[gst-devel] 2x2 videowall pipeline

[David Balch]

Hi,

I've borrowed two cameras to give me a total of four, and it works :-)
Here's the pipeline:

gst-launch-0.10 v4l2src device=/dev/video0 !
video/x-raw-yuv,width=320,height=240,framerate=30/1 ! alpha ! queue !
videomixer name=mix ! ffmpegcolorspace ! \
  xvimagesink sync=false \
  v4l2src device=/dev/video1 !
video/x-raw-yuv,width=320,height=240,framerate=30/1 ! alpha ! videobox
left=-320 border-alpha=0 ! queue ! mix. \
  v4l2src device=/dev/video2 !
video/x-raw-yuv,width=320,height=240,framerate=30/1 ! alpha ! videobox
top=-240 border-alpha=0 ! queue ! mix. \
  v4l2src device=/dev/video3 !
video/x-raw-yuv,width=320,height=240,framerate=30/1 ! alpha ! videobox
left=-320 top=-240 border-alpha=0 ! queue ! mix.

Thanks again for your help :-)

There are some pictures on
http://occasionalrandoms.blogspot.com/2010/11/webcam-videowall.html.

Cheers,
Dave.

-- 
http://www.witchesband.com/

lch <david at balch.co.uk> wrote:
> Brilliant!
>
> This now works:
>
> gst-launch-0.10 v4l2src device=/dev/video0 !
> video/x-raw-yuv,width=320,height=240 ! alpha ! queue ! videomixer
> name=mix ! ffmpegcolorspace ! autovideosink \
>  videotestsrc pattern="green" ! video/x-raw-yuv,width=320,height=240
> ! alpha ! videobox left=-320 border-alpha=0 ! queue ! mix. \
>  videotestsrc pattern="blue" ! video/x-raw-yuv,width=320,height=240 !
> alpha ! videobox top=-240 border-alpha=0 ! queue ! mix. \
>  videotestsrc pattern="red" ! video/x-raw-yuv,width=320,height=240 !
> alpha ! videobox left=-320 top=-240 border-alpha=0 ! queue ! mix.
>
> Thanks Luciana! :-D
>
> I only have one cam with me at the moment, but hopefully I'll be able
> to add more without too much trouble. I'll let you know how I get
> on...
>
> Cheers,
> Dave.
>
> On 18 November 2010 16:06, Luciana Fujii Pontello
> <luciana at holoscopio.com> wrote:
>> On Thu, 2010-11-18 at 15:40 +0000, David Balch wrote:
>>> Hi,
>>
>>> gst-launch-0.10 v4l2src device=/dev/video0 !
>>> video/x-raw-yuv,width=320,height=240 ! queue ! videomixer name=mix !
>>> ffmpegcolorspace ! autovideosink \
>>>   videotestsrc pattern="green" ! video/x-raw-yuv,width=320,height=240
>>> ! videobox left=-320 border-alpha=0 ! ffmpegcolorspace ! queue ! mix.
>>> \
>>>   videotestsrc pattern="blue" ! video/x-raw-yuv,width=320,height=240 !
>>> videobox top=-240 border-alpha=0 ! ffmpegcolorspace ! queue ! mix. \
>>>   videotestsrc pattern="red" ! video/x-raw-yuv,width=320,height=240 !
>>> videobox left=-320 top=-240 border-alpha=0 ! ffmpegcolorspace ! queue
>>> ! mix.
>>>
>>> Unfortunately, the webcam doesn't actually show - it's corner is just
>>> black. (The webcam works with "gst-launch-0.10 v4l2src
>>> device=/dev/video0 ! video/x-raw-yuv,width=320,height=240 !
>>> autovideosink".)
>>
>> It seems like the property border-alpha is not working for you because
>> your video doesn't have alpha channel. Add an alpha element in every
>> video like this: videotestsrc pattern="blue" !
>> video/x-raw-yuv,width=320,height=240 ! alpha ! videobox top=-240
>> border-alpha=0 ! queue ! mix.
>>
>> (I think you can remove some of the colorspaces as well)
>>
>> Regards,
>>
>> Luciana Fujii
>>
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>
>
>
> --
> http://www.witchesband.com/
>



-- 
http://www.witchesband.com/