Ripping HDCDs: Best practices?

[mville]

Re: Ripping HDCDs: Best practices?

If your player can decode HDCD audio, I wouldn't use ReplayGain on any track that is HDCD-encoded. Whether you remove the ReplayGain tags is up to you; you could instead do something else like disable ReplayGain in your player. I'm not sure if this is the case with foobar2000, but some players automatically disable ReplayGain when decoding HDCD audio.

tewill, thanks for the clarification (I bow to your superior expertise when it comes to HDCDs). I've got a couple of questions if you don't mind.

I have my ripped my HDCD Audio CDs without using the HDCD DSP and there are no ReplayGain tags, for use in foobar2000 with the HDCD component.

I now wish to convert these HDCD tracks to mp3 for use in my iPod, using the HDCD DSP and adding ReplayGain/iTunNorm tags.

Regarding the HDCD DSP, do you recommend selecting the +6 dB Ampilification option?

Regarding the ReplayGain/iTunNorm tags. Is this done after converting to mp3. i.e. Is this a 2-step process. First convert to mp3 using HDCD DSP, then convert again adding ReplayGain/iTunNorm tags?

[tewill]

Re: Ripping HDCDs: Best practices?

tewill, thanks for the clarification (I bow to your superior expertise when it comes to HDCDs). I've got a couple of questions if you don't mind.

I have my ripped my HDCD Audio CDs without using the HDCD DSP and there are no ReplayGain tags, for use in foobar2000 with the HDCD component.

I now wish to convert these HDCD tracks to mp3 for use in my iPod, using the HDCD DSP and adding ReplayGain/iTunNorm tags.

Regarding the HDCD DSP, do you recommend selecting the +6 dB Ampilification option?

Regarding the ReplayGain/iTunNorm tags. Is this done after converting to mp3. i.e. Is this a 2-step process. First convert to mp3 using HDCD DSP, then convert again adding ReplayGain/iTunNorm tags?

This is what I would recommend when transcoding HDCD-enabled lossless files to a lossy format:

1. If peak extend is enabled, apply the HDCD DSP while transcoding, with the +6 dB amplification option *unchecked*. Otherwise don't apply the HDCD DSP while transcoding. From my experience, applying the HDCD DSP while transcoding doesn't appear to affect the source lossless files. You could also apply the HDCD DSP to the lossless files prior to transcoding, but again note that doing so will physically alter the audio data in those files.

2. Don't write ReplayGain tags for the transcoded files that had PE enabled, but you could do so for those that didn't have PE enabled (while transcoding, if that's what you usually do), as essentially you'd be treating them as if they weren't HDCD-enabled.

Note that when you play the transcoded lossy files that had PE enabled and for which you applied the HDCD DSP, they likely will sound quieter, especially if you're used to the volume being normalized across tracks. I wouldn't use ReplayGain for these files because there is the possibility that the gain will be increased enough to cause clipping, which will negate the benefit of the PE feature.

[Goes To 11]

Re: Ripping HDCDs: Best practices?

Circling back on this, here are the best practices I came up with for ripping HDCDs:
[LIST=1][*]In general, rip HDCDs to a lossless format and don't apply the HDCD DSP.
[LIST=a][*]You also shouldn't write ReplayGain tags on these lossless files because:

1. ReplayGain can negatively affect the PE and LLE features.
   
   
2. When you use the ReplayGain DSP, values are calculated based on the un-decoded HDCD audio, and these values won't be valid once the files are decoded by your device.

I am feeling pretty bad that I just can't get my head straight on the best way to rip HDCD for my purposes--which is why I started a thread called HDCD for Dummies a while back. My main purpose is to listen to random mixes on a Squeezebox Touch, and SBT does not decode HDCD. So in my "Dummies" thread, Spoon said in post * 5 the best thing to do would be to rip with the HDCD DSP effect, with the +6 db box NOT checked, and use a Replaygain tag to normalize volume on playback. http://forum.dbpoweramp.com/showthre...or-it-was-used

But above, tewill, you say the opposite about Replaygain. And in another thread I found the comment to rip first with the HDCD DSP, then add a Replaygain tag to the file, which I think is meaning a two-step process:

IMHO +6dB should NEVER be checked when decoding HDCDs to 24-bit FLAC files. HDCD decoding is a non-reversible process, so it is better to leave the amplification setting off.

