Old 05-23-2014, 05:31 PM   #1
ChetStrzepa
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Default Lossy compression artifacts

Probably a dumb question, but anyway....is there any way to remove or turn down the artifacts of lossy compression? I'm working on "psuedo remastering" of a complete mix, but the audio is only available in lossy format. That "wooshy" or flanging sound from the lossy compression can be heard somewhat, and I wonder if there's any hope of removal or reduction.

Thanks
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Old 05-23-2014, 08:39 PM   #2
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Looks like Zynaptiq still hasn't released Unchirp which was slated for mid 2013 release. Their products are pretty interesting (I demo'd Unveil which removes reverb and I will certainly buy it the next time I need to do that). It could be an any day now situation, not sure about that.

I've really never had much luck with removing compression artifacts personally. For me it's either live with it (for a sound effect on a television mix I can often live with it but I'm not sure I could live with a full mix that way) or find an alternate copy or replacement.
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Old 05-24-2014, 12:47 AM   #3
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It's not really possible to remove any of that without making the track sound odd.

Obviously it would be better to get a mix that isn't pushing the sound towards these artefacts but i'm guessing that this isn't possible or you'd do that!

You could try removing the most obvious noises with Spectro or Izotope RX and then put back some top end (if it's top end where the problems are) with some harmonic distortion.
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Old 05-24-2014, 07:34 AM   #4
ChetStrzepa
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Thanks, very good tips.

I'm thinking of maybe trying some mid-side processing as well.

The main issue I hear is that sort of whooshing sound. Almost like a flanger operating in the upper freq range.
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Old 05-24-2014, 09:03 AM   #5
serr
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Quote:
Originally Posted by ChetStrzepa View Post
Probably a dumb question, but anyway....is there any way to remove or turn down the artifacts of lossy compression? I'm working on "psuedo remastering" of a complete mix, but the audio is only available in lossy format. That "wooshy" or flanging sound from the lossy compression can be heard somewhat, and I wonder if there's any hope of removal or reduction.

Thanks
Short answer is no. Just do the best you can. Spend the extra effort trying to track down the unmolested recording if at all possible.

I've had magical results using iZotopes RX2 spectral repair tool to remove artifacts/sounds from a recording before. You may find this useful but in your case the artifact is the remains of what was originally content (eg. that weird buzzing sound used to be a cymbal). You might find removing a sound leaves an empty hole as it were.

Just do the best you can with what you have left. (Don't feel too bad. Would you believe this exact thing happened to the original moon landing video?)
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Old 05-24-2014, 10:26 PM   #6
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I think they found a better copy from a South African relay station...


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Old 05-25-2014, 07:07 AM   #7
ChetStrzepa
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I received the tracks on an audio Cd, so I was really disappointed to find they were burned from a lossy format. It turns out I had two files; both lossy but one was clearly better, so I switched to the better one.

The artifacts were present in both the mid and sides, but as I read recently in another thread, they were much more prominent in the side track and low pass filtering did help. I kept my other processing on the mid channel, which helped, but I also had to sacrifice some high end on the mid track.

It turned out to be a compromise between the artifacts and the degree of butchering of the cymbals basically.
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