Lila: Move sounds only from left side

[bytbox]

When playing a game (and at other times), the move sound comes only from the left headphone. There's a caveat: this doesn't quite happen all of the time. Once in a while (~2% of the time), the sound makes it out of both headphones! I haven't found any consistent pattern.

This occurs on two different systems, both running firefox on archlinux under alsa. Neither system has any other sound problems.

This is an apparent duplicate of #4983, except this issue is a little less consistent.

My hunch is that this is not an issue with lichess itself, but rather with the interaction of the underlying sound library with firefox+alsa, along the lines of "for the first 0.5s after initializing the sound system, sound only comes from one headphone... and the sound system is re-initialized every time a move is made!". I'm not totally sure how to begin debugging this, though, so I'm filing this report in hopes that the answer is immediately obvious to you, dear reader.

[ornicar]

not immediately obvious to me :)

[niklasf]

Is this happening with all sound sets or a specific one?

[bytbox]

It doesn't happen with all of them. It seems to happen with only standard and robot.

The sound set pentatonic has very long sounds. So, if I switch to that, it starts playing something which takes 10 seconds. While that plays, I switch back to standard. Until the pentatonic thing stops playing, the standard move sounds come from both speakers. Once pentatonic is done playing, standard reverts only to the left speaker. (Playing music in another tab, though, doesn't fix it: the music comes from both speakers, and move sounds come only from the left.)

[niklasf]

Related: https://github.com/ornicar/lila/issues/4983

[isaacl]

I think the standard new game sound is only in left channel

[bytbox]

This seems to be some consequence of the standard sound files being single-channel. When I play the sound Move.js via

var sound = new Howl({src: ['sounds/standard/Move.mp3']});
sound.play();

I hear it only from left channel. Playing sounds/standard/Move.mp3 in an isolated audio player (audacity, or opening directly in my browser) works fine -- I hear from both channels.

Interestingly, if I modify Move.mp3 in audacity by creating a stereo track, with the same audio in each channel, then howler now plays from both the left and the right as desired.

I'm trying to find a better solution than "re-write all audio files to be proper dual-channel stereo".

[bytbox]

This issue only happens when using firefox for me. I've reproduced it directly with WebAudio code. I believe it's an incarnation of https://bugzilla.mozilla.org/show_bug.cgi?id=1435598.

This obviously isn't a bug in anything related to lichess. As of this writing a fix seems to be in the works: https://bugzilla.mozilla.org/show_bug.cgi?id=1567949. So, I don't think a workaround in lichess would be appropriate, and I'm closing this issue.