"De-Emphesis", and/or lack thereof. Affect on sound of CD rips...

[Chr1]

In another thread I was made aware of something that I had never heard of. "De-Emphesis". And how it relates to, and is important, in the retaining of accuracy/sound quality, when playing a rip from a CD.

I would appreciate any input as to how to verify and ensure playback of CD rips is accurate in this respect.

Here's a link to the thread in question...

Can anyone comment on the harsh highs on this XTC recording from 1988?

I signed up for Pandora and one of the things they have correctly identified about me is that i like XTC. This is a brilliant song, wonderful musical performance, etc., but when i heard it immediately after "Sundown" by Gordon Lightfoot, i was shocked at how bright it was. The highs are so...

www.audiosciencereview.com

Thanks in advance.

 

[wwenze]

It will be stated inside the .cue file. Whether the track has preemphesis or not.

 

[Chr1]

Thanks. What if you don't have that though?

I have CD rips from various sources. Some have these, others don't.

I also have thousands of individual Flac track files, from numerous sources as I share with my friends. Mostly from ripped CDs.

How do you know if they are accurate in this case?
Thanks again.

 

[DVDdoug]

Thanks. What if you don't have that though?

Re-rip the CD and make a cue file (with an application that supports cue files (AKA cue sheets). (And an application that can detect pre-emphasis.)

Or, if you don't have rips that sound like the treble is over-boosted don't worry about it!

I found a List of CDs with pre-emphasis. Of course it may not be complete or you might have a different version so you'd have to listen and maybe apply a de-emphasis filter to see if it sounds better or worse.

It's not that common. That's probably why you hadn't heard of it and why most ripping apps don't check for it and apply the correction. And IMO it was a dumb idea.

 

[kchap]

When I was I was converting my CDs to flac using EAC, with the assistance of a few scripts my work flow was as follows:

1. Scan the CD and load into the EAC database.
2. Create a .cue file.
3. Rip the CD, one .wav file per track.
4. Convert to 44.1 k 24 bit.
5. Read the .cue file to determine the pre-emphasis flag setting and apply de-emphasis if required.

In the next stages I would change the sample rate to 192 k and convert to flac. Too high I know but I'm too lazy to change.

Interestingly, I only had a few CDs with pre-emphasis enabled. Since some of my CDs are 40 years old I expected a lot more to have pre-emphasis enabled.

 

[Mart68]

The curve it applies is pretty dramatic, I think it would be obvious if not corrected:

 

[linuxfan]

If a CD is intended to have pre-emphasis, the Red Book standard specifies this be indicated in both the CD's table of contents (TOC) and the subcode (SUBQ). SUBQ apparently requires a more intensive analysis of the TOC, and this can also reveal information about copy protection, which certain legal jurisdictions disallow - thus many/most CD ripping applications deliberately exclude reading of the SUBQ. Normally this would not be a problem ... but unfortunately there are quite a number of commercial CD's from the 1980's which were authored with pre-emphasis without this being indicated in the TOC - so most CD rippers will be unaware of this pre-emphasis.
The rippers I'm aware of which can read SUBQ:
CUERipper - Windows only
Exact Audio Copy, early versions up to 0.95prebeta3 - Windows only
cdda2wav - Linux only

So the online database of CD's with pre-emphasis (which DVDdoug mentioned) is certainly a useful resource.
Another good resource for determining pre-emphasis is a 1980's or early-1990's CD player! These can read SUBQ and should then display something like "EMPH" to let the user know the status.

 

[AnalogSteph]

And IMO it was a dumb idea.

Not so much when it comes to classical recordings (often little going on in the treble regions) in the days of fairly crummy early ADCs. For pop and rock recordings, probably so, yeah.

Using PE seems to have been exceedingly common in Japan up to 1985. You rarely ever see it post 1987 anywhere (unchanged rereleases of older masters may still crop up, occasionally even with the PE flag missing).

If a CD is intended to have pre-emphasis, the Red Book standard specifies this be indicated in both the CD's table of contents (TOC) and the subcode (SUBQ).

Wasn't the kicker that the standard said it should be subcode only?

 

[Scytales]

Former Philips/Sony engineer Black Elk gave some insights on that matter on another forum:

• https://forums.stevehoffman.tv/thre...ode-pre-emphasis.276489/page-16#post-30295942
• https://forums.stevehoffman.tv/thre...ode-pre-emphasis.276489/page-22#post-36155266