Cannot play a 4K mkv content with v4l2h265dec plugin

Nicolas Dufresne nicolas at
Mon Mar 22 18:50:19 UTC 2021

Le lundi 22 mars 2021 à 05:15 -0500, karimchtx a écrit :
> Hi, I'm currently trying to play a 4K content on an IMX8 based board, an
> apalis
> imx8. I planed to use the v4l2h265dec decoder, as at first glance, the imx
> vpudec plugin is not available for this processor, though it's supported on
> imx8m and mx8mm. I've designed the following pipeline: root at apalis-imx8:~#
> XDG_RUNTIME_DIR=/run/user/0 gst-launch-1.0 -v filesrc
> location=/media/sda1/4K_content.2160p.UHD.BLURAY.REMUX.HDR.HEVC.x265.mkv !
> matroskademux name=d d. ! queue ! h265parse ! v4l2h265dec ! waylandsink
> Unfortunately, I systematicaly get the following error, whatever I try to
> change
> the pipeline.
>  streaming stopped, reason not-negotiated (-4) Execution ended after
> 0:00:00.131678311 Setting pipeline to PAUSED ... Setting pipeline to READY ...
> Setting pipeline to NULL ... Total showed frames (0), playing for
> (0:00:00.132085050), fps (0.000).
> Is there something obviously wrong in my pipeline ? Thanks for your feedback.
> K.

Not negotiation is a common pipeline error. It means what two elements in your
pipeline could not negotiate their format. It does not say which one though, but
I suspect the v4l2h265dec ! waylandsink is the culprit. You need your compositor
to support the pixel format produced by your decoder.

To confirm this, add videoconvert to see if that make it display something,
don't expect 4K if software video conversion is taking place. Next step, inspect
the caps, you can use -v to see the caps being set on each pads. The video/x-raw
caps will have formats which will help you. You can also use weston-info to list
the format supported by your compositor. Remember that this is still downstream
and NXP carries a large amount of patches accross gstreamer, weston, mesa etc.
So you may need to use these patches if you aren't using their vendor OS.

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