>
> Martin
Works like a charm! Sweet! Thanks so much!

Best,
Goetz