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Comment by Sakos

5 months ago

What's the audio left/right balance bug?

To quote Apple's own (no longer available) KB-article from 2012 [1]:

"In some cases the audio balance may unexpectedly drift towards the left or right channel. This can happen if you rapidly press the volume up or down keys while the computer's microprocessor is under heavy load."

[1] https://web.archive.org/web/20120630125615/https://support.a...

  • Wow, I can't even start to imagine how this bug came into existence (and why it should take so long to fix it)...

The audio balance on Apple computers changes randomly, and has done so for at least a decade.

https://apple.stackexchange.com/questions/79384/audio-balanc...

  • Yep, I’ve very much discovered and confirmed this behaviour independently, I was so shocked to learn that it was a known issue.

    I know it’s silly but it helped me with imposter syndrome to see such a major OS that prides itself on seamless “it just works” experiences tolerate bugs like this.

    That and the fact if you airplay a movie to Apple TV it thinks you want it to cast over the top of it with random advert videos in your web browser, so you can’t watch and browse.

    We’re all human I guess ;)

    • But a lot of those bugs are basic functionalities, it is just that they are not the path Apple wants you to take.

      For years now, and across iphone models and iOS versions, my iphone randomizes the artwork of the mp3s in the music app (ie display the wrong album cover). I see people complaining about that in forums but I guess if you are not using Apple Music they don't care.

      I don't seem to be able to copy files from my iphone onto a windows desktop. Tried several cables, the transfer fails after a few GB. I guess if you are not syncing your files through iCloud they don't care.

      A bug recently corrupted the iphone mail app. It wouldn't sync mails anymore, in fact would display old mails from the wrong account (I have multiple setup). I only fixed it by deleting the accounts and recreating them. That's using ActiveSync. But I guess if you don't use an apple email they don't care.

      Another bug on my ipad. The USB-C DAC often fails to be recognised. Tried several DAC. I thought it was a hardware problem (usb port damaged), except that few hardware problems are resolved by rebooting. But if you don't use apple wireless headphones they don't care.

      These are basic functionalities, but not using the main path which happens to be the most profitable to Apple. Apple's reputation for quality is inconsistent with my experience of their products.

      2 replies →

  • Following the link, and a few more, describes at as changing "when volume buttons are pressed during high CPU load". That is perhaps random-seeming, but also way different from actually being reandom.

    I have never used a (modern) Mac long enough to listen to audio, so I have no experience with this I just thought it sounded odd.

    Now having learned that, I really (really) wonder how such a bug can happen, and how it can stay ignored for so long by the always-ranted-about masters of vertically integrated luxury computers. More the former, though.

    It sounds almost as if there already is software somewhere that is doing something to maintain the proper balance (perhaps due to bugs in the hardware), and then that something becomes CPU-starved and/or interrupted when the volume changes, and doesn't resume properly. This is a wild guess straight outta ... Hampton, I have no clue about Mac hardware or macOS internals. Fun to think about, though!

    I hope they fix it for real, soon!

    • > Now having learned that, I really (really) wonder how such a bug can happen, and how it can stay ignored for so long by the always-ranted-about masters of vertically integrated luxury computers. More the former, though.

      My first guess was that "volume up" is actually "increase volume on left channel" and "increase volume on right channel"

      And when there's high CPU load, one of those commands gets lost or ignored for some reason.

      3 replies →

    • There are worse bugs that happen under high CPU load - I reported that you can interact with applications behind the hibernate Lock Screen… 9 years ago. You still can.

  • I've been using macs since the 90s for "serious amateur" music production, and I listen to music while working on an MBP daily, both via the headphone jack and via a USB audio interface, and I've never encountered that. Is there no idea what triggers it?

  • FWIW, I just ran the following stress test for a bit in VSCode, and then mashed the Vol +/- buttons on an M1, and noticed that the volume toggle started to lag, but I didn't notice any balance drift. Is this something that would be reflected in the slider, or is it auditory-only?

    +function() { while (1) { for (var i = 0; i < 1000000000000000; i++) { console.log(i); for (var j = 0; j < 1000000000000000; j++) { console.log(j); } } console.log('herewegoagain'); } }();

    • In my experience the slider definitely moves. You can see it in real time with the settings page open

  • I use my Macs for audio a lot, including with headphones, and have never experienced this in 20 years.

    • This is one of those things that make you question reality somewhat as I know, from seeing countless videos and having some familiarity with the topic, that macs dominate desktop music production - I've never seen a producer or a DJ using windows, ever. This is apparently because the USB audio stack on mac is so streamlined that the buffering is minimal, i.e. you can basically apply realtime audio effects and mix 'live' using a USB output sink, i.e. that you can DJ with it.

      Now apparently there's a game-breaking bug? For 10 years? And it's a really really big deal?

      Hmm.

      1 reply →