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Pre-emphasized files playback on Mac

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I know iTunes can playback pre-emphasis CDs on the fly applying the required filtering to de-emphasize them, but it won't play FLAC files, nor will apply the de-emphasis filter on ALAC files made from pre-emphasized FLAC files. So it's either de-emphasizing the FLAC files using SoX or some other filtering tool and playing back the new corrected files on your preferred software, or using some software that can de-emphasize FLAC files on the fly. Does this even exist? I'd like to know about any music playback software for OSX that can play pre-emphasized lossless files applying the required filtering on the fly. Thanks.

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I never knew about this. But after reading your post, I did a little digging and (so far) I'm finding what you said about using SOX to de-emphasize and then convert from FLAC.

Sorry to just parrot what you said in your post but I'm interested to see if there are other solutions.

BTW, do you have very many FLAC files like this and where did they come from?

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Pre emphasis correction in dac hardware is trivial. The CS8412 receiver, for instance, has a pin that goes low when it detects pre emphasis, and the PCM1794 DAC requires setting one pin high for pre emphasis conversion. So it is usually just connecting one pin to another, or as above doing so via an inverter or something. That said, I have never seen a pre emphasis track in my life, so I have never even bothered to do that much. But most commercial gear probably still will.

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I guess the standard is IEC 60908.

It's actually pretty significant down 9.49 dB @ 20khz.

I have a couple of eq plug-ins that have presets for pre and de emphasis (Ozone 5 by iZotope and Pro Q2 from FabFilter).

Here's a discussion of the curve on the Audacity forum;


Using a plug-in with a DAW would be way more work than using something like SOX I'm guessing.

Edited by ironbut
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Yes, on Windows you have Foobar 2k which uses a plug-in. This plug-in is activated when Foobar detects the pre-emphasis flag on the TOC if playing a CD, or if the flag is present in the cue file (this is read by any proficient ripping software). What I'd like to know/use is some software on Mac doing the same.

I have found over the years quite a few releases from the early to mid eighties that are pre-emphasized, many happen to be collectable japanese editions of classic jazz albums, even classical music. I don't own many, but they can be found from digital music sources already ripped. PM me were you interested. When getting one of this lossless pre-emphasized files you can do one of three: toasting a CD using the cue file, so the CD is an exact copy and would play on any player or transport/DAC with the pre-emphasis filtered. This could be detected by iTunes too. The second option is doing a lossless into lossless conversion but using some of the filters available, like those by iZotope, SoX, etc, there's even a program for Windows which directly converts and de-emphasizes, so the copy is playable on any computer and software combination. The third option, the one I'm investigating so I don't need keeping more than one copy of the files, is using some software that can either detect the pre-emph flag on the cue file, or just applying the filtering if you tell it to do so. This is what Foobar does by means of a plug-in.

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An update in case someone is interested. Audacity would apply a preformed EQ curve to correct the pre-emphasis, it's described in the thread ironbut mentioned. Some of the things aren't the same in the current Audacity version, but creating the xml file with the curve and asking Audacity to use it is rather simple and similar. Audacity performs the equalization first over the file, then you can play it but it won't be altered if you don't save changes (I'm hoping).

It's interesting looking at the spectral analysis plot, the change is rather noticeable after the de-emphasis is applied. Still open to try other alternatives. I've tried to do it on SoX using just the play and deemph commands, but it's not working, it always complains about the filename or some other shit. I really suck at Terminal console syntaxis, I have no idea why it's not working. I not even was able to get SoX converting the file into a de-emphasized one :palm:

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I meant to respond to your post but quickly forgot.

Regarding Audacity,..

Most audio editing programs these days are non-destructive, meaning you need to force the program to "overwrite" the original file. 

It is easy to create another file that has any processing "baked in" so you aren't forced to open the software (Audacity in this case) to listen to the corrected file. 

Once you have the processing (eq in this case) the way that you want it, you can "render" or "bounce" or whatever your particular software calls it. 

I'm not sure if I'd be that critical about the precision of the eq de-emphasis curve since most digital eq's these days are far better than the ones that were used during pre-emphasis. 

When I say better, I should probably say different and without knowing exactly the processing that was used and how it was applied, you'd be hard pressed to get close to a clone of the original file.

I'd say that "if it sounds good, it is good" should be your final guide.

Anything past that is a job for the archivists.

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