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Topic: Subcode pre-emphasis on CDs (Read 3364 times) previous topic - next topic
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Subcode pre-emphasis on CDs

The excellent wiki has this to say about pre-emphasis on CDs.

Quote
A pre-emphasis flag for each track is normally stored in the subcode along with the audio data. It's also supposed to be stored in the table of contents (TOC), but many CDs have TOCs that say there's no pre-emphasis when in fact the subcode says there is. There are also some CDs which people believe were mastered with pre-emphasis, but which have no pre-emphasis flags set at all.

My understanding is that a CD player will still apply pre-emphasis to a CD that has subcode pre-emphasis flags, but doesn't have TOC pre-emphasis flags.

Is there any software which can detect subcode pre-emphasis flags?  I know EAC only detects it if it's in the TOC.   I've been doing some Googling and I find different posts about dBPowerAmp.  So posts say it will do it.  Others say it will not.

And before you ask, yes I have old CDs pressed in Japan for US sales that I want to make sure I rip properly.

Re: Subcode pre-emphasis on CDs

Reply #1 –
You will probably only want to tag that they have pre-emphasis, since there are players, foobar2000 included, which can detect file tags indicating this, and conditionally apply a (third party) DSP filter at play time.

I only suggest this method, since the processing is not lossless. It does not have psychoacoustic compression type behavior, but it does have potentially irreversible spectrum alteration on the audio signal, due to the nature of such processing.

Re: Subcode pre-emphasis on CDs

Reply #2 –
The processing itself could be (almost?) reversible, but to store the result you need to choose a precision; if it's rounded to just 16 bits, this won't be reversible. If it was stored with sufficient precision, it's possible that an inverse filtering and subsequent rounding would give exact original, but it'll require way too much space to store and you'll need a way to exactly describe the filtering to undo. With the exact description of filtering, it's just easier to filter at playback time.
a fan of AutoEq + Meier Crossfeed

Re: Subcode pre-emphasis on CDs

Reply #3 –
Quote from: kode54 on
You will probably only want to tag that they have pre-emphasis, since there are players, foobar2000 included, which can detect file tags indicating this, and conditionally apply a (third party) DSP filter at play time.

I only suggest this method, since the processing is not lossless. It does not have psychoacoustic compression type behavior, but it does have potentially irreversible spectrum alteration on the audio signal, due to the nature of such processing.

Well, the idea here is to rip the CD to CUE/FLAC for backup.  If the CD does have pre-emphasis, but only in the subcode, I could manually add the PRE tags to the CUE sheet.

I did this once before with Genesis - Genesis, an album known to have pre-emphasis that is NOT tagged in the TOC OR the subcode.

I'm using streaming software for the most part, and just want to remove the pre-emphasis.  I always have the CD as a backup, so if I apply a permanent filter that irreversibly alters the file, I'm not going to sweat it.  The goal is to go from CD->FLAC->De-emphasized FLAC->AAC.

Just need to know how to detect subcode only pre-emphasis.

Re: Subcode pre-emphasis on CDs

Reply #4 –
Quote from: magicgoose on
The processing itself could be (almost?) reversible, but to store the result you need to choose a precision; if it's rounded to just 16 bits, this won't be reversible. If it was stored with sufficient precision, it's possible that an inverse filtering and subsequent rounding would give exact original, but it'll require way too much space to store and you'll need a way to exactly describe the filtering to undo. With the exact description of filtering, it's just easier to filter at playback time.

I'm not horribly worried about whether the process is reversible.  I always have the CD to fall back on.  I just want to be able to know if an older CD I have has subcode pre-emphasis.  Then I can put a dot on the jewel case with a permanent marker or something to mark it in case I ever have to rerip.
 

Re: Subcode pre-emphasis on CDs

Reply #6 –
Quote from: shaboo on
Quote from: apastuszak on
Is there any software which can detect subcode pre-emphasis flags?
CUERipper does. XLD (for Mac) also does.

https://wiki.hydrogenaud.io/index.php?title=Comparison_of_CD_rippers

Ok, I need to read up on XLD to see how this works.  I didn’t see it in the options anywhere.  I guess I should check the cue sheet it generates.

Re: Subcode pre-emphasis on CDs

Reply #7 –
This is another one that uses the Q subchannel control bits to get the FLAGS PRE.  As a large picture because that's what I seem to always do.  It's a simple ripper, from the outside.  There's a Where's Waldo in there, but don't look for it too long.





and just to be sure, I ripped a CD that I know has this.  Notice the FLAGS PRE in the .cue.  You can see the lit-up PRE lamp near the times.




BANNED

Re: Subcode pre-emphasis on CDs

Reply #8 –
Quote from: 40th.com on
This is another one that uses the Q subchannel control bits to get the FLAGS PRE.  As a large picture because that's what I seem to always do.  It's a simple ripper, from the outside.  There's a Where's Waldo in there, but don't look for it too long.





and just to be sure, I ripped a CD that I know has this.  Notice the FLAGS PRE in the .cue.  You can see the lit-up PRE lamp near the times.






What app is that?

Re: Subcode pre-emphasis on CDs

Reply #9 –
Jukebox 2112
BANNED