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

[Martin Lambers]

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

bino-test-mjpeg-mode.patch
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