Audio @ 24 Bit + Ripping in FLAC + EAC

[sirt]

Hi,

Well, I have very noob questions : how can one know whether a retail CD features music @ 24 bit which could be called a 'HD CD' ? Is is simply possible to extract WAV and check or can it be known 'in advance' without extracting anything ? Then my question is simply to konw which tool can indicate me whether contain on my CD is @ 24 bit ?

Can EAC rip accurately such CD in FLAC @ 24 bit ? I had some readings and it seems EAC only rips @ 16 bit (and also 44,1 kHz). Actually, it seems a 'tag' has to be recognized to take 24 bit in account.

Else, what free tool can be used to rip accurately CD in FLAC @ 24 bit (when applicable of course, I don't want to 'force' 24 bit if CD doesn't actually feature that) ?

[Ghitulescu]

Of course one can find out HDCD CDs... which BTW are not 24b, IIRC only 18b.
One can extract them with EAC as normal CDs, since they are compatible and play like they are, preferably with an HDCD decoder.
Or can be converted into 24b files.

About HDCD topics and related you should check hydrogenaudio or google. It's easy to find all you wanna know there.

[hello_hello]

foobar2000 (http://wiki.hydrogenaud.io/index.php?title=Foobar2000:Components_0.9#Converters)
Converters
HDCD Decoder (foo_dsp_hdcd) (http://wiki.hydrogenaud.io/index.php?title=Foobar2000:Components/HDCD_Decoder_%28foo_dsp_hdcd%29) This DSP component will decode HDCD data in any 16-bit PCM stream passed through it, resulting in 20-bit PCM.

CUETools (http://cue.tools/wiki/CUETools_Advanced_Settings:_HDCD)
Advanced Settings: HDCD
HDCD tab
Detect HDCD encoding
Check to enable HDCD encoding detection.
Decode HDCD to 20 bit {checkbox}
HDCD decoding is irreversible. Resulting files cannot be burned to the CD. 24-bit audio files are created, but the actual resolution is 20 bit.
Store as 24 bit "lossless" {checkbox}
When not using lossyWAV, extend to 24 bit for compatibility.

eac3to (http://www.videohelp.com/software/eac3to)
Command line option:
-decodeHdcd decodes HDCD source track (usually 16 -> 20 bit)

FFmpeg 3.1 (https://en.wikipedia.org/wiki/FFmpeg#Audio) has a HDCD data decoder.

As far as I know EAC can only rip HDCD as 16 bit, but the HDCD data is still there and it can be decoded as HDCD later on. You might need to do it that way anyway to verify the rip with AccurateRip. I'm not sure if it can be verified if it's ripped as 24 bit. The standard procedure for those married to EAC would probably be to rip with EAC and then convert to 24 bit with CueTools.

[sirt]

Well actually I tried that CUEtools. I'm not sure how to proceed. I ticked the following :

http://img11.hostingpics.net/pics/987007hdcd.png

In main menu I choose 'convert' as mode.

Then I load a flac in main menu and say Go : sometimes I get 'Audio format is not Red Book PCM..', sometimes 'HDCD not detected..'. Actually, as I said I have no idea whether these CD are supposed to be @ 24 bit natively.

Regarding eac3to, with same flac :

eac3to 01.flac 01_HD.flac -decodeHdcd
FLAC, 2.0 channels, 0:03:15, 16 bits, 1081kbps, 44.1kHz
Decoding FLAC...
Encoding FLAC with libFlac...
Creating file "01_HD.flac"...
There is no HDCD data to decode.
Aborted at file position 1572864.

Then it seems once again nothing HD is recognized. Perhaps it is true, but is it really sure potential HD information is kept somewhere ? These tracks have been ripped with EAC.

[Sparktank]

Do they have the HDCD logo on the disc?
https://en.wikipedia.org/wiki/High_Definition_Compatible_Digital

The disc needs to be an HDCD release rather than any old retail CD.

If it doesn't have the HDCD logo (or any other logo; SACD, etc), then it's just a regular 16-bit CD so no setting will rip at 24-bit.

If you want to do any extra processing or editing in Audacity or something similar, you can process it and then export as 24-bit.
But that's just for safety measures to protect your editing.
Realistically, 16-bit would sound the same if dithered.

[Ghitulescu]

There are no 24b CDs.

HDCD uses a trick to reallocate the last 2b so that the signal would appear to be 18-20b "equivalent".

The storage of HDCD in an universal manner would be to store the resulted WAV as 24b, or as normal in 16b but you need then a HDCD decoder.

[hello_hello]

I'd never really paid any attention to HDCD before, so I had a bit of a play.
CUETools does my head in a little. It seems to require a cue sheet or what it considers to be an album to look for HDCD data and if it finds any it converts every file to 24 bit lossless, even if they don't all contain no HDCD info. If none of them do it stops with an error. Best as I can tell anyway.

I couldn't get foobar2000 to convert the couple of test files I downloaded to 24 bit, despite the fact they were supposed to be HDCD. It just converted to 16 bit as usual. With the help of the HDCD plugin though, I could add HDCD info to my "what am I listening to" tab.

Without HDCD Info:
https://s24.postimg.org/kb0jm6l0l/test_1.gif

With HDCD Info:
https://s24.postimg.org/dylecchyd/test_2.gif

I'm assuming the foobar2000 plugin wasn't decoding the file in the second pic as 24 bit because there'd be no point. The transient filter constantly alternated between yes and no while the file played, but the peak extend and gain variables didn't change. I'll have to try to find some more samples to play with at some stage.

[sirt]

Indeed, my CD don't have any logo or anything else.

Ghitulescu, honestly I didn't understand what you said or I am not sure of what you explain. On the one hand, It seems you explain what HDCD does. Then, on the other hand, you also say there are no 24b CDs. I assume you wanted to say there are no 24b CDs but HD information can be, somehow, be stored in 16 bits/44.1 kHz but tracks and decoded afterwards.

I also understood it won't be possible to copy 24bit on a CD. Well, to start with, I need a HD CD. I am not sure to find that easely.

[sirt]

hello_hello, how do you know files you 'downloaded' are actually HD and can be decoded ? From what I understand, these files are 16 bits/44.1 kHz and you decoded HD and ended with 24 bits/44.1 kHz.

[hello_hello]

I found a sample labelled HDCD that hadn't already been converted to 24 bit, just to have something to test. The way I configured foobar2000 it doesn't display anything relating to HDCD unless the file contains HDCD data. If it doesn't it looks like the fist pic.

Yes the second one is 16 bit but it contains the HDCD info. After I managed to convince CueTools to convert it, it saw the HDCD info and converted to 24 bit flac. The foobar2000 plugin wouldn't convert it to 24 bit at all. I think that's because the the peak extension and gain options aren't enabled, and they're what effectively make it more than 16 bit when decoded as a HDCD. Without them I assume it's still just 16 bit, even though the transient filter option appears to be active.

The foobar2000 HDCD plugin has an option to "always halve the volume" when decoding HDCD files, or to halve it "only when peak extension is enabled". I assume halving the volume when decoding would prevent the extended peaks from being clipped when peak extension is enabled.
As best as I can tell, when CueTools detects a HDCD source it always halves the volume, which is probably why it always converts to 24 bit even when peak extension is not enabled. That makes sense though as it's geared towards processing whole CDs, so you wouldn't want it to halve the volume for some tracks and not others, and by converting to 24 bit you wouldn't lose any "resolution" compared to the 16 bit source, even if the volume is reduced.