Exported MP3 messed up on some platforms, perfectly fine on others

[kozikowski]

It's good to track this back to where the damage is coming from. The two inspection methods are mix to mono and watch the waves mostly vanish, or magnify the waves and see that they are out of step with each other.

If you listen on good headphones you will start to recognize the "sound" of the damage. The sound has a hole in it or sounds like it's coming from behind you. Normal sound is slightly flat and coming mostly from straight ahead.

This is a stereo/phase sound check.

https://www.kozco.com/tech/LRMonoPhase4.mp3

Post back if you find the problem. It's good if we know as many trouble spots as possible.

Also remember this is a forum, users helping each other, not a help desk.

Koz

[kozikowski]

It's not unusual to play that sound clip and discover your stereo sound system is actually mono and the fourth voice vanishes.

Koz

[gumshoe38]

Hmmmm. Now that I've tried both methods, I'm left a little more confused.

Mixing a track down to mono produces a high-pitched version of the track — almost as if it was sped-up.

Inverting the top track produces something entirely different, almost like it is watered down (I've attached a photo of what it looks like uninverted).

Either way, I don't think I've diagnosed my problem. I'm not sure what you mean by "coming from behind me", but it does sound like mini holes in the audio. It sounds static-like, but it's faint. It just becomes very noticeable when I play in something like iTunes or Quicktime.

Anyway, I've listened to my original files in Quicktime to confirm they didn't start damaged, and they sound great! Something about importing these files in audacity are causing these holes.

[kozikowski]

Time to throw a lot more information. What's the show? What are the parts, how are they mixed, who is performing, and on what?

We can only do generic troubleshooting just so long before we're just flapping in the breeze.

I knew the problem had to be phase and Left - Right distortions because that's one of the few problems that can create "magic" shows. It plays here, but it won't play there for no reason we can tell.

Did you play my test sound clip on your devices? "This is my voice on the left...." Did you get any surprises? Are you listening on headphones? The fourth voice , the one intentionally messed up, sounds really creepy on headphones and that can be one of the ways to tell if you're going to have trouble with your own production.

Koz

[gumshoe38]

Sorry for the delayed response, it has been a weekend full of troubleshooting. I have solved my issue, but I still don't know what the exact underlying problem was.

It is simply a radio show! I was mixing mp3 files of songs with voice recordings from a zoom call. The voice recordings are imported as m4a files. There are quite a few tracks -- 10ish, and the final product totals an hour.

The test clip you attached sounded fine on my devices, but sounded a little weird once I imported then exported it via my original .aup file.

I spent a lot of time isolating each audio track, trying to figure out the issue. They each sounded fine when listened to elsewhere, and even when imported into a different .aup file. However, once they were imported into the .aup that I was originally working with, things sounded weird.

So, to solve my issue, I simply copied all my tracks and pasted them into a new .aup. Everything sounds good again! I don't know why the original .aup file was corrupted/messed up. Audacity did crash a few times while I was editing...

[steve]

However, once they were imported into the .aup that I was originally working with, things sounded weird.

So, to solve my issue, I simply copied all my tracks and pasted them into a new .aup

Do you still have that original .AUP file?
If you do, you could attach it to your reply (See: viewtopic.php?f=49&t=64936)

[kozikowski]

Audacity did crash a few times while I was editing...

Do you know what a "doorknob moment" is? A person has been to the doctor's office for a checkup and for the most part passes very well. They're leaving the office and with their hand on the doorknob, turn and say "I throw up blood every night before I go to bed. That's not important, is it?"

Audacity doesn't just crash a few times. I've never had Audacity crash and have only had one instance where Audacity created a damaged recording for no known reason. In years of use. So there is something profoundly wrong to cause that.

I hope Steve has some ideas. This fails one diagnostic trick. If somebody paid me a lot of money to cause this problem intentionally, I'm not sure I could do it. Why would a Project cause phase cancellation problems, only on some sound files, and then give up the good fight and crash multiple times? That's super unusual.

Koz

[kozikowski]

I do note one thing from your illustration. You have a wild mixture of technical standards. The bottom track is Stereo, 48000 we assume from a video. 48000 is a video sampling rate. The top track is Mono 32000. I don't know of a common sound system which uses that. Answering machine? Voice Response System? "Your call is important to us..."

If there's enough tracks in your show, we assume at least one is going to be the common Stereo, 44100. So Audacity will be jumping through hoops to accommodate all those different technical standards in real time.

What's the Project sampling rate, the number in the far lower left?

Screen Shot 2020-09-08 at 3.00.23 AM.png (14.93 KiB) Viewed 202 times

Do you have trouble with some tracks playing at the wrong speed? Are you applying Effect > Change Speed or one of the other Change tools?

Koz