Qt5: spinnies only spin when >1 deck is playing when using CPU waveform renderer with Ubuntu 18.04 Bionic

[Bernd Binder]

Since beta 2.2/qt5 (not in 2.1.4/qt4) the spinnys do not work proper under Ubuntu 18.04 (!!not under 16.04!!)

In my mixxx-development-environment i have two machines, one big box with Ubuntu mate 16.04 and a lenovo thinkpad edge 15 (TP) with ubuntu 18.04 bionic. The bug i mean only happens on the TP with bionic.

- Mostly the spinnys load a cover only, if a second deck has a track loaded. Curiously sometimes randomly a cover is loaded in the spinny.
- Then, when covers are loaded in both spinnys, they are spinning only if both decks are playing. if one deck stop playing - and it doesn't matter which one - both spinnys are stop spinning.
- When touching one Wheel for scratching, also both spinnys stop spinning.
When switching from big spinnys to normal, the behavior is the same.

In Ubuntu 16.04 i have not this behavior and i have there the same mixxx-releases with the same midi-mappings running. There are all spinnys work as well as they should, also the new big spinnys. So i think this is a bug in relation on ubuntu 18.04 bionic.

[Be (be.ing)]

Are you compiling Mixxx yourself or are you using the packages from the PPA? What GPU (graphics card) are you using on each computer? If you use an nVidia GPU, are you using nVidia's proprietary driver?

If you're lucky, maybe this will be fixed by switching from QGLWidget to QOpenGLWidget (Bug #1687937).

Ubuntu 18.04 has Qt 5.9.5, which is a bit outdated. Perhaps there is an underlying bug in Qt which has been fixed since then?

[Bernd Binder (banad)]

I use(ed) the latest beta-releases (now: 2.2 r6590) from the PPA. But this behavior i watched since qt5 in my own compiled test-versions also.

There is no Nvidia CPU on start. On the Thinkpad with 18.04 works with the build-in GPU from Intel:
Intel Corporation Core Processor Integrated Graphics Controller (rev 02)

On the other machine with 16.04, a AMD/ATI:
Advanced Micro Devices, Inc. [AMD/ATI] Caicos [Radeon HD 6450/7450/8450 / R5 230 OEM]

So i can only hope, the fix by switching to QOpenGLWidget will do it. I stay tuned.

[Be (be.ing)]

I doubt this will make a difference, but could you test the different options for the waveform renderer in the Waveforms section of the preferences with your computer running Ubuntu 18.04? Does this bug happen with all of them?

[Bernd Binder (banad)]

Be, you are right, it must have to do with the rendering of the waveforms. Now i know a bit more!! In order your instructions i tested in r6594 it with different preferences.

The bug comes up, when i render the waveforms with RGB, HSV or VsyncTest
video: https://www.binder-pro.de/download/mixxx/screen/Bildschirmaufnahme_2018-10-25_10:26:16_konf.mp4

I can't watch the bug, when i render the waveforms with Simple-QT(GL), Filtered-QT(GL), Simple(GL)
Filtered(GL), Filtered(GLSL), RGB(GL), RGB(GLSL)
video: https://www.binder-pro.de/download/mixxx/screen/Bildschirmaufnahme_2018-10-25_09:46:04_konf.mp4

In VsyncTest is only a red bar flickering, instead of showing a waveform, but i think this is another story.

[Be (be.ing)]

That's interesting. Thank you for making the videos. I am marking this as Low priority considering that the workaround is easy.

I am guessing that even though the spinnies are QGLWidget subclasses, somehow they are not getting rendered with OpenGL unless one of the OpenGL waveform renderers is also used. That doesn't explain why this bug is occurring when CPU rendering is used though.

[ronso0 (ronso0)]

Support for Bionic Beaver 18.04 was dropped, Qt 5.12 is required

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/9481