Ripping HDCDs: Best practices?

[Porcus]

Re: Ripping HDCDs: Best practices?

The correct correction is 6, not 9. HDCD crams 9 dBs into 3 dBs on the disc, and it is the difference that is the peak extension.

Pre-emphasis: Display the Track Technical column. There is a setting where dBp can write a tag, provided you have a new enough version. (And, I think those will log it too. But in old days, you had to read it off Track Technical.)

How many? Among my non-classical ripped CDs, about 3 in a thousand. Includes Black Sabbath, Deep Purple, Pink Floyd and Roger Waters solo. And the darkwave label Cold Meat Industry was notorious.

Among my classical music: 34 out of 319 discs I have ripped. But 33 of them are from three boxed sets from the same label. 17 of them is even a single musician. So I likely didn't get a representative sample.

There is an issue about the relatively few CDs which do not have the pre-emphasis flag correctly in the TOC, merely in the subchannel for each track. dBpoweramp does not support this, I think; EAC used to, but André disabled a few features out of risk of being accused of copy protection circumvention; iTunes does, and CUETools does. That's likely a small fraction of the small fraction. (Likely, there are some CDs where pre-emphasis EQ was applied to the master but by error not flagged to the CD.)

[JustaNewUser]

Re: Ripping HDCDs: Best practices?

Thank you ver very much for your insights.
So, just a few more short questions:
If you would transcode I would imagine you would do that without the +6 amplification, is that all that option does? Just not amplify by 6db? Or is there more to the +6amplification?
According to your practice now (with lossless) you go even further to -9db does that mean to get the same effect I would have to go another -3db (maybe with a replay gain -3 for all tracks on an album) or even 6db+9db =15db lower? Or would you simply suggest (especcially seeing that this is just for some lossy transcoding) that the 6db are most often enough, and the clipping (if at all) would be minor and could be lessened even further through some simple replay gain analysis by the playback program; drawing from your extensive experience?

Thanks for the tip with the replay gain apply, I just did the calculation. I am more worried if the tags like: album art or simple name, genre, date changes, or custom fields could tarnish quality. Especially when something like album art goes from 50kb to 1000kb or more (or going the other way around)... I always thought that large changes involve rewriting the whole file... and if there is a hickup there (or the tag gets huge)... that could affect the playback or change the qulity in a major way (or induce some artefacts)...

Are there a lot of cds with pre-emphasis? how can poweramp display/mark them? I imagine that this could make quite a significant difference in playback. But that also means that a normal cd player would not play those cds correctly right?
Thanks again for your input...

[Porcus]

Re: Ripping HDCDs: Best practices?

1. Do you do this just to listen to a file or before a transcode to lossy?

I don't transcode to lossy Well the issue is that I started ripping using the HDCD component, not knowing what I know now. I have re-ripped a few (I have a bit of an idea of which ones they are, and whenever I encounter one in my boxes, it goes into the drive again), but I cannot remember having converted any of those CDs since then.
I would apply it upon transcoding to lossy, though.

2. a. So do you first take a lossless file, then take off 6db and then transcode with the HDCD option with the +6amplification.

The playback component I employ, will lower peak extension-enabled files by 6 dB to make room for the 6 dB peak extension.

3 a.Will it hurt to transcode HDCD files without PE with the option?
b. Will it matter at all quality wise?

It would be like playing it through a non-HDCD player or DAC. Peak Extension does squeeze the top 9 decibels into 3 upon recording/processing, and expand upon playback. That means, if you have a piece of music which is most of the time at 9 dB below max, and then it has 9 dB loud peaks, those peaks will only be 3 dB if you do not use the PE feature. So you lose dynamics. (And modern loudness-war victim albums are often constantly above the -9 dB mark ...)

4. And in general, have you ever been wowed by the HDCD features alone?

Never really tested. I made the mistake of decoding my HDCDs upon ripping ...

5. Oh and a real stupid question in a not related topic: If I change tags (and thus rewrite those) in a lossless (flac) file or change the filename, will (or can) that affect the quality or content?

There are tags that affect playback without affecting the signal-on-file. Most common: ReplayGain tags, which tells the player to adjust volume upon playback.
(Warning: Do not use the ReplayGain Apply DSP. That will change the file. The ReplayGain writes tags, the ReplayGain Apply adjusts the volume of the signal itself and writes it to file!)

There are other hacks that can affect playback, but you have to work to get them. For example, pre-emphasis CDs (that's a bl¤¤dy annoying thing!) which are recorded with EQ to be reversed during playback: dBpoweramp can tag these, and then there is a foobar2000 component (three different ones, actually) which can read the tag and apply EQ according to that instruction. But it does not change the file. (Indeed, if were to accidentally delete these tags, then there would be no way for me to tell the difference from inspecting the file ... except that I use a different codec and file format to guard against precisely that.)