Your files will be 6dB quieter, that is true, but with replay-gain enabled during playback on any software, this overcomes any issues. I would highly recommend adding the replay-gain (scanning only, not applying) DSP after the HDCD decode DSP. This will re-scan the replay-gain value for equal-volume playback on all devices.

http://forum.dbpoweramp.com/showthread.php?24186-New-Hdcd-Default-question&p=135128&highlight=*post135128

Any comments on what my "best" practice should be would be appreciated. What I've been doing is following Spoon's advice, but now I'm wondering if I should be doing is adding the Replaygain tag in a second step.

[garym]

Re: Ripping HDCDs: Best practices?

In summary, one really needs two versions of the FLAC files. There is no way that a single approach can satisfy the competing issues.

One version without using HDCD DSP (so they are truly lossless, and it may turn out one day in the future one has a PLAYER that will automatically deal with HDCD files)

A second version USING the HDCD DSP, so they can be played through non-HDCD players (such as Squeezebox players).

p.s. I have quite a number of HDCD files (mostly grateful dead releases). I've heard them on good HDCD CD players in a good system. They don't sound any better (to me) than playing the lossless FLACs through the same system via a Squeezebox player (flacs made without the HDCD DSP). So the entire issue is sorta "meh" to me. That said, given my age (late 50s), the hundreds of live concerts in the 1960s/70s I attended with no ear protection (front row with The Who, 1971 anyone?), my hearing is not the greatest, particularly above 14kh.

[Goes To 11]

Re: Ripping HDCDs: Best practices?

Gary, the point you make about hearing loss is a good one---I'm probably worrying about something that will be inaudible for me. My final straw, of all things, was a Cranberries concert in approximately 1993 which I didn't expect to be seriously loud. Not only were they and their opener the loudest bands I've ever heard, they were so loud they were actually painful. Ever since that night the ringing in my ears has never gone away. I hate to think about what the constant earbud users have to look forward to.

OK, to get back to the point. Gary, do you agree or disagree with Tewill's statement "When you use the ReplayGain DSP, values are calculated based on the un-decoded HDCD audio, and these values won't be valid once the files are decoded by your device."

Thanks for your knowledgeable advice.

[garym]

Re: Ripping HDCDs: Best practices?

Gary, the point you make about hearing loss is a good one---I'm probably worrying about something that will be inaudible for me. My final straw, of all things, was a Cranberries concert in approximately 1993 which I didn't expect to be seriously loud. Not only were they and their opener the loudest bands I've ever heard, they were so loud they were actually painful. Ever since that night the ringing in my ears has never gone away. I hate to think about what the constant earbud users have to look forward to.

OK, to get back to the point. Gary, do you agree or disagree with Tewill's statement "When you use the ReplayGain DSP, values are calculated based on the un-decoded HDCD audio, and these values won't be valid once the files are decoded by your device."

Thanks for your knowledgeable advice.

I'm not sure, but I *think* I agree with Tewill's statement. But because I'm NOT using the HDCD DSP and I'm NOT playing through a device that decodes HDCD, I do use RG tags. But this is still consistent with Tewill's statement I think. (p.s. I use various Squeezebox hardware players, transporter, touch, etc.)

[tewill]

Re: Ripping HDCDs: Best practices?

I subscribe to the "rip once" philosophy, so strongly agree with garym that if your player doesn't decode HDCDs and you want to apply the HDCD DSP to compensate, you should do so to a copy of the original lossless audio. I like to have a perfect copy of all my CDs, and just thinking about re-ripping even one makes me shudder.

Again, I personally don't think ReplayGain should be used with decoded HDCD audio (regardless of how it's decoded, including via the HDCD DSP), as I'd want to ensure there's enough headroom for HDCD audio with PE enabled. That said, you could always analyze the audio with and without ReplayGain and see if there's any clipping.

If you want to write ReplayGain tags to HDCD-encoded audio, to my knowledge there is no way for dMC to decode the HDCD audio temporarily, calculate ReplayGain tags based on the decoded audio, then output the original HDCD-encoded audio with ReplayGain tags for the decoded audio. You could probably do this by hand, however: i.e. apply the HDCD DSP, then apply ReplayGain, copy the ReplayGain values, then manually write ReplayGain tags with those values to the original HDCD-encoded files. Seems like it would work, but I'm not sure.

All this said, after doing a good deal of research and thinking about HDCDs, I think this is all moot, as 1) such a small number of most people's CDs are HDCD-encoded, 2) the value of HDCD-encoding is essentially only realized for those HDCDs with PE enabled, and 3) YMMV (regardless of age, garym) as to whether you can even hear the value of PE. In fact, I think the most noticeable aspect of decoded HDCD audio is that it is quieter than it is when it's not decoded. If this is bothersome, and you are using a player that decodes HDCD, it might make sense to apply the HDCD DSP and either use the +6 dB option or ReplayGain to make the audio louder, and not worry about any potential clipping.

