Audio output issue

[zackManase]

Using Ui24r connected to Obs for streaming. The audio output channel is 1/2 which throws a good audio output on a streaming link when played through Mac and a few laptops, however for the mobiles YouTube app the audio is squeaky and the signal is dead as well. However few mobile devices the audio output is flowing in. Could this be a reason in OBS or YouTube encoder or Ui24r settings? Please help

 

[AaronD]

Squeaky? Post a recording. Different problems sound different, but everything else you said points to something that wouldn't do that.

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Sounds to me like you've mismatched a common connector for incompatible purposes. Maybe just slapped an adapter on there to make things fit, without realizing WHY they're different???

Anyway, if you adapted a single-plug XLR line out, for example, to a single-plug TRS line-in, then it might sound okay with two speakers, but just one speaker is silent. The reason is:

• XLR is pretty much always mono, or a single signal. Two separate XLR's are required for stereo.
  • Pin 1 = Shield (X)
  • Pin 2 = Live (L), Hot, Positive, Etc.
  • Pin 3 = Return (R), Cold, Negative, Etc.
  • The signal is taken as the *difference* between pins 2 and 3, to cancel the interference that both picked up.
• TRS can be any number of things:
  • Balanced mono, just like XLR:
    • Tip = Hot, Positive, Etc.
    • Ring = Cold, Negative, Etc.
    • Sleeve = Shield
    • The signal is taken as the *difference* between tip and ring, to cancel the interference that both picked up.
  • Unbalanced stereo:
    • Tip = Left hot, positive, etc. (no cold, negative, etc.)
    • Ring = Right hot, positive, etc. (no cold, negative, etc.)
    • Sleeve = Ground (no shield)
    • The two different signals are taken as they are, interference and all.
  • Insert (used on analog mixers, not so much on digital like yours):
    • Tip = Send
    • Ring = Return
    • Sleeve = Ground
    • Two different signals, but different *directions* this time even! It's used to stuff some external processing at some point in the middle of the internal signal chain. A switch in the jack connects tip and ring together when there's no plug in it, so the signal continues on with no processing.

Now, if you just slapped some adapters together to make things fit, you could easily end up with a balanced mono output feeding an unbalanced stereo input. If the balanced hot and cold really are equal and opposite (not a requirement, but one of three common ways to satisfy the actual requirement), then both meters will be exactly equal, and both speakers will seem to do the same thing...except that the right channel is actually backwards: it pulls when the left channel pushes.

That sounds exactly the same...until they combine with each other. Two separate speakers in free air will probably not cancel completely, but electronic mixing almost certainly will. That's probably why most phones are silent. They only have one speaker, and so they mix both channels to send to it. And because you're giving them equal and opposite, instead of equal and identical like you're supposed to, that mixing produces silence.

 

[AaronD]

Now that I think about it, "squeaky" might be compression artifacts that would normally be drowned out by the intended sound, but since the intended sound is completely cancelled as I described above, the artifacts come through.

That would lead to a curiosity question of, "Why does the encoder produce such asymmetrical artifacts in this case?"

One possible answer is that it saves data by encoding a sum and difference signal, instead of two sides, and the sum is higher quality. If that's the case, then the situation that I described above is pretty much the worst possible input that you could give it! The high-quality sum is silent, and the low-quality difference is slammed!