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Old 15th August 2015, 10:12 PM   #1
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Default De-mastering smashed recordings with Stereotool (Loudness War)

As most of you already know from the second half on nineties the discograhic industry began a Loudness War that ruined music enjoyment trading dynamic and distortion for loudness of CDs and digital downloads (more here).

The standard of dynamic range until 1994 was 13dB, at the start of year 2000 was 6-8dB and now is 4-6 dB.

The main tools used to destroy dynamic range are compressors and most of all limiters.

Hard limiters simply cut anything above a certain threshold, result is clipping with the associated (big) distortion and muffled sound.

Soft limiters uses more sophisticated approaches to limit dynamic range trying to avoid clipping and reduce distortion.

Sadly soft limiting can actually sound worse than clipping, particularly ealier algorithms.

The nice thing about hard clipping is that clipped waveforms can be somewhat recovered with different grades of success.

A full recovery is obviously impossible, clipping simply deletes a big amount of data but the recovered waveform is still pretty similar to the original one greatly reducing distortion.

Soft limited waveforms can't simply be de-limited since we don't know the algorithm used and the associated parameters.

The most effective and affordable tool I've found to recover what is possible and enjoy more recent music is Stereotool and his Perfect Declipper/Natural Dynamics.

In this thread I will share what I've found in the last two years experimenting with it.

I also expect feedback and sharing of other members findings about the argument.
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Old 15th August 2015, 10:34 PM   #2
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Default Perfect Declipper and Natural Dynamics

Keane - Somewhere only we know

Click the image to open in full size.

The Perfect Declipper algoritm reconstruct clipped waveforms using the remaining data, the result is a much less distorted waveform and recovers most of the original dynamic and bass.

Click the image to open in full size.

Default setting are not optimal, though.

Sadly most masterings are first compressed, soft-limited and at last hard limited.

So there are a not small number of songs in which you can recover clipped data but not soft-limited one.

Soft-limiters primary targets are percussions and the Natural Dynamics algorithms tries to de-limit them with a certain grade of success.

Click the image to open in full size.

The result is even more dynamic recovered.

In this case we pass from DR4 to DR11.
Attached Images
File Type: jpg 1.jpg (40.2 KB, 453 views)
File Type: jpg 2.jpg (56.2 KB, 452 views)
File Type: jpg 3.jpg (69.0 KB, 243 views)
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Old 15th August 2015, 10:52 PM   #3
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Default How to

In this example I'll use the free tool Audacity:

Click the image to open in full size.

The first thing we must do is to create headroom on the waveform to host recovered data amplifying the signal with a negative factor of 10dB.

Click the image to open in full size.

Sometimes, like in this case the original waveform has already some headroom, so we will use the 'New Peak Amplitude' to specify the 10 dBs.

Click the image to open in full size.

We can then apply Perfect Declipper/Natural Dynamics.
Attached Images
File Type: jpg a.jpg (302.4 KB, 242 views)
File Type: jpg b.jpg (16.7 KB, 242 views)
File Type: jpg c.jpg (230.5 KB, 243 views)
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Old 15th August 2015, 11:18 PM   #4
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Default Plugin settings

Set 'Operating Mode' to 'Expert'

Click the image to open in full size.

Click the image to open in full size.

Enable the Declipper

Click the image to open in full size.

Deselect 'Compressed input'

Click the image to open in full size.

Fine tuning of 'Restoration settings'

Click the image to open in full size.

Fine tuning of 'Detection' settings

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Optionally enable the Dequantizer, set input bit depth according the source waveform.

Click the image to open in full size.

Enable 'Natural Dynamics'

Click the image to open in full size.

Optionally enable 'Azimuth correction'

Click the image to open in full size.

Enable 'Hard limiting', just in case the reconstructed waveform exceeds headroom.

Click the image to open in full size.

Save all settings as a preset so that you can reuse them.
Attached Images
File Type: jpg a1.jpg (114.9 KB, 237 views)
File Type: jpg a2.jpg (104.1 KB, 234 views)
File Type: jpg a3.jpg (89.8 KB, 234 views)
File Type: jpg a4.jpg (134.0 KB, 232 views)
File Type: jpg a5.jpg (122.2 KB, 231 views)
File Type: jpg a6.jpg (163.6 KB, 231 views)
File Type: jpg a7.jpg (93.4 KB, 236 views)
File Type: jpg a9.jpg (149.3 KB, 233 views)
File Type: jpg a10.jpg (115.0 KB, 231 views)
File Type: jpg a11.jpg (103.4 KB, 229 views)
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Old 15th August 2015, 11:28 PM   #5
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How much better does it sound? Some information is just gone... or will sound strange I imagine with too much increased dynamics on things that weren't suppose to have it.
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Old 15th August 2015, 11:50 PM   #6
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Hi
There is a lack of use and understanding of companding, a
proven technique for capturing dynamic range beyond the
limitation of the mediums recording. But not only capturing
but replay as well. Is it any surprise that compressed recordings
exist as a whole generation has been brought up on compressed
formats.

It goes like this:
Some of the best recordings were done assisted by Dolby A
or DBX There are many exceptions, it is always a pleasure to listen how
well Frank Sinatra was recorded even via replaying via FM radio.
Only last week I was listening to a replay of Robert Johnson
recordings from the mid 1930's and marvelling just how much
dynamic had been captured particularly with his voice.

To get to grips with what audiophiles have missed
you have to study the work of David Blackmer
https://en.wikipedia.org/wiki/David_E._Blackmer

Then look seriously at the absence of companding in most audio
systems today.

My main system that is unlikely to change is
20 bit Pioneer CD player, with separate analogue power supply AD847 opamps
DBX 150x with LM4562 and LME49710
Yamaha CDRHD1500
My own LDR pre
Quad 306 x 2
ESL57, or Gale GS401a

It has been built around not accepting CD replay just with a CD player
rather to always use companding to improve upon CD replay.

The DBX White paper here:ftp://ftp.dbxpro.com/pub/pdfs/WhitePapers/Type%20IV.pdf
gives insight into how companding improves not only analogue
recordings but digital ones as well as digital has early overload
limiting dynamic range.

So if today's recordings are sounding compressed, they can always be
improved, the dynamic content being hidden, awaiting the use of
a good companding circuit. My favourite being Type 1 DBX it
seems to get audio replay pretty well perfect.

Cheers / Chris
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Old 15th August 2015, 11:55 PM   #7
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After applying the plugin you have the 'recovered' waveform:

Click the image to open in full size.

In this case we've gone from DR6 to DR14.

So far we didn't lost resolution since we worked at 32 bit resolution but the output, usually at 16 bit, will loose some details.

The waveform can (and should) further be optimized maximizing the waveform to 0.1-0.3 dB ceiling and applying dithering so to loose less details as possible.

StereoTool Clipper do a nice job but Wavearts Final Cut do better and have a professional ditherer too.

Also we should apply some soft-limiting (1 to 3 db under the max peak), the software don't necessarily recover all peaks.

A free and nice ditherer is MDA Dither.

Quote:
Originally Posted by Destroyer OS. View Post
How much better does