Using Gstreamer Editing Services on a raspberry pi causes v4l2h264enc crash

[Vincent Achard]

Hello,

I am trying to find a way to cut a video file (h264/mp4), on a Raspberry Pi
4B, using Gstreamer and hardware acceleration.

I tried Gstreamer Editing Services (package ges-tools): you can reproduce
following these two steps:


   1.

   Creation of a video file (as you probably know the capsfilter for the
   encode level after the v4l2encoder is mandatory, more details about this
   follow below)


gst-launch-1.0 videotestsrc num-buffers=100 ! v4l2h264enc !
'video/x-h264,level=(string)3' ! h264parse ! mp4mux ! filesink
location=video.mp4



   1.

   Attempt to cut the video file using ges-launch


ges-launch-1.0 +clip video.mp4 inpoint=1 duration=1 -o out.mp4 -f
"video/quicktime:video/x-h264"

It fails at step 2 with errors in console and in the kernel:


   1.

   Stderr in console


ERROR from element v4l2h264enc0: Failed to process frame./>

Debugging info: ../sys/v4l2/gstv4l2videoenc.c(828):
gst_v4l2_video_enc_handle_frame ():
/GESPipeline:gespipeline0/GstEncodeBin:internal-encodebin/v4l2h264enc:v4l2h264enc0:

Maybe be due to not enough memory or failing driver


   1.

   Kernel error (from dmesg, pretty long: I only paste here the line in red)


…

[172098.718574] bcm2835-codec bcm2835-codec: bcm2835_codec_start_streaming:
Failed enabling i/p port, ret -3

…


I'm using the newest mainstream 32bits OS for the raspberry pi : Debian
version: 11 (bullseye)”, which I downloaded here:

https://www.raspberrypi.com/software/operating-systems/#raspberry-pi-os-32-bit

kernel version: 5.15 32bits,

Gstreamer version is 1.18.4.


I did some investigations (if I can call them as such…): testing
v4l2h264dec and v4l2h264enc elements both separately, and together, in
pipelines (all of the details are in the post linked above, not sure they
are useful for you).

Finding no solution, I asked on the raspberry pi forum on feb 21, 2023, but
no solution was offered there: (
https://forums.raspberrypi.com/viewtopic.php?t=347790).

To this date, the post got only one answer, by user “6by9” (labeled as
“Raspberry Pi Engineer & Forum Moderator”): according to this user, it
seems to be the same problem than the one posted in 2021 here:
https://forums.raspberrypi.com/viewtopic.php?f=38&t=305405. (i.e. : the
level chosen for the encode does not suit the kernel, the solution being a
capsfilter: 'video/x-h264,level=(string)3').

So it seems to be the same problem than in my case. Would you agree?

If so, is there any way to stick to using ges launch in order to reach my
goal (cutting a video on a Pi)? I suppose that would involve getting the
encoder to choose a level for the encode that suits the kernel/driver? I
understand that it is what solves the problem in a pipeline (the
'video/x-h264,level=(string)3' capsfilter after the encoder), but with
ges-launch I don’t know if it is possible to do something similar?

It’s okay with me if it means modifying some code in one of the packages
(ges, … v4l2h264enc, …) and rebuilding.

If there is no way to solve this issue using ges-launch, what are my other
options? (using Gstreamer would be nice of course). I imagined: a custom
plugin/element that drops frames, or creating an app and use seeking?

Thank you for at least reading up to this point!

Best regards
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