Pre-emphasis on CDs

[Rolmill]

Many thanks to johnb for the above - I'll certainly be trying out V1 over the weekend.

Just a quick question: am I correct in assuming that V2 (or a similar approach) cannot be used for files already ripped to MP3, because these have been compressed and cannot be restored to wav files?

[johnb]

I wouldn't use the same type of procedure on mp3 files because mp3 is a lossy format and decoding/re-encoding the files would lead to some degrading of the audio quality. Whether the difference would be noticeable is another matter.

[Dave2002]

I wouldn't use the same type of procedure on mp3 files because mp3 is a lossy format and decoding/re-encoding the files would lead to some degrading of the audio quality. Whether the difference would be noticeable is another matter.

I don't know whether it would work satisfactorily with mp3 files. I would suggest giving it a try. There could be HF artefacts which would cause a problem, but on the other hand it might still do the trick. That's working on a .wav or equivalent version generated from the mp3s.

[Phileas]

Although I was aware that some of my ripped CDs might have pre-emphasis, for some reason it's only reading this thread this evening that prompted me to do something about it.

Luckily my collection is relatively small but I checked my BIS CDs and all but two out of eight or nine have PE.

Thanks johnb for the useful script for fixing my existing FLACs.

(I did happen to notice on the first tracks I fixed that the conductor tag "Jarvi" got messed up slightly because my original tag had an umlaut over the a which got converted into something else but it's a minor issue.)

[ChrisBennell]

Interesting discussion which I need to investigate further.

In recent years I have downloaded a lot of CDs and tracks in Flac format from on-line retailers like Presto Classical, as its usually quicker than ordering the CD. I usually burn the Flac files to CD. Does anyone know if these Flac files are also likely to have pre-emphasis? I must admit I have noticed no problems with the sound.

[Dave2002]

I don't know whether it would work satisfactorily with mp3 files. I would suggest giving it a try. There could be HF artefacts which would cause a problem, but on the other hand it might still do the trick. That's working on a .wav or equivalent version generated from the mp3s.

Distracted by the discussions on the bargain thread, and the need to eat, I overlooked the fact that most people with a copy of the CD would not normally need to worry about mp3s, except perhaps for listening on portable players, and many people with legitimate mp3s would perhaps also have the original CDs, so it would be easier to regenerate the mp3 having sorted out the pre-emphasis first. I suppose some people might have downloaded mp3s, and then suspect that the pre-emphasis hadn't been sorted out properly by the suppliers, perhaps based on the kind of information we are building up here, in which case it might be worth trying to adjust the recordings accordingly.

[johnb]

(I did happen to notice on the first tracks I fixed that the conductor tag "Jarvi" got messed up slightly because my original tag had an umlaut over the a which got converted into something else but it's a minor issue.)

Phileas, I think I might be able to amend the script to deal with that problem. I'll get back later today.

[johnb]

Amendment to Version 2 (removing pre-emphasis from flac files while retaining the tag information)

Phileas, can you please try the following amendments and let me know whether they work for you (they seem to solve the problem for me).

There are two changes:

1) The line:
%FLCMETA% --export-tags-to="%FILE%.tags" "%FILE%.flac"
Needs to be changed to:
%FLCMETA% --no-utf8-convert --export-tags-to="%FILE%.tags" "%FILE%.flac"

(The red is the part that is added to the line)



2) The line:
%FLCMETA% --import-tags-from="%FILE%.tags" "%FILE%_16DE.flac"
Needs to be changed to:
%FLCMETA% --no-utf8-convert --import-tags-from="%FILE%.tags" "%FILE%_16DE.flac"

(Again, the red is the part that is added to the line)

For someone who has already set up the batch file described in post #14 the easiest way to make the changes is to right click on the icon on your Desktop, then select "Edit".

Carefully copy and paste the red text into the right place in the relevant lines (making sure there is a space before and after the added text), then save.

I have amended the original in Post #14

[Eine Alpensinfonie]

I am still puzzled as to why pre-emphasis is necessary on a digital medium.

[Stunsworth]

I am still puzzled as to why pre-emphasis is necessary on a digital medium.

It appears (and I could be wrong here) that it was used in early CDs to reduce the amount of noise introduced by using 14 bit chips and 'brick wall' filtering in some early CD players. Essentially as the treble was reduced in volume as part of the de-emphasis process, so were the spuria associated with the players electronics.

[Eine Alpensinfonie]

It sounds like Dolby B.

[Phileas]

Amendment to Version 2 (removing pre-emphasis from flac files while retaining the tag information)

Phileas, can you please try the following amendments and let me know whether they work for you (they seem to solve the problem for me)....

That works. Thanks.

[robk]

Thanks johnb for your help with this.

It works for me too. I had a problem caused by my version of sox being a later one but that was easily resolved once I noticed it.

[Rolmill]

Thanks johnb for your help with this.

It works for me too. I had a problem caused by my version of sox being a later one but that was easily resolved once I noticed it.

Yes, my thanks too - I just used your version 1 script and it worked fine, looks like a great time-saver for me .