pre-emphasis and archiving and cdda2wav

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krabapple
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Postby krabapple » Tue Apr 11, 2006 10:19 am

MK wrote:I don't see any PE flags on the CD-R.

I ripped the Toshiba CD with iTunes and burned with iTunes. I was under the impression doing this in iTunes would create a correct sounding copy with no PE flags. Or did I miss something?


No, this is what is supposed to happen...assuming there are PE flags set on the CD in the first place. Now, I wondered a week or two ago here how itunes would treat discs with 'cryptic' PE...that is, pre-emphasized discs that aren't recognized as such by software that detects PE flags (e.g. EAC).

Do this - copy your original using EAC, but before burning look at the CUE sheet and make sure the PE flag is set for each track. If it isn't, set it. That should sound normal in your CD player. *Then* try playing that in iTunes. If it really does what people say it does, your CD should sound normal when ripped.


Which is what I suggested back on Mar 31 here

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Postby lukpac » Tue Apr 11, 2006 10:23 am

krabapple wrote:No, this is what is supposed to happen...assuming there are PE flags set on the CD in the first place.


But not only are the PE flags not there, iTunes didn't adjust the audio either. As is my understanding, anyway.
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Postby krabapple » Tue Apr 11, 2006 11:45 am

lukpac wrote:
krabapple wrote:No, this is what is supposed to happen...assuming there are PE flags set on the CD in the first place.


But not only are the PE flags not there, iTunes didn't adjust the audio either. As is my understanding, anyway.


The initial report was the itunes correctly rips CDs where the PE flag is on. That is, it applies de-emphasis on the fly and thus the resulting wav is PE-compensated (de-emphasized)...it will sound correct with software players, for example. If re-burned to disc it will no longer show a PE flag, nor will a CD player apply de-emphasis, but *will* have the correct sound because it was already de-emphasized. My question initially was whether itunes could de-emphasized a rip on the fly from a disc which was in fact pre-emphasized, but whose PE flagging was faulty (which IIRC describes the Japanese Abbey Road). I would not expect itunes to be able to do this, as I would expect it would need a valid PE flag to key off of. The way around this is to do as you and I have suggested -- rip with EAC, then reburn with EAC with manually-set PE flags in a CUE sheet, then rip again with itunes.
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Postby lukpac » Tue Apr 11, 2006 11:47 am

krabapple wrote:My question initially was whether itunes could de-emphasized a rip on the fly, from a disc which was in fact pre-emphasized, but whose PE flagging was faulty (which IIRC describes the Japanese Abbey Road). I would not expect itunes to be able to do this, as I would expect it would need a valid PE flag to key off of. The way around this is to do as you and I have suggested -- rip with EAC, then reburn with EAC with manually-set PE flags in a CUE sheet, then rip again with itunes.


I wish we could tell exactly what the deal is with the PE flags on that disc - audio players don't seem to have any problems reading them.
"I know because it is impossible for a tape to hold the compression levels of these treble boosted MFSL's like Something/Anything. The metal particulate on the tape would shatter and all you'd hear is distortion if even that." - VD

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Postby krabapple » Tue Apr 11, 2006 11:52 am

And IIRC at least one persion here claims to have ripped it successfully (de-emphasized) with itunes...so 'is a puzzlement'. Maybe as has been suggested, some software versions (e.g. of Quicktime) are better at detecting the subcode than others. And maybe hardware does it a different (and more thorough) way.

It should be easy to test the various suggestions here-- but not by me, since I don't have the disc.
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Postby MK » Tue Apr 11, 2006 12:27 pm

lukpac wrote:But not only are the PE flags not there, iTunes didn't adjust the audio either. As is my understanding, anyway.


Correct.

edit: never mind, found it
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Postby Crummy Old Label Avatar » Tue Apr 11, 2006 6:08 pm

What are some "common" discs with pre-emphasis? Don't know why I care, but if it turns out I actually own a disc with PE, I'd like to see if iTunes de-emphasizes it.

Is EAC the only ripping software that recognizes PE? I don't even know if any of the usual Mac/*nix rippers even check for the pre-emphasis flag. I do know that cdda2wav will deal with it if you manually input the correct instruction in the commandline, but I guess that means you'd have to know that the PE is there to begin with. What about Toast? (I do know thast Jam allows you to *set* the pre-emphasis bit, if you so desire, but that's CD creation, not ripping). I don't believe that xACT and/or Max detect PE, but I could be wrong.
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Postby Ess Ay Cee Dee » Tue Apr 11, 2006 6:54 pm

I don't think there's really such a thing as "common" CD's with pre-emphasis. It seems to exist only on very early releases, most of which have been rendered obsolete (and rather rare) by subsequent remasters.

The only one I've ever found in my collection was an old Archie Shepp CD on Denon. I only noticed because I ripped a backup copy with EAC before I sold the original on eBay.

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Postby Xenu » Tue Apr 11, 2006 7:52 pm

I had some sort of "Best of Computer Music" disc (quick explanation: this was during my "check out the entire jazz/classical portion of the U of C library and rip to FLAC" stage, in its "OK, gotta cover the avant garde base" substage) that said it had preemphasis...it was from 1993 or something, though, and I thought that very dubious.
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Postby krabapple » Wed Apr 12, 2006 9:56 am

Crummy Old Label Avatar wrote:What are some "common" discs with pre-emphasis? Don't know why I care, but if it turns out I actually own a disc with PE, I'd like to see if iTunes de-emphasizes it.


The only ones I recall noticing offhand when I was archiving my discs, were a couple of classical music releases. This one:

http://www.amazon.co.uk/exec/obidos/ASI ... 23-2474839

and this one:

http://www.amazon.com/gp/product/B00000 ... nce&n=5174

neither of which I would call common :lol:
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Postby Crummy Old Label Avatar » Wed Apr 12, 2006 5:06 pm

I've yet to read a convincing explanation of why the hell pre-emphasis was ever built into the CD spec anyway. Honestly, what the hell is the purpose of it? Why did the engineers feel this was needed? There must have been a compelling reason, but I cannot for the life of me imagine what it could be.
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Postby lukpac » Wed Apr 12, 2006 5:12 pm

"I know because it is impossible for a tape to hold the compression levels of these treble boosted MFSL's like Something/Anything. The metal particulate on the tape would shatter and all you'd hear is distortion if even that." - VD