[JustaNewUser]

Re: Ripping HDCDs: Best practices?

I use the kode54's HDCD component in foobar2000, with the option to halve volume when there is peak extension. That is, those tracks with PE first get reduced by 6 dB in order to make room to extend the peaks by +6 dB. That prevents clipping.

1. Do you do this just to listen to a file or before a transcode to lossy?

2. a. So do you first take a lossless file, then take off 6db and then transcode with the HDCD option with the +6amplification.
b. Or do you take off 6db and then transcode with the HDCD option without amplification?
c. Or do you simply transcode with the HDCD without the aplification (meaning that the HDCD option without +6 automatically gives you a quieter file without clipping anyway).

3 a.Will it hurt to transcode HDCD files without PE with the option?
b. Will it matter at all quality wise?

4. And in general, have you ever been wowed by the HDCD features alone?

5. Oh and a real stupid question in a not related topic: If I change tags (and thus rewrite those) in a lossless (flac) file or change the filename, will (or can) that affect the quality or content?

[Jeff Flowerday]

Re: Ripping HDCDs: Best practices?

Some points that might address your questions:

• At this time dBpoweramp does not have the ability to show whether a track is HDCD-encoded prior to ripping, can't at all show which HDCD features are enabled, and can only demonstrate that a lossless file is HDCD-encoded after applying the HDCD DSP, which will change the sample size from 16 to 24 bit.

The track technical information column will with high regularity tell you when a track is HDCD before ripping. But as you say won't tell you which features are enabled.

That said sometimes it doesn't indicate HDCD tracks when they are, and I think it's in regard to not reading enough track data on CD insertion, and has been discussed before on this forum.

[Porcus]

Re: Ripping HDCDs: Best practices?

Yes there are HDCDs not marked as such, as there was some common studio equipment (from Pacific, IIRC) which would write the HDCD flag even if the technician had no idea of it.

I use the kode54's HDCD component in foobar2000, with the option to halve volume when there is peak extension. That is, those tracks with PE first get reduced by 6 dB in order to make room to extend the peaks by +6 dB. That prevents clipping.

[JustaNewUser]

Re: Ripping HDCDs: Best practices?

Also thanks in this thread for your replies...
So again it would make the most sense to rip flac, then later transcode to mp3 with the HDCD option. And to make it simple, and get no clipping, always leave the + 6 off because the software increases the sound according to replay gain... Would it hurt (or help) any if you use the HDCD option even if PE is not used?
I am finding more and more of the HDCDs... Warner seemed to use it extensively with its remasters ca. year 2000: Tom Petty, Van Halen, Roxy Music... all have it, also Green Day and even some that don't have it labled like Pet Sounds from the Beach Boys....

If you had the +6 amplification option enabled and later just remove 6 db (gain) would this result in a file as if you had the HDCD option enabled but not enabled this +6 option or is there more to the amplification?

[Porcus]

Re: Ripping HDCDs: Best practices?

A: Yes. HDCD is flagged 'in signal', so as long as you don't touch the signal (e.g. lossy convert it), then it still has the same information.

Using HDCD.exe on a non-HDCD file would make no difference. All it will do, is scan the audio for HDCD code, and not find any.
However: 'non-HDCD' is a bit of an issue: there are CDs which are technically HDCDs, but yet uses no features.

That is, the music has this slight alteration in bit number 16 which is the flag that says 'I am a HDCD', and then it says 'and the following HDCD features are enabled:'
(with nothing enabled).

[JustaNewUser]

Re: Ripping HDCDs: Best practices?

Thanks a lot, so in (hopefully) closing:
A: when ripping to losless (flac) leave the option off (and you'll still get all the HDCD data), then you can play this with an HDCD player (ex. foobar) and get the full quality.
B:When later transcoding to, say mp3, use the HDCD option but best without the +6 ampl. as you can always adjust the volume or use replay gain later, and that will result in 1. not having to check for the PE but still always get the better quality and 2. not have (or at least minimize) clipping.

Regarding seeing wheather a CD is a HDCD: Wouldn't that show up, before ripping, in the column: Technical Info in the main screen of poweramp?
And most important, just to check for HDCDs is it safe to leave the feature on with non HDCDs or will it alter the files/data/quality of non HDCDs in any way??
Then as a recommended feature, it would be nice, when ripping to 2 formats (say flac and mp3), to have poweramp use no HDCD option on the lossless but the HDCD option on lossy (and as an option without the +6 amp)... in the future. That would save an extra later transcode step.
Oh and replay gain should be (optionally) calculated after the file has been written.

