HydrogenAudio

Hydrogenaudio Forum => General Audio => Topic started by: mariois64 on 2020-04-08 04:22:01

Title: Does anyone know what this guy is talking about?
Post by: mariois64 on 2020-04-08 04:22:01
This post from an audio engineer on the Steve Hoffman forums claimed he completely removed digital distortion from an album for a vinyl release using a “digital footprint” Does anyone know what he’s talking about? Or how this can be applied? He doesn’t seem interested in sharing his secrets, but I did shoot him a message just in case..(https://imgur.com/a/KrzrJNg)
Title: Re: Does anyone know what this guy is talking about?
Post by: Chibisteven on 2020-04-08 06:04:25
Well, where's the link?

Also, no competent audio engineer would make up such an unfounded claim.

P.S. Hope you're not a troll or something because you only have one post and this is the first topic you posted here.  Kind of think you are one.
Title: Re: Does anyone know what this guy is talking about?
Post by: mariois64 on 2020-04-08 07:59:39
I posted an imgur link, no idea why it didn’t load. Rude to assume of me as a troll. https://imgur.com/a/KrzrJNg
Title: Re: Does anyone know what this guy is talking about?
Post by: Chibisteven on 2020-04-08 08:42:03
I posted an imgur link, no idea why it didn’t load. Rude to assume of me as a troll. https://imgur.com/a/KrzrJNg

Sorry about that assumption, I've seen people post stuff here and than run while everyone gets in argument that goes on for days.

I wouldn't take this so-called engineer seriously at all.  Sounds like this guy is trying to make a CD master he got for use with a vinyl production sound more up to his personal taste or preference because he finds the original master too objectionable based on perceived perception of dynamic range using a dynamic range meter.  The dude is an idiot.
Title: Re: Does anyone know what this guy is talking about?
Post by: Roseval on 2020-04-08 11:18:53
There might be something in it.
In fact using FFT to restore music is not uncommon e.g.

https://helpx.adobe.com/audition/using/noise-reduction-restoration-effects.html
https://books.google.nl/books?id=UTbTBwAAQBAJ&pg=PA141&lpg=PA141&dq=music+fft+restoring&source=bl&ots=pbkKJgV0R_&sig=ACfU3U1p7bTUJYj58nwKuOf3W446eek_Dg&hl=en&sa=X&ved=2ahUKEwj0kvDNzNjoAhXBGuwKHQ4sDoYQ6AEwAnoECAcQLg#v=onepage&q&f=false

Title: Re: Does anyone know what this guy is talking about?
Post by: DVDdoug on 2020-04-08 16:56:10
"Digital distortion" is a little misleading because it implies there's something inherently wrong with digital.   A lot of audiophiles and "audio engineers"* believe that.

It's kind-of a shame to go through the effort to improve the sound for analog vinyl.  ;)

And since this is apparently a digital era recording, it's too bad he couldn't go back to the original un-mastered mix and make a new  master rather than re-mastering and trying to un-do what was previously done.

There are lots of techniques & effects for mastering/re-mastering and I'm always suspicious when they are secretive.   Some people sell "magic effect" plug-ins without telling you how they work.   Usually they are using known algorithms but they don't give away  the details.

Mastering & re-mastering should improve the sound quality but re-mastering has gained a bad reputation because often excessive** compression and limiting is used.

As he mentions, there are known ways of increasing dynamic range but you can't perfectly un-do or reverse compression & limiting and usually the results are not very good.  (Maybe in this case he had some success.)

FFT (https://en.wikipedia.org/wiki/Fast_Fourier_transform) based techniques can be "dangerous" because in the real world it's not 100% reversible and you can get artifacts (undesirable side-effects).  But, I'm not saying it's always a bad thing and if he was able to reduce the distortion and improve the sound that's a good thing!

Also, note that the vinyl cutting and playback process will often increase the measured dynamic range (or crest factor (https://en.wikipedia.org/wiki/Crest_factor)) without actually changing the sound of the dynamics.   (To some extent the same thing happens with MP3 compression.***)    That leads many people to conclude that the vinyl is more dynamic (less compressed) than the digital version that the digital version even if they were made from the same master.   And of course, digital has more dynamic range capability…  (The dynamic range of analog is limited by the noise.)


