AW: Displaying camera not working

Fri Apr 27 09:17:53 UTC 2018

I intended to fix it later because this particular thing didn't seem to 
be the problem. But maybe I start with it today or on monday. I was 
aware of v4l2-compliance, thanks.

In the meantime, I have done some findings:

I used this command in my device:

gst-launch-1.0 v4l2src device=/dev/video1 ! 
video/x-raw,format=NV12,width=720,height=576 ! filesink 
location=raw_video.bin

Then, I transfered raw_video.bin to my computer and used this command:

gst-launch-1.0 filesrc location=raw_video.bin ! videoparse width=720 
height=576 format=GST_VIDEO_FORMAT_NV12 ! videoconvert ! autovideosink

This way, I can see the image OK, not only lot of lines of random 
colors. So I concluded that the problem in my device must be in 
videoconvert or in xvimagesink, not in the cameras driver.

My device is using an Allwinner A20 SoC. This SoC uses the framebuffer 
to output graphics, even using X11. So I installed fbdevsink plugin and 
tried this command:

gst-launch-1.0 v4l2src device=/dev/video1 ! 
video/x-raw,format=NV12,width=720,height=576 ! videoconvert ! fbdevsink 
sync=false

I can see the image OK. I still don't know if the problem is in 
videoconvert, in xvimagesink, or in both. However, I can't use fbdevsink 
because it interferes with X11, trying both of them to "take control" of 
the framebuffer. Any hint about what can I try to find out what's 
failing and how to solve it?

Also, I have another problem. Only one of every 7 buffers seems to be 
updated with a new frame, the other 6 remains with the first fame they 
captured at the beginning, so I have a video of the same sequence of 6 
frames repeating all time the same and one single frame that seems to be 
correct between each 6 frames sequence.

This problem could be related with the driver, but it's strange because 
with the demo program this didn't happen.

El 25/04/18 a las 15:26, Nicolas Dufresne escribió:
>
>
> Le mar. 24 avr. 2018 09:27, Iñigo Huguet <inigohuguet at fanamoel.com 
> <mailto:inigohuguet at fanamoel.com>> a écrit :
>
>     I don't have playbin2, but I do have playbin.
>
>     It doesn't work right now, I think it is because the driver doesn't
>     report correctly its available framesizes (width X height). That's
>     why I
>     had to specify them with video/x-raw width=720,height=576
>
>     There is any way to specify the framesize with playbin? If not, I
>     will
>     try to fix the driver.
>
>
> If that is an option for you, then it's best thing to do. By the way, 
> are you aware of the v4l2-compliance test ? This test, which is part 
> of v4l2-utils helps a lot to ensure your driver is usable across most 
> userapace.
>
>
>
>     El 24/04/18 a las 12:45, Bernhard Graaf escribió:
>     > Have you try to use playbin2 instead?
>     > Something like 'gst-launch-1.0 playbin2 uri=v4l2:///dev/video1'.
>     > If its works, have a look into the log and see what playbin2 had
>     done.
>     >
>     > Bernhard
>     >
>     > -----Ursprüngliche Nachricht-----
>     > Von: gstreamer-devel
>     [mailto:gstreamer-devel-bounces at lists.freedesktop.org
>     <mailto:gstreamer-devel-bounces at lists.freedesktop.org>]
>     > Im Auftrag von Iñigo Huguet
>     > Gesendet: Dienstag, 24. April 2018 11:13
>     > An: Antonio Ospite; gstreamer-devel at lists.freedesktop.org
>     <mailto:gstreamer-devel at lists.freedesktop.org>
>     > Betreff: Re: Displaying camera not working
>     >
>     > Hi.
>     >
>     > I have gotten one frame as you told me
>     >
>     > gst-launch-1.0 v4l2src num-buffers=1 device=/dev/video1 !
>     > video/x-raw,format=NV12,width=720,height=576 ! filesink
>     > location=raw_frame.bin
>     >
>     > Then, in my computer, I converted it to png:
>     >
>     > gst-launch-1.0 -v filesrc location=raw_frame.bin ! videoparse
>     width=720
>     > height=576 format=GST_VIDEO_FORMAT_NV12 ! videoconvert ! pngenc !
>     > filesink location=raw_frame.png
>     >
>     > I can see the .png image correctly, so it seems that the driver
>     outputs
>     > NV12. What can I try now? Maybe I need any additional plugin?
>     (I'm using
>     > a custom build using Buildroot so I don't have all plugins
>     installed)
>     >
>     > El 23/04/18 a las 17:09, Antonio Ospite escribió:
>     >> On Mon, 23 Apr 2018 16:26:42 +0200
>     >> Iñigo Huguet <inigohuguet at fanamoel.com
>     <mailto:inigohuguet at fanamoel.com>> wrote:
>     >>
>     >>> I have managed to solve a problem: it seems that the sprite
>     was not well
>     >>> reported by the driver (it said it was 1080 instead of 720).
>     Now I think
>     >>> it gives the correct values for a 720x576px NV12 frame: sprite
>     720, size
>     >>> 622080
>     >>>
>     >>> However, I still doesn't have a good output, and I don't know
>     what to do
>     >>> to find what's wrong (I have no previous experience with video nor
>     >>> gstreamer).
>     >>>
>     >>> With this pipeline: gst-launch-1.0 v4l2src device=/dev/video1 !
>     >>> video/x-raw,format=NV12,width=720,
>     >>> height=576 ! videoconvert ! xvimagesink sync=false
>     >>>
>     >>> I only get an output with very colorful lines (almost
>     horizontal lines).
>     >>>
>     >>> I attach the output of the driver and gstreamer with
>     >>> GST_DEBUG=*videosink*:6,*imagesink*:6,*v4l2*:6
>     >>>
>     >>> Any hint? Thanks!
>     >>>
>     >> If you cannot trust the driver to report the correct data
>     format (I am
>     >> thinking to the pixelformat in particular), then GStreamer
>     videoconvert
>     >> won't be able to use the caps in any meaningful way.
>     >>
>     >> You could analyze a raw frame to confirm that it's actually NV12.
>     >>
>     >> A sample pipeline which (hopefully) dumps one frame is:
>     >>
>     >>     gst-launch-1.0 v4l2src num-buffers=1 device=/dev/video1 !
>     filesink
>     > location=raw_frame.bin
>     >> Upload the raw data somewhere and maybe someone will take a look
>     >> if they have time.
>     >>
>     >> Ciao,
>     >>      Antonio
>     >>
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