[tewill]

Re: Ripping HDCDs: Best practices?

Thanks. You are 100% sure on this?
I get 16 bit flacs without the option, 24 bit flacs with it. My understanding was that hdcd has 20 bits, surprising how those fit in a 16 bit flac file.
So then rip without and later transcode to mp3 with the option? With the +6 and likely clipping or without and then replay gain or turn the volume up? Or just transcode without the hdcd option?
So why then is there a hdcd option at all if the above is true?
And in closing: Will there be a noticable difference in the sound quality if you use the hdcd option?

Jeeesch, I hoped I coul just leave the option on at all times to at least see which cds are hdcds (sometimes it isn't even stated anywhere) or will poweramp determine this anyway (I found a tag HDCD in the metatag options that can be used)?

Some points that might address your questions:

• HDCD-encoding is essentially of value only when the PE feature is enabled.
  
  
• At this time dBpoweramp does not have the ability to show whether a track is HDCD-encoded prior to ripping, can't at all show which HDCD features are enabled, and can only demonstrate that a lossless file is HDCD-encoded after applying the HDCD DSP, which will change the sample size from 16 to 24 bit.
  
  
• Actually, the intention of HDCDs is to fit 20 bits into 16 bits, which should make it backwards-compatible with players that can't decode HDCD.
  
  
• If you plan on transcoding an HDCD-encoded lossless file to a lossy file (or ripping direct to lossy), it's highly likely the extra information will not be retained (It might be possible to retain the HDCD-encoding, but at the very least would entail using a lossy format and encoder that can encode to 24 bit as well as a player that can be set to output at greater than 16 bit, neither of which I believe is very straightforward.), so you would need to apply the HDCD DSP while (or prior to) transcoding. That said, again this is essentially only of value if PE is enabled.
  
  
• I imagine the HDCD DSP was included primarily for those who know they have players that can't decode HDCD.
  
  
• There definitely will be at least one noticeable difference if you use the HDCD DSP: the outputted audio will be quieter. As far as sound quality goes, it's likely there only will be a noticeable difference if PE is enabled, and even then YMMV, depending on your ear and the track.

[JustaNewUser]

Re: Ripping HDCDs: Best practices?

Thanks. You are 100% sure on this?
I get 16 bit flacs without the option, 24 bit flacs with it. My understanding was that hdcd has 20 bits, surprising how those fit in a 16 bit flac file.
So then rip without and later transcode to mp3 with the option? With the +6 and likely clipping or without and then replay gain or turn the volume up? Or just transcode without the hdcd option?
So why then is there a hdcd option at all if the above is true?
And in closing: Will there be a noticable difference in the sound quality if you use the hdcd option?

Jeeesch, I hoped I coul just leave the option on at all times to at least see which cds are hdcds (sometimes it isn't even stated anywhere) or will poweramp determine this anyway (I found a tag HDCD in the metatag options that can be used)?

[EliC]

Re: Ripping HDCDs: Best practices?

Hi,
thanks for all this info in these posts but correct me if I am wrong:
if you rip *without* the HDCD option the lossless flac file will be 16 bit and no more; thus the extra bits of a HDCD would be lost.

You are wrong. The info is all still there, and the original 16 bit PCM files ripped from the CD, stored in WAV and compressed with lossless compression (FLAC) can still later be run through the HDCD DSP.

You can verify this yourself.

Rip an HDCD with and without the HDCD DSP

Use the DSP on the one ripped without and see that they are they same.

This is basically what dB does anyway.

The better (best for lossless) practice is as stated, rip WITHOUT the HDCD dsp!

[JustaNewUser]

Re: Ripping HDCDs: Best practices?

Hi,
thanks for all this info in these posts but correct me if I am wrong:
if you rip *without* the HDCD option the lossless flac file will be 16 bit and no more; thus the extra bits of a HDCD would be lost. So how could you later transcode or play back such a file and expect that a HDCD capable player would somehow restore those lost bits that are not there? I thought the HDCD option ensures that the flac will be of a higher bitrate capable of storing the extra data.

If my assumptions are correct, let me explain my thoughts/questions regarding the HDCD option:
What do we want when we rip a CD? The best sounding, preferably lossless, most accurate file that resembles the original, we can get.

From what I understood the options regarding HDCD disks which make sense would be to either:
1. Rip to a lossless (ex. flac) file with the option of HDCD with +6 amplification.
2. Rip to a lossless file with the option HDCD without the amplification.
3. Rip to a lossless file *without* the HDCD option.

1. Could result in some clipping which is hard to discern, but has (slightly and not audiable) altered (amplified) the data.
2. Would result in a file with less volume.
3. Would result in a file that misses/discards the extra data of the HDCD thus resulting in a file that is no longer lossless.

Now correct me again but it seems that I would rather take a slight chance of a hard to discern change (clipping) than have a less than lossless file. So option 1 would be better than 3.
Since we all have a volume control, I think option 2 would even be better: no clipping and only a little quiter which we all can correct easily. (And to those that say my mobile player can't play those files at an adaquate volume, I would reccomend quality headphones and possibly a portable amp, not that listening to music on the street requires a super hi-def lossless file anyhow)

Regardless, the ReplayGain can always be calculated at a later time (by almost any modern program) and increase (or decrease) volume accordingly. You may get a wrong gain value when using this option in conjunction with the HDCD option, at the time of the rip, but that can always be corrected by recalculating the value (no loss of data or change in quality). Then almost all media players (including the oh so popular itunes) can increase the volume of the HDCD rips that have a lower volume, with no damage to the integrity of the lossless rip.

So in summary: I think ripping *without* the +6 ampl. but with the HDCD would probably result in the best quality, with the only caveat of it being lower in volume but with no clipping, distortion or loss of data. And to counter that, use the volume knob or/and replay gain.
This would probably be the easiest and most compatible option for fast ripping, just leave it on, get all the data and lossless files.

I hope this is somewhat correct.

I have a question though: when I leave the option HDCD on while I rip non HDCD discs, will that change anything at all in the files for those discs?

Also: when ripping with the HDCD option and creating both flac and mp3 files at the same time, would it then be better to use amplification specifically for the mp3s? I mean with replaygain I suppose you could just get those up in volume as well..

Thanks for your clarification on this.

[garym]

Re: Ripping HDCDs: Best practices?

Thanks tewill. This is very clear. Thanks again for all the detail you've provided in this thread.

[tewill]

Re: Ripping HDCDs: Best practices?

Quick (I think, or maybe just naive) question. If I have an HDCD that was ripped to FLAC without use of the HDCD dsp, is it true that I can:

1. convert from FLAC to FLAC, adding the HDCD DSP in this conversion, and not *also* applying ReplayGain

Yes, this is what I would recommend.

2. Afterwards apply ReplayGain to the newly created FLAC files

And yes again. Reason being that if you apply the ReplayGain DSP at the same time as the HDCD DSP, the calculated ReplayGain values are based on the un-decoded HDCD audio. When you apply the ReplayGain DSP on the newly created FLAC files, the values are calculated based on the decoded HDCD audio. That said, I'd still recommend you not use ReplayGain for either HDCD-encoded or decoded files, as it might negatively affect the benefits of HDCD encoding (e.g., The PE feature extends the peaks, and decoding the HDCD audio decreases the volume by 6 dB to add more headroom, to ensure you both can hear this as well as to prevent clipping. As the purpose of ReplayGain is to tell a player to increase or lower the volume depending on the relative volume of a track, it can therefore affect decoded HDCD audio. Without ReplayGain, the volume of a decoded HDCD track will be a bit lower, but this won't be as noticeable with PE enabled, and hopefully you'll be paying more attention to how much better it sounds than the fact you might have to turn the volume up a bit).

I realize that these new FLAC files would no longer be lossless, but I'd be able to play them with non-HDCD players. And to be clear, if I play my original FLAC files (that were NOT ripped using HDCD DSP) through a player that is capable of handling HDCD decoding, they should play as HDCD disks.

The new FLAC files are still lossless, but the volume has been decreased by 6 dB. And, unlike the ReplayGain DSP, this volume change was effected by altering the audio in the files, so even though the files are still lossless (in that audio data was not lost), they have been permanently modified. And, you should still be able to play HDCD-encoded files on players that can't decode HDCD, as HDCDs were designed to be backwards-compatible; in such a case you'll hear the music but the HDCD will not be decoded. Last, yes, if you play HDCD-encoded files with a player that can decode HDCD, the HDCD should be decoded. I like foobar2000 because with the HDCD decoder add-in you can not only play HDCDs but configure the UI to show you both that the file is HDCD-encoded and with which features.

That is, it is NOT important that I apply HDCD DSP during *ripping* as opposed to simply applying it during a FLAC to FLAC conversion.

I'd say your "NOT" is misplaced here, as I'd instead say it is important that you NOT apply the HDCD DSP during ripping because it physically modifies the file, unless of course you don't want an exact copy of the HDCD or don't mind re-ripping in the future.