Squeaking/Chirping sound on some mp3 versions of mastered tracks

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Level 1

9 points

Squeaking/Chirping sound on some mp3 versions of mastered tracks

Hello, I've released a number of tracks & remixes on a few different labels, and for the most part, my experiences were good. But I have encountered a new problem that is pretty distressing. I have two tracks on an upcoming compilation album, and the label's promo mp3 versions have a squeaky/chirping sound that occurs for the first 19 seconds of both of my tracks (and doesn't reappear after the 20 second mark). The sound is pretty much in rhythm with the kick. The label's mp3 promos are 320 kbps/44.1k/Joint Stereo. This sound doesn't appear on the other tracks in the compilation.

The sound doesn't occur on my masters, which are a 16 bit/44.1k .wav files. And when I convert the masters to mp3s myself (using the same settings as the label), the squeak/chirp is not present. In fact, after I reported the problem to the label, the label asked me to send them my own mp3s, and they replaced their mp3s with my mp3s on their promo server. But after they uploaded my versions to their promo service, the chirping sound somehow got on the tracks again. Before the label uploaded each time, they added metadata (title/artist/album/genre/year/track number) and added artwork.

Does this problem sound familiar to anyone? Or can anyone suggest a method for troubleshooting? Thanks for anyone's help.

Logic Pro X, OS X Mavericks (10.9.5), Logic Pro X v 10.1.1

Posted on Apr 21, 2015 9:12 AM

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Answer 1

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Pancenter

Level 6

14,632 points

Apr 22, 2015 1:21 PM in response to trobert225

Usually that type of sound is related to:

1. Compressing an mp3 file a second time.

2. A lower rate of compression.

3. Compression of a sound that is over 0db. (all kinds of strange stuff happens if your audio is over 0db or, so much of a certain frequency is present that the mp3 compression algorithm can't handle the frequency saturation.

When they add the metadata is the file then recompressed or is the gain structure changed? (sounds to me like it's recompressed)

What do they use to add the Metadata?

How loud is that bass drum?

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Answer 2

Pancenter

Level 6

14,632 points

Apr 22, 2015 1:34 PM in response to trobert225

Out of curiosity... which was it?

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Answer 3

trobert225 Author

Level 1

9 points

Apr 22, 2015 1:56 PM in response to Pancenter

Hey Pancenter, sorry, I hit "solved" by accident, and I thought I replied too, but apparently I got distracted and forgot to hit the reply button 😝

I actually don't know the answer yet, but I suspect that the label's promo service is re-compresing the files after they are uploaded. I did check the level of my masters with Logic's Level Meter (with ISP option enabled), and one of my tracks does hit +0.2 a lot (my mistake in mastering, and a lesson learned), but my other track never goes above -0.2, and both tracks have the exact same distortion, for only the first 19 seconds of each track.

The label is inquiring with the promo service as to whether they are re-compressing the files for streaming, and they said they'd let me know what they find out. So if I find out something I'll definitely post it here.

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Answer 4

Pancenter

Level 6

14,632 points

Apr 22, 2015 3:25 PM in response to trobert225

Depending on how they're adding metadata, recompression can happen there as well.

Check these when Bouncing to mp3:

1. Do Not use Variable rate encoding, make sure that box is not checked.

2. Use Best Encoding - enabled

3. Filter Frequencies Below 10hz - I also have enabled

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Answer 5

trobert225 Author

Level 1

9 points

Apr 23, 2015 6:19 AM in response to Pancenter

I use all the same settings that you mentioned for MP3s that I make. One question, typically I make my MP3s normal stereo, because I don't see any advantage in using joint stereo. But the label (or their promo service) made the promo copies joint stereo. I wonder if that might possibly contribute to the problem?

I did ask the label what software they use to add the metadata, but they didn't tell me, maybe because in the same email I asked them about their promo service, and when they answered they focused on the promo service. It's pretty frustrating, but I'm still working on it, and I'll keep you posted. Thanks again, I really appreciate your help.

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