Sound distorted with VLC 2.1.x and ALSA

[Naxi]

Hello,
all 2.1.x versions produce horrible distorted loud sound if volume is changed wthin VLC. It doesn't make any difference if volume is higher or lower. As soon as the level is different from 100% sound is (I presume) maximum level and horribly distorted.

I needed to reset the settings after upgrade to get sound at all so this is done.

The machine is running gentoo with kernel 3.12.5, KDE and ALSA with a ASUS DX surround sound card.

P.S. the USE-Flags:

Code: Select all

media-video/vlc USE="X a52 alsa avcodec avformat bluray cdda cddb dbus dts dvbpsi dvd encode ffmpeg flac gcrypt kde libnotify libsamplerate matroska mmx mp3 mpeg mtp ncurses ogg opengl png postproc qt4 samba sdl skins speex sse swscale taglib theora truetype udev upnp vaapi vcdx vorbis wma-fixed x264 xcb xml xv"

[Rémi Denis-Courmont]

This is fundamentally unavoidable if you do integer output on ALSA. You'd better use PulseAudio if you want to use the full volume scale.

[Naxi]

This is fundamentally unavoidable if you do integer output on ALSA. You'd better use PulseAudio if you want to use the full volume scale.

I understand but changing the volume in any way, even turning it down does trigger that effect. It does not happen on vlc < 2.1.x and makes vlc unusable.

[Rémi Denis-Courmont]

Uh, I think that bug was fixed in VLC 2.1.1.

[Naxi]

Uh, I think that bug was fixed in VLC 2.1.1.

Unfortunately it is not fixed. I checked with Versions 2.1.1 and 2.1.2 .

[Rémi Denis-Courmont]

It works fine here with ALSA and either signed-16 or float-32 output on VLC 2.1.1 and later.

[Naxi]

ok I am partly wrong. It does work with native 5.1 surround sources, but all 2.0 sources which have to be upmixed via alsa (because otherwise it sounds very strange) show the described behaviour. There seems to be some issues with vlc and soft-alsa-devices.
I'll try to see if pulseaudio does everything I need and try to switch. Maybe you can have a look whats wrong with alsa soft-devices in case pulseaudio does not fit my needs ?

[Naxi]

ok I am partly wrong. It does work with native 5.1 surround sources, but all 2.0 sources which have to be upmixed via alsa (because otherwise it sounds very strange) show the described behaviour. There seems to be some issues with vlc and soft-alsa-devices.
I'll try to see if pulseaudio does everything I need and try to switch. Maybe you can have a look whats wrong with alsa soft-devices in case pulseaudio does not fit my needs ?

Since I didn't find an option to edit my last post I reply to it..
Pulseaudio works fine so far but I lost one important thing: my room setup. I can't find a way to setup the channels relative levels. Maybe somebody here has a tip for me ?

[Rémi Denis-Courmont]

VLC does not support balancing, and balancing should be configured for the whole computer anyway. There should be PulseAudio GUIs for this, but you'd better check at PulseAudio-related venues...

[bernd_b]

I can't find a way to setup the channels relative levels. Maybe somebody here has a tip for me ?

Running pulse, I could adjust each channel with the help of the tool pavucontrol. Don't know if this is what you are looking for.

[Greenleon]

I can confirm, that this bug is still present in 2.1.2 when using multichannel output to ALSA - without pulse.

We run debian testing (jessie) on a Dell Optiplex 760 with a CA0106 card.
When starting playback audio works fine, but as soon as I change the volume, the volume goes to 100% and is horribly distorted. I did not find a ticket in the bugtracker.. should I open one?

[Greenleon]

I created a ticket for this issue: https://trac.videolan.org/vlc/ticket/11483#ticket