Shoutbox

lo,

Wanna ask if someone knows a quality program that can compare MP3's.

What I want to do is to compare only the decoded audio stream. So differences in the ID-tags (how exothic they might be) must be ignored.

It would be perfect if the program also can produce the differences in a graphical way (specograph), so I can see where exactly the differences are...

On the same subject, I'm also seeking a program that can edit all ID-tags and read other parameters/info (like encoding, (variable) bitrates, etc...) within an MP3.

Also... does someone have the specs of the MP3-file format? (I can google this, but more sources means, I have more certainty that the specs are correct and complete)

quote:

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Originally posted by CookieRevised
On the same subject, I'm also seeking a program that can edit all ID-tags and read other parameters/info (like encoding, (variable) bitrates, etc...) within an MP3.

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what about Sound Forge?

quote:

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Originally posted by CookieRevised
Also... does someone have the specs of the MP3-file format?

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are they public? don't you have to pay for them? or was it when you wanted to do a program that encodes in mp3?

quote:

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Originally posted by CookieRevised
What I want to do is to compare only the decoded audio stream.

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that's quite difficult, because 2 decoded auido strams may be diferent and you'll hear the same. what you're looking for should do a frequency analisys and show results... quite complex software...

If what you want to compare are 2 wav (for example) files compressed in mp3 with diferent parameters (bitrate, quality, ....) maybe you can do this:
Open the files (MP3s) in soundforge and "substract" the files. You can do this inverting one file, copying it and pasting (with mixing) on the other. now listen to the result and hear the diferences yourself. (soundforge can show specographs, i think).

This way is a bit dodgy but maybe you get what you want. I'm not sure, I never did that.

quote:

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Originally posted by Choli

quote:

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Originally posted by CookieRevised
On the same subject, I'm also seeking a program that can edit all ID-tags and read other parameters/info (like encoding, (variable) bitrates, etc...) within an MP3.

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what about Sound Forge?

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Didn't think of that... thanks... I'll try...

quote:

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Originally posted by Choli

quote:

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Originally posted by CookieRevised
Also... does someone have the specs of the MP3-file format?

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are they public? don't you have to pay for them? or was it when you wanted to do a program that encodes in mp3?

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I'm not looking for the MPEG-3 encoding itself, but the fileformat of the MP3. I dunno if the MPEG-3 encoding is public or not, but the MP3 fileformat must certainly be documented very clearly somewhere... (an analogy to the GIF-fileformat as example of what I mean: I'm looking for the physical buildup of the fileformat, but not the LZW-compression which can be used by GIF)

quote:

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Originally posted by Choli

quote:

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Originally posted by CookieRevised
What I want to do is to compare only the decoded audio stream.

---

that's quite difficult, because 2 decoded auido strams may be diferent and you'll hear the same. what you're looking for should do a frequency analisys and show results... quite complex software...

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yeah... and that's exactly what I want

quote:

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Originally posted by Choli
If what you want to compare are 2 wav (for example) files compressed in mp3 with diferent parameters (bitrate, quality, ....) maybe you can do this:
Open the files (MP3s) in soundforge and "substract" the files. You can do this inverting one file, copying it and pasting (with mixing) on the other. now listen to the result and hear the diferences yourself. (soundforge can show specographs, i think).

This way is a bit dodgy but maybe you get what you want. I'm not sure, I never did that.

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Not useable for what I want right now, but I'll keep this "trick" in mind... thanks...

It's time to be picky again!

quote:

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Originally posted by CookieRevised
I'm not looking for the MPEG-3 encoding itself, but the fileformat of the MP3. I dunno if the MPEG-3 encoding is public or not, but the MP3 fileformat must certainly be documented very clearly somewhere... (an analogy to the GIF-fileformat as example of what I mean: I'm looking for the physical buildup of the fileformat, but not the LZW-compression which can be used by GIF)

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MP3 is based on MPEG Audio Layer 3 encoding - that is, MPEG1, not to be mixed with later revisions of the MPEG standard. As far as I know, MPEG3 was aborted and never used in the big world... So there's just MPEG, MPEG2 (used in DVDs) and MPEG4. MP3 is a part of the original MPEG specification.

As to your question, I really have no idea. MP3 is a proprietary format that belongs to the German Fraunhofer IIS. It's not an open format like Ogg. I don't think if you're even allowed to encode audio without a license... So I guess you'll have to google it hard.

hehehe...

Anyways, I don't need the (licensed) encoding/decoding itself (avoiding the name mpeg/mp3/whatever here otherwise I'll make a mistake again ) I needed the fileformat: where are the tags stored, what are the first bytes indicating, etc... etc...
=> found plenty of info on sites like http://www.wotsit.org/, http://www.filespecs.com/, ...

On the other part, I needed a program that could compare the uncompressed audio streams of two mp3-files easly (without converting the mp3 first to a PCM, then comparing those PCM's, etc... etc...) (<= dont say I use the term wrong again )
=> still didn't try out SoundForge, so I dunno...

EDIT: by this time I've indeed found plenty of info about the MPEG audio format and everything I need (including the official licensed papers)...