* I put "engineers" in quotes because, although they are good a what they do, most recording/mixing/mastering engineers don't have an education in traditional science or engineering.

** Of course, that's my opinion.   The producers & mastering engineers, and apparently many listeners, consider the added compression to be an improvement.

*** Don't confuse file size compression with dynamic compression.
Title: Re: Does anyone know what this guy is talking about?
Post by: mariois64 on 2020-04-10 01:22:14
"Digital distortion" is a little misleading because it implies there's something inherently wrong with digital.   A lot of audiophiles and "audio engineers"* believe that.

It's kind-of a shame to go through the effort to improve the sound for analog vinyl.  ;)

And since this is apparently a digital era recording, it's too bad he couldn't go back to the original un-mastered mix and make a new  master rather than re-mastering and trying to un-do what was previously done.

There are lots of techniques & effects for mastering/re-mastering and I'm always suspicious when they are secretive.   Some people sell "magic effect" plug-ins without telling you how they work.   Usually they are using known algorithms but they don't give away  the details.

Mastering & re-mastering should improve the sound quality but re-mastering has gained a bad reputation because often excessive** compression and limiting is used.

As he mentions, there are known ways of increasing dynamic range but you can't perfectly un-do or reverse compression & limiting and usually the results are not very good.  (Maybe in this case he had some success.)

FFT (https://en.wikipedia.org/wiki/Fast_Fourier_transform) based techniques can be "dangerous" because in the real world it's not 100% reversible and you can get artifacts (undesirable side-effects).  But, I'm not saying it's always a bad thing and if he was able to reduce the distortion and improve the sound that's a good thing!

Also, note that the vinyl cutting and playback process will often increase the measured dynamic range (or crest factor (https://en.wikipedia.org/wiki/Crest_factor)) without actually changing the sound of the dynamics.   (To some extent the same thing happens with MP3 compression.***)    That leads many people to conclude that the vinyl is more dynamic (less compressed) than the digital version that the digital version even if they were made from the same master.   And of course, digital has more dynamic range capability…  (The dynamic range of analog is limited by the noise.)


* I put "engineers" in quotes because, although they are good a what they do, most recording/mixing/mastering engineers don't have an education in traditional science or engineering.

** Of course, that's my opinion.   The producers & mastering engineers, and apparently many listeners, consider the added compression to be an improvement.

*** Don't confuse file size compression with dynamic compression.

Yeah, that’s the kicker. The guy said the original masters are gone, so he had to work from that.
Title: Re: Does anyone know what this guy is talking about?
Post by: mariois64 on 2020-04-10 07:57:37
There might be something in it.
In fact using FFT to restore music is not uncommon e.g.

https://helpx.adobe.com/audition/using/noise-reduction-restoration-effects.html
https://books.google.nl/books?id=UTbTBwAAQBAJ&pg=PA141&lpg=PA141&dq=music+fft+restoring&source=bl&ots=pbkKJgV0R_&sig=ACfU3U1p7bTUJYj58nwKuOf3W446eek_Dg&hl=en&sa=X&ved=2ahUKEwj0kvDNzNjoAhXBGuwKHQ4sDoYQ6AEwAnoECAcQLg#v=onepage&q&f=false



Does Izotope’s RX 7 Declip use FFT?
Title: Re: Does anyone know what this guy is talking about?
Post by: j7n on 2020-04-10 20:12:24
Does Izotope’s RX 7 Declip use FFT?
I do not believe so. The author has described the method as "bidirectional least-squares autoregressive" interpolation. Stereo Tool employs a type of fourier transform omitting clipped samples, compensates for lost level, and then performs an inverse. There is significant spread of pre/post-echo from the linear phase filter around each repaired interval, but in RX only samples above the threshold are changed. But the restoration quality in Stereo Tool is better overall.

Noise reduction and other manipulations in the frequency domain can often do more harm than good if there is too frequent interpolation happening or the noise/distortion is of comparable level with the signal. Plastic warbling.