Arch Linux

dalu

Member

Registered: 2014-04-16

Posts: 82

VLC 100% CPU of 1 core when listening to a MPEGA DVB stream

I have a Fritz Repeater DVB-C to IP device.
(https://www.amazon.de/AVM-Repeater-Dual … B00N7ZYETI)

Hardware Soundblaster Z.

09:00.0 Audio device: Creative Labs CA0132 Sound Core3D [Sound Blaster Recon3D / Z-Series / Sound BlasterX AE-5 Plus] (rev 01)
	Subsystem: Creative Labs SB1570 SB Audigy Fx
	Flags: bus master, fast devsel, latency 0, IRQ 16
	Memory at 84304000 (64-bit, non-prefetchable) [size=16K]
	Memory at 84300000 (64-bit, non-prefetchable) [size=16K]
	Capabilities: [40] Power Management version 3
	Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+
	Capabilities: [70] Express Endpoint, MSI 00
	Capabilities: [100] Advanced Error Reporting
	Capabilities: [140] Virtual Channel
	Capabilities: [170] Device Serial Number 00-00-00-00-00-00-00-00
	Capabilities: [180] Power Budgeting <?>
	Kernel driver in use: snd_hda_intel
	Kernel modules: snd_hda_intel

It exports radio channels in a m3u playlist.
Example entry

#EXTINF:0,Dlf
#EXTVLCOPT:network-caching=1000
rtsp://192.168.20.11:554/?avm=1&freq=274&bw=8&msys=dvbc&mtype=256qam&sr=6900&specinv=1&pids=0,16,17,18,20,800,810,850

1 core of my i9-14900k cpu is always on 100% usage, checked with top, htop, gnome system monitor, kde system monitor.

I have installed Fedora Workstation 39 in Virtualbox, and VLC there via Flatpak. Output Analog Surround 5.1.
And I'm playing the same m3u playlist there, which uses barely any resources. Output Analog Stereo.
Under Windows 10, the same version VLC, 64bit build, 3.0.20, is also using barely any resources when playing this playlist. Output 5.1.

So that means that it's an Arch-specific problem.

The question is, why?

I'm running cinnamon with pulseaudio on x11.
(Different topic, but wayland is stuck at 1920x1080 resolution on my 3840x2160 monitor, so I'm not using that)
It doesn't matter which sink I use. 100% cpu usage of 1 core.

I can copy specific streams out of the playlist and play those with ffplay.
The result is NO 100% cpu usage of 1 core, but normal low resource usage.
And that's with visualization enabled.
For whatever reason no other player can deal with this playlist so I'm stuck with VLC if I'd like to listen to DVB radio over IP.

I don't know where to even start debugging this.
FWIW VLC on arch has always been problematic. Buffer underruns, choppy playback.
I had to install kodi to watch TV streams from the same device without interruption.

I did remove all config files from VLC and the effect was the same, 100% cpu usage of 1 core.
journalctl has 0.
when started on the cli, there's 0.

I'll try downloading the PKGBUILD and doing an -O3 -march=native -mtune=native build.
But I don't think it's CPU optimizations.
It's some thread that does something it shouldn't.
I have aur/libva-nvidia-driver-git installed, but I also have extra/libvdpau and multilib/lib32-libvdpau installed.
LIBVA_DRIVER_NAME=nvidia

dalu

Member

Registered: 2014-04-16

Posts: 82

Re: VLC 100% CPU of 1 core when listening to a MPEGA DVB stream

I have rebuilt vlc (https://archlinux.org/packages/extra/x86_64/vlc/)
with yay -Bi
and -O3 -march=native -mtune=native
and the cpu usage issue went away!

I had to

pacman -Rdd ffmpeg lua52

and build, then

pacman -Sd ffmpeg lua52

after the build to successfully build.

So, idk.
Now what?
Create a bug report? I can't, because my account credentials are no longer recognized, since it's using keycloak now apparently and the accounts were never migrated. GOOD JOB!

Last edited by dalu (2023-12-03 15:05:27)