No preview / playback on linux

Bug
1

Hi, I compiled Shotcut 24.02.19 from source (on Gentoo) however I have no preview or playback.

When I load a video in I can get the player timeline to update with the length but pressing play does nothing.

screenshot_2024_06_08_02_05_48_2560x1422
screenshot_2024_06_08_02_05_48_2560x14222560×1422 80.4 KB

I have tried both “OpenGL” and “Software (mesa)” for the display methods and the results are the same.

When I launch Shotcut from the terminal the only error I see is:

libDeckLinkAPI.so: cannot open shared object file: No such file or directory

Everything after that is formats and codecs. Trying to import and play a video doesn’t report any errors or print anything in the terminal.

I have tried several different videos to no avail.

I have OpenGL working on this system and other software can play back videos just fine.

I’d love to troubleshoot this further but without any error messages or indication of what is going wrong I don’t know what to check or try.

2

You should try to run one of the Linux builds we provide on our download page. I am not interested to debug your build. I suspect you have an unexpected combination of versions of MLT and Qt dependencies. I have heard from other Gentoo users here getting it to work.

3

I figured it out.

I just pulled down the git repo and built that which has tons of debugging output. It turns out for some reason it can’t use pulse even though other software can.

This is what the git build printed:

[Error  ] <MLT> [consumer sdl2_audio] Failed to initialize SDL: Audio target 'pulseaudio' not available
[Error  ] <MLT> [consumer sdl2_audio] Failed to initialize SDL: Audio target 'pulseaudio' not available

Changing the audio output to ALSA fixed everything.

The debug output was very useful. Probably the Gentoo ebuild for Shotcut should retain the output or else troubleshooting is impossible.

Thank you for writing the software :grinning:

1 Like
4

Maybe there is a SDL audio backend piece that needs to be installed. In any case, in case others arrive here that audio APIs selection is in the Shotcut menu at Settings > Player > Audio API

5

Hey guys,

I had the same issue: Shutcut had Pulseaudio selected as a Audio backend, which I did not have installed as a part of libsdl2:

$ eix -I libsdl2
[I] media-libs/libsdl2
     Available versions:  2.28.5-r3^t 2.30.7-r1^t {X alsa aqua custom-cflags dbus doc fcitx gles1 gles2 +haptic ibus jack +joystick kms libsamplerate nas opengl oss pipewire pulseaudio sndio +sound static-libs test +threads udev +video vulkan wayland xscreensaver ABI_MIPS="n32 n64 o32" ABI_S390="32 64" ABI_X86="32 64 x32" CPU_FLAGS_PPC="altivec" CPU_FLAGS_X86="3dnow mmx sse sse2 sse3" VIDEO_CARDS="vc4"}
     Installed versions:  2.30.7-r1^t(09:42:58 PM 10/03/2024)(X alsa dbus gles2 haptic jack joystick kms opengl oss pipewire sound udev video vulkan wayland -aqua -custom-cflags -doc -fcitx -gles1 -ibus -libsamplerate -nas -pulseaudio -sndio -static-libs -test -xscreensaver ABI_MIPS="-n32 -n64 -o32" ABI_S390="-32 -64" ABI_X86="64 -32 -x32" CPU_FLAGS_PPC="-altivec" CPU_FLAGS_X86="mmx sse sse2 sse3 -3dnow")
     Homepage:            https://www.libsdl.org/
     Description:         Simple Direct Media Layer

Since I am running pipewire, I chose that one and it fixed the problem.

Thanks!