In your case Goes To 11, as you're not using a player that decodes HDCD audio and seem more interested in volume normalization, I personally would forget you even have HDCDs and rip and apply ReplayGain tags as you would for any other CD.

BTW, if you're using Logitech Media Server with your Squeezebox Touch, and are running it in a Windows environment, there are some mods to decode HDCD "on the fly":

My digital audio guide - SqueezeCenter modded!

On-the-fly HDCD *and* CD deemphasis

[Goes To 11]

Re: Ripping HDCDs: Best practices?

Tewill, thanks for commenting, and for the tips about modding LMS to decode HDCD "on the fly." Don't know if I'll try, but good to know I have that option.

Gary, going back to something you said--first you said to rip "A second version USING the HDCD DSP, so they can be played through non-HDCD players (such as Squeezebox players)" and then in your next post you said "I'm NOT using the HDCD DSP and I'm NOT playing through a device that decodes HDCD, [so] I do use RG tags." To me, it seems that what you're doing in practice (not using the HDCD DSP) contradicts your first statement, so I think I'm still confused.

I re-started thus discussion because of ripping a Paul Simon CD the other night that is HDCD--I think I have ripped at least 30 or so now from my collection that are. I think that where I am on this (and yes, I will be re-ripping, ugh) is that I am going to rip one copy with nothing applied, so as to have a perfect archival copy for all-time future purposes. Then I am going to rip with and without every combination of the DSP HDCD and ReplayGain tags, and listen to the results for comparison. If I perceive one as better, that's the combination I'll go with. I'm reluctant to use the +6 db extension because so many have said they hear audible clipping with it, and Spoon's recommendation not to. But maybe I should throw that into the comparison as well.

Thanks for the help, guys.

[garym]

Re: Ripping HDCDs: Best practices?

To be clear, I do what tewill recommended:

"I personally would forget you even have HDCDs and rip and apply ReplayGain tags as you would for any other CD."

I rip to flac like any other cd and add RG tags. I do nothing special for the HDCDs.

[2Bdecided]

Re: Ripping HDCDs: Best practices?

If you have decoded HDCD audio saved to lossless or lossy files, you can use ReplayGain just as you would with a regular CD rip or hi-res PCM download. You can scan those files to calculate ReplayGain values, and enable ReplayGain in your audio player so that it uses those values to match loudness during playback if/when you wish.


Default ReplayGain playback will cause clipping on a minority of regular CDs if you don't enable clipping prevention in the player. A highly dynamic HDCD with PE is no different. In both cases, you should use clipping prevention to avoid clipping. FWIW I always use ReplayGain in album mode with clipping prevention.

If you don't want to use ReplayGain at all, that's fine.
If you want to write tags and never use them, that's fine.
If you want to write tags and use them in a ReplayGain-aware player during playback, that's fine.
If you want to apply the ReplayGain change to the actual audio data, that's fine too.

Any advantages, issues, things-to-remember, and disadvantages with these different approaches (and there are several) apply exactly the same to files containing decoded HDCD audio as they do to rips from regular CDs or hi-res PCM downloads.

That's it. On the subject of using ReplayGain with files that contain decoded HDCD audio, there's nothing else to say.


As for ReplayGain with as-ripped (not decoded) HDCD data, or (the much smaller problem of) ReplayGain with (not de-emphasised) pre-emphasised tracks: that's up to you. I keep the as-ripped lossless versions of these tracks filed away separately out of curiosity, but only have the decoded/de-emphasised versions of them in my main library.

Hope this helps.

Cheers,
David.

[calestyo]

Re: Ripping HDCDs: Best practices?

Hey.

Any new developments here? In especially with regards to a decoder which scans the whole image, correctly identifies the used features and decodes as/if appropriate? My "strategy" would be as well to keep a lossless copy extracted as is from the CD (i.e. with 16bits and HDCD encoded within),... but I don't really agree that it's best to rely on software decoding this later. The fact is, HDCD is dead (assuming it was ever alive ;-) )... in 10-20 years now one will bother to write software which contains any decoder for it - so from that POV it's actually reasonable to have a second copy of the image in question which *is* already decoded. But AFAIU this thread there is no software which can really fully decode hdcd, and even if these unimplemented features are not used the whole thing seems to be quite vague.

Cheers,
Chris.

btw: It seems ffmpeg has also *some* HDCD decoding features ... any knowledge about those?