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"Fix" mp3?
eiko
post Mar 20 2009, 05:43
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Is there any app to take an mp3, or a WAV that was previously compressed to mp3, and add high frequency sounds in plausible locations that mp3 encoding would have removed?

Thanks

This post has been edited by eiko: Mar 20 2009, 05:43
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timcupery
post Mar 20 2009, 06:07
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Before we talk about applications to do what you want, let's figure out what you're looking for first - what you want to accomplish, and whether anything can do it, and what comes closest.
I assume you're talking about dithering. This basically adds noise to an audio stream, and as such fills in higher frequencies that may have been lowpassed out through encoding. However, this won't fill in the frequencies that were lost upon lowpassing.

If your goal is to take lossy material and make it sound less lossy, you're mostly out of luck.

But I may be misreading your intent. What are you hoping to accomplish?


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[JAZ]
post Mar 21 2009, 20:06
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QUOTE (timcupery @ Mar 20 2009, 06:07) *
I assume you're talking about dithering. This basically adds noise to an audio stream, and as such fills in higher frequencies that may have been lowpassed out through encoding.



Were you serious?
First, i believe you wanted to say noise-shaping when you said dither, but even then, if that noise was of a comparable level of a content in those frequencies, it would be destroying more than helping. (Also, noise shaping increases with the frequency, and audio usually decreases with the frequency)


For the OP. You have another experiment, if you want: record the output of an (Creative) X-FI Soundcard with the "mp3 enhancer" enabled. The only problem is that it may change the audio too much.
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timcupery
post Mar 22 2009, 20:28
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QUOTE (eiko @ Mar 20 2009, 23:38) *
Yep. It's for a noble cause. ;)

It seems like none of us believe you that it's for a noble cause. Might you be willing to explain why it's something other than the three possible explanations that have been mentioned? If it is a different reason than one of those three?

QUOTE (ameyer17 @ Mar 21 2009, 11:48) *
EDIT: This moderation is getting to be a bit ridiculous. I'm leaving.

Get over it. A nice thing about HA is that people aren't full-quoting the post directly prior to theirs all the time, and this makes threads easier to read. Nobody hurt you.
Quoting is useful where you're replying to posts that aren't directly prior, or replying to a number of different things in a given post.

QUOTE ([JAZ] @ Mar 21 2009, 15:06) *

QUOTE (timcupery @ Mar 20 2009, 06:07) *
I assume you're talking about dithering. This basically adds noise to an audio stream, and as such fills in higher frequencies that may have been lowpassed out through encoding.

Were you serious?
First, i believe you wanted to say noise-shaping when you said dither, but even then, if that noise was of a comparable level of a content in those frequencies, it would be destroying more than helping. (Also, noise shaping increases with the frequency, and audio usually decreases with the frequency)

I was serious. Although I might have meant noise-shaped dither. I don't know all of the differences here. To my knowledge, dithering adds high-frequency noise and makes lowpassed audio streams appear (to a spectral analyzer) as if they weren't lowpassed.

This post has been edited by timcupery: Mar 22 2009, 20:29


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