[Fedora 40] Video Player Example crash when using Mouse to change Speed

[PaoloMolinari]

The Video Player Example crash when using the mouse to change the speed of reproduction in Fedora 40. The error is the following:

(videoPlayerExample:662459): GStreamer-CRITICAL **: 10:49:11.098: gst_segment_position_from_running_time_full: assertion 'segment->format == format' failed

When using the keyboard works fine.

I realized now that the problem is not exclusive of "0.12.1 Release Push", but also of the version 0.12.0 that I have been using normally.

the gstreamer version is:

$ gst-launch-1.0 --version
gst-launch-1.0 version 1.24.11
GStreamer 1.24.11

thanks

[artificiel]

confirmed on Arch Linux with examples/video/videoPlayerExample; the problem is that 2 mouse events are processed with 1 video update, and that throws GST into a solid freeze (Release and Debug).

solved by adding a guard bool preventing more than 1 speed change per video update, but it seems like a bit of a hack and maybe it's circumventing the real problem, or maybe there's a solution at a lower level -- someone with better GST familiarity should look/confirm.

(also: negative speeds don't work, but language in the OF video/GST sources imply that reverse direction is expected to be working. another question for the same GST-familiar person!)

gst-launch-1.0 version 1.24.12
GStreamer 1.24.12

[ofTheo]

Thanks @artificiel - a PR for this would be helpful even if it's a temp fix.
I don't see this issue on Linux Mint, but can test any proposed fix to make sure it works on Ubuntu/Mint too

[artificiel]

@ofTheo OK i will do so, but then i will also dig just a little to bit into GST.

0. what is your version of GST?

1. on Mint with OF_LOG_VERBOSE do you get a thick console stream of (this is what i get over 1 frame here):

[verbose] ofGstUtils: getPosition(): couldn't query position
[verbose] ofGstUtils: gstHandleMessage(): unhandled message from app_sink
[verbose] ofGstUtils: getPosition(): couldn't query position
[verbose] ofGstUtils: gstHandleMessage(): unhandled message from app_sink
[verbose] ofGstUtils: gstHandleMessage(): async done
[verbose] ofGstUtils: gstHandleMessage(): end of the stream

2. does the negative (left side of screen) work for you and make the movie play backwards? (here it just stays on current frame)

3. what happens if you double the line 416 of ofGstVideoPlayer.h so it looks like this (trying to trigger the bug on your side in case your mouse events are handled differently):

void ofGstVideoPlayer::setSpeed(float speed){
	videoUtils.setSpeed(speed);
	videoUtils.setSpeed(speed);
} 

[ofTheo]

@artificiel my GST version is:
GStreamer Core Library version 1.16.3

The only error I get is an occasional:

[ error ] ofGstUtils: setSpeed(): couldn't query position

So seems like an issue with newer gstreamer version.
Backwards playback works for me.

gsttest.mp4

[ofTheo]

void ofGstVideoPlayer::setSpeed(float speed){
	videoUtils.setSpeed(speed);
	videoUtils.setSpeed(speed);
} 

This does nothing different on my end.

[artificiel]

ok #8344 is the simple fix. tried a machine with 1.20 and same crashy behaviour, but different backwards speed behaviour. it sometimes works, sometimes it stays on a frame forever. i'll make a different issue for that.

[artificiel]

@PaoloMolinari please test the fix and if your crashes are resolved, close this issue.

If you have weird behaviour with négative speed please document it and open another issue for that

[PaoloMolinari]

@artificiel It does fix the crashes when using the mouse (positive or negative speed). However, it does not play backwards with negative speed. I will open another issue.

[ofTheo]

closed by #8344