Thanks for the tip on CUERipper. I’ve been relying on TOC only since EAC removed subcode detection.
Thanks @WiWavelength for raising this issue. I had missed it earlier this year but it may well explain some of the dissatisfaction users have experienced with the mixing of particular albums over the years.
Let’s flag @brian and ask him whether Roon has any plans as to identification and de-emphasis or whether this is now a historical anomaly that is better left to users.
Without the transfer function of the pre-emphasis filter an IIR de-emphasis filter is going to be a guess. Would applying a -6 dB shelf cut from 10k up in the PEQ be a reasonable approximation ?
No objection to supporting a tag and using it to trigger a DSP correction. The redbook de-emphasis filter is well known. We should do the same for content with inverted phase.
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Several months ago, I offered to write up a Roon user primer on pre-emphasis/de-emphasis best practices. But the Roon team seems to have shelved or never gotten off the ground the user submitted writing project.
As for identification, Roon alone stands minimal chance of identifying albums mastered with pre-emphasis. Unlike HDCD, for example, no pre-emphasis flags are carried through to lossless audio files. Only ripper inserted or user edited metadata tags can flag pre-emphasis in audio files. For Roon to identify pre-emphasis after the fact, Roon would have to use its audio analysis functions to compare dynamic range metrics against those from albums known to have been mastered with pre-emphasis.
The Red Book audio de-emphasis standard is a known quantity. It is supposed to be an analog filter with two time constants: 15 µs and 50 µs. That provides the proper correction curve in both frequency response and phase response. An IIR filter should be able to model those characteristics.
AJ
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@brian Anything new on this front? I have some CDs with pre-emphasis and would like to be able to play them properly via Roon.
I hope you will say more. Inferior how? If you believe output quality is inferior, please elaborate.
I ask not to pick a fight, but I have access to a Windows plaform by rebooting my MacPro, and would do so if there were some benefit. Thx.
John, most of the best CD ripping and/or post processing tools as well as crowd sourced rip verification databases are Windows centric or even Windows exclusive. Some examples include dBpoweramp, CUETools, and foobar2000. Handling edge cases – namely, pre-emphasis and HDCD with peak extend – can be challenging outside of Windows.
AJ
Are there well-defined file tags that indicate when file needs de-emphasis processing?
I’m not terribly interested in the “compare dynamic range against dynamic range of some known recording” approach–at least not as an automatic thing, and I’m not convinced that the demand is there to build something so elaborate as a manual grooming tool. The right place to confront these details is at rip time, since that’s where you are meant to get metadata from the horse’s mouth.
The problem with doing it automatically is the potential for (and cost of) false positives–Looking at file tags and tracing that to an exact pressing of a CD that someone might have is generally not something we can do with perfect precision. In most of the files in the world, the information in the tags isn’t expressive enough to make the finer distinctions. We put a lot of work into getting it close enough that the errors aren’t too offensive or apparent too often, but it’s fundamentally a problem where you’re always going to have some rate of errors.
The problem with doing something like this automatically is that when there are false positives (i.e. we turn on the DSP inappropriately), we’ve done something really bad that could break peoples’ confidence in the product. Many people aren’t aware of this pre-emphasis topic at all, and won’t understand why we’re automatically making their music sound worse.
As I said before, we have no objection to looking at file tags and applying the filter automatically if that’s going to satisfy a need. That is a clean + easily explainable piece of product design that doesn’t have the risks I described above.
Foobar2000 adds a tag that says this:
PRE_EMPHASIS or PRE-EMPHASIS with value “1”, “on” or “yes”
dBpoweramp adds a tag called:
Pre-Emphasis
I am not sure what value it sets.
If the tag is present, the de-emphasis should be applied.
Sorry to flog a horse lying down, but i’d be interested in the filters primarily, are there any plans for implementing particular DSP-filters based on user defined (or ripper) tags?
I’m thinking primarily HDCD and digital files which are known to have pre-emphasis applied.
Actually, I doubt any HDCD has pre-emphasis. This was done in the early days of Red Book. Decoding HDCD would also be another good thing to do though.
A misunderstanding there, i wasn’t suggesting that HDCD had pre-emphasis.
It was merely two examples of filters that i’d like to see implemented.
(I have “decoded” my HDCD recordings with Foobar, but i dont want to keep two versions of files. Bit perfect is always best)
Please implement automatic de-emphasis filtering the way that you describe - that would be great and would save having multiple versions of the same album with manual de-emphasis applied.
Using a custom file tag would be perfect as no chance of automatically filtering tracks incorrectly.
Hello Brian,
I’m curious if this gained any traction and is planned for future release? Thanks.
We still plan to get to it at some point, but it is not yet scheduled for a specific release.
I think that properly decoding HDCDs is more important that handling pre-emphasis. Although HDCDs sound better when not decoded than CDs with pre-emphasis, there are MANY more CDs out there that are HDCDs. Maybe do both at the same time. For HDCD, use the tag “HDCD” set to “yes” or “no”.
I agree, but if it’s just a case of supporting the relevant tags, Roon can and should handle both.
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I do not find it challenging to complete these stated tasks on a Mac.
XLD for accurate CD rips and transcoding any file / codes types, DBpoweramp for HDCD identification and decoding (this software is not Windows exclusive), xACT for de-emphasis, DVD Audio Extractor for extracting audio from DVD and Blu-ray and Tag for metadata management.
These are just the Mac audio tools that I use regularly but there are many others available. In fact, I have never found a task that I can complete on Windows that I can’t complete to a least the same standard on a Mac.
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Pre-emphasis means you need to attenuate by:
So the correction is pretty massive, certainly more impactful than HDCD decoding.
For people reading this thread, check out the De-Emphasis filter that can be added to Roon as a Parametric Eq / High Shelf filter: