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Pre-emphasis detection in EAC
kikonenko
post Dec 5 2013, 21:42
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Hi, i'm concerned about EAC's pre-emphasis detection reliability. I've made a few rips of my cd collection and some came up pre-emphasized in EAC rightmost column. Also the generated cue sheet has FLAGS PRE. This confirms that EAC has some kind of pre-emphasis detection going. Problem is i read on some other threads that pre-emphasis info may be located in two different places (TOC and subcode) and worse, as one user suggested in a thread, they may contradict each other. As an example: a cdda2wav was posted which found pre-emphasized CD that EAC(1.03) couldn't detect (emphasis logs). A little search shows more cdda2wav log results that back up that claim. Now i'd like to keep using EAC but would hope someone here can explain where exactly EAC looks for pre-emphasis (subcode? TOC? both? why is it missing pre-emp while cdda2wav detects it? the wiki says something about a TOC detection feature that could detect pre-emphasis and copyright in the subcode was discontinued in 0.95 due to European law but that paragraph is rather confusing and i don't really get what it says). I really like EAC but missing pre-emphasis on some of my rips is a huge loss i'm not willing to take.

Thanks in advance for any help smile.gif
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DVDdoug
post Dec 5 2013, 22:13
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QUOTE
I really like EAC but missing pre-emphasis on some of my rips is a huge loss i'm not willing to take.
If there is pre-emphasis, you should hear a difference between the rip and the played CD. If the rip sounds OK, you've got nothing to worry about. wink.gif If the rip is overly bright, you'll need to de-emphasize.

As far as I know EAC doesn't apply de-emphasis, so it's just a warning flag and it's not going to affect the sound in either case.
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pdq
post Dec 5 2013, 22:28
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Are you sure that any of your CDs actually have pre-emphasis? AFAIK there are virtually no discs less than 25 years old that have it.
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greynol
post Dec 5 2013, 22:53
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EAC detects pre-emphasis in TOC only. Whether manual TOC "detection" will find it in the sub-channel data on a per-track basis has been left for user experimentation:
http://www.digital-inn.de/threads/pre-emph...e-in-eac.19034/


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kikonenko
post Dec 5 2013, 22:57
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Hi, yeah it's just that i have a moderately large collection (think few hundreds) and i don't really have the time to listen to them all at the time of ripping. I'm doing this for archival purposes and i'd like my rips to accurately reflect the album's audio contents. Pre emphasis might be noticeable on some albums, but not all. I find joy in analysing more thoroughly the albums i like the most with a good audio analysis app but i wouldn't like this to become an habit for every album i rip. A good ripping program should be able to accurately report what albums have this feature. Actually i don't deemphasize them because that's a lossy process and i want to keep it exactly like it was on cd. Instead i use the F2K de-emphasize addon which does it on the go.

Yeah my albums are quite old wink.gif but pre-emphasis isn't a thing from the past, at least not for some labels who consistently use it in their issues. Besides i read some reissues of old albums have it.

Basically i'd like to know how exactly does EAC (1.03) detect pre-emphasis and why it might be missing the flags for some.

Thanks smile.gif
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kikonenko
post Dec 5 2013, 23:04
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Sorry was typing while you posted. Thanks exactly what i was looking for. I notice the thread you linked is a bit old. I read about 0.95 dropping some TOC reading support.

"Removed features: EAC 0.9 beta 1 (21 Jan 2001) through 0.95 beta 3 (30 Aug 2005) had manual TOC detection as an option, useful if a CD is defective and displays wrong track positions or data tracks instead of audio; EAC will try to detect the CD structure by analysis." This could also be used to detect pre-emphasis and copyright flags in the subcode, since they're sometimes missing from the TOC. The manual TOC detection feature was removed in 0.95 beta 4 (21 Feb 2006) due to European legislation which would outlaw software capable of circumventing a certain type of CD copy protection involving erroneous TOC data."

Do you know if as of 1.03 EAC still reads that TOC data accurately? Thanks a bunch.

This post has been edited by kikonenko: Dec 5 2013, 23:08
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greynol
post Dec 5 2013, 23:11
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Post-0.95b3 reads from TOC only. Determining whether previous versions could read from the sub-channel data on a per-track basis through the feature that was removed in an attempt to comply with laws prohibiting the circumvention of copyright protection is left as an exercise for the user.

If you're paranoid, use cdda2wav. If you're more paranoid use both.

If you wish to improve the knowledge base rather than just leech from it, do both and report your findings.

This post has been edited by greynol: Dec 5 2013, 23:47


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kikonenko
post Dec 6 2013, 00:16
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Thanks, i'll make sure to post regularly with my findings. I'd hope TOC pre-emphasis data matches the subcode data for most cd's, but just to be safe i'll try cdda2wav.

This post has been edited by kikonenko: Dec 6 2013, 00:17
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edwardar
post Dec 6 2013, 10:18
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I use Cueripper, which detects pre-emphasis in the TOC or subcode.

It's frustrating that EAC dropped this feature. I believe it was over issues of copy protection, but I don't see why the pre-emphasis detection function couldn't have been left in.

Anyway, there is an interesting thread on SteveHoffman forums where people list CDs with pre-emphasis:
http://forums.stevehoffman.tv/threads/pre-...16#post-9713720
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greynol
post Dec 6 2013, 13:54
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The link I provided makes it evident that the feature was never intended to detect pre emphasis in what Andre was deeming an incorrectly authored disc (be uses the term illegal). It is readily apparent (to me at least) that Andre doesn't even know if the detection routine would even work.

Regardless, thanks for suggesting another alternative. I found CUERipper to be painfully slow with caching drives, even worse than EAC with the bone-headed monkey-see, monkey-do settings/ripping method.


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Porcus
post Dec 6 2013, 21:00
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Re detection software: dBpoweramp does only detect TOC, just like (recent) EACs.

Re the claim that no-one applies pre-emphasis anymore:
-> For classical music, old recordings are routinely repackaged by some (budget?) label: http://www.hydrogenaudio.org/forums/index....rt=#entry796949
-> Even a few new recordings: http://www.hydrogenaudio.org/forums/index....&pid=793938

Re whether TOC and subchannel agree ... and are correct:
-> The flag need not be correctly set. There could be false positives. And once the pre-emphasis EQ curve is applied, there is no sure guarantee against someone putting it on disc without setting the flag. And it need not be that EQ curve either - a Dolby'ed mastering is blamed for the sound on some early CD version of Skinny Puppy's "Rabies".
-> Another thread here: http://www.hydrogenaudio.org/forums/index....howtopic=100678
-> Here is one release claimed to be flagged only in subcode. http://www.discogs.com/Pink-Floyd-The-Dark.../release/667546
-> In connection to the thread mentioned by the OP, here are three samples of "Money":
http://www.hydrogenaudio.org/forums/index....showtopic=97318


Have a listen at the third - a release I have not stated any identification on - what do you think?


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Lazlo Nibble
post Feb 1 2014, 22:41
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Unfortunately it's not uncommon for discs to have the PRE flag set in the subcodes but not the TOC. My ripping workflow includes a cdrdao pass to check TOC data against the subcodes and so far I've uncovered a half-dozen or more examples in my collection, including titles mastered as late as 1989 (The Blue Nile's Hats) and pressed well into the mid-'90s (my copy of Sandra's The Long Play, which has an IFPI mould SID). If you want to know for sure, you have to check the subcodes.

I maintain a list of discs known to have pre-emphasis here, based largely on information from the Hoffman forums thread. It includes matrix code and TOC-vs.-subcode flag information where I've been able to get it.
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