libavutil.so.60 crashes with a libcuda.so.1 error

[Boria138]

I wanted to add sound to my Pyside app using Qt Multimedia and QAudioOutput, but I ended up getting a crash: Qt Multimedia ffmpeg plugin → av_hwdevice_ctx_create → cuCtxCreate_v2 → libcuda.so.1 → SEGFAULT

Links for troubleshooting

https://git.linux-gaming.ru/Linux-Gaming/PortProtonQt/actions/runs/2978/jobs/5564

https://git.linux-gaming.ru/Linux-Gaming/PortProtonQt/commit/55a0a158c87e56cbf366dd802ccb4b189659423c

[Samueru-sama]

Run the appimage with APPIMAGE_DEBUG=1 and send the debug file.

Loading libcuda.so.1 cannot cause a crash, if that was the case, this crash would also happen with the ffmpeg package on archlinux for nvidia users.

[Boria138]

Run the appimage with APPIMAGE_DEBUG=1 and send the debug file.

Loading libcuda.so.1 cannot cause a crash, if that was the case, this crash would also happen with the ffmpeg package on archlinux for nvidia users.

PortProtonQt-r1968.55a0a158-anylinux-x86_64.AppImage-debug.log

libcuda is included here, so I assume my analysis is correct, and this error most likely occurs because ALT Linux includes three drivers right out of the box to support all graphics cards, other distributions don’t have this. For clarification, you can check out my PR on runimage—there are comments throughout explaining exactly what’s different in ALT: VHSgunzo/runimage#21

[Boria138]

Judging by the code, my guess was wrong: CUDA isn't used from the system, but is instead loaded from within the AppImage, which in turn is loaded during the build from Arch, since Arch has driver 596, and I have a 1060 that requires driver 580—the 596 causes it to crash.

[Boria138]

I fixed it with cuda symlinks and everything started working, but there's no sound—I'm getting a “pw_stream_connect failed” error. I think qtmultimedia needs to deploy PulseAudio and Pipewire.

[Samueru-sama]

The nvidia libraries must always come from the host, those cannot ever be bundled just in case, since they need a matching kernel module.

If libcuda.so.1 is present in the host but you don't have an nvidia gpu, and ffmpeg still goes and loads it and this causes a crash, that is not a bug on our end, this bug would manifest with the same ffmpeg version anywhere else.

For reference yuzu (and all forks) will always try to load libcuda.so.1 when it plays videos, I never saw this causing issues for non nvidia users.

[Samueru-sama]

I think qtmultimedia needs to deploy PulseAudio and Pipewire.

99% of the time pulseaudio will be included as a transitive dependency of something.

but if that is not the case, set DEPLOY_PULSE=1

Pipewire rarely needs to be deployed, in fact we often overdeploy it.

[Boria138]

I think qtmultimedia needs to deploy PulseAudio and Pipewire.

99% of the time pulseaudio will be included as a transitive dependency of something.

but if that is not the case, set DEPLOY_PULSE=1

Pipewire rarely needs to be deployed, in fact we often overdeploy it.

I fixed both issues like this:
SHARUN_EXTRA_LIBRARY_PATH=/etc/libnvidiacurrent

This tells Sharun where CUDA is located—a quirk of the ALT package. I submitted a pull request, but it’s most likely not needed: #750

And QT_AUDIO_BACKEND=pulseaudio—without it, there’s no sound in the app; for some reason, the Pipewire backend refuses to work

[Samueru-sama]

This tells Sharun where CUDA is located—a quirk of the ALT package. I submitted a pull request, but it’s most likely not needed: #750

#750 (comment)

And QT_AUDIO_BACKEND=pulseaudio—without it, there’s no sound in the app; for some reason, the Pipewire backend refuses to work

This can happen if libpipewire is bundled but not all of pipewire-audio.

SDL actually had this bug, see libsdl-org/SDL#15924

[Samueru-sama]

I eventually made sure to always patch away the libpipewire string from libs and bins when something is deployed without pipewire at all.

But this doesn't work for cases where libpipewire is added but pipewire-audio is missing from the runner, in that case nothing gets patched.

[Boria138]

This can happen if libpipewire is bundled but not all of pipewire-audio.

SDL actually had this bug, see libsdl-org/SDL#15924

Apparently, this is because qt6-multimedia has both libpulse and pipewire in its dependencies, so pipewire is pulled in as an automatic dependency.

[Samueru-sama]

This can happen if libpipewire is bundled but not all of pipewire-audio.
SDL actually had this bug, see libsdl-org/SDL#15924

Apparently, this is because qt6-multimedia has both libpulse and pipewire in its dependencies, so pipewire is pulled in as an automatic dependency.

Yeah in that case if the appimage ends up with libpipewire you will have to install pipewire-audio in the runner so that it correctly gets deployed.

Or option B is running pacman -Rdd libpipewire before deploying and see if stuff works.

[Boria138]

#750 (comment)

pkgforge-dev/Anylinux-sharun#6

As I mentioned earlier, in theory it would be better to run ldconfig -p and use its output to specify the folder, but I didn't want to make major changes to the code, so I just added the folder

[Samueru-sama]

As I mentioned earlier, in theory it would be better to run ldconfig -p and use its output to specify the folder, but I didn't want to make major changes to the code, so I just added the folder

ldconfig -p is unreliable and a major source of headaches. Good thing musl got rid of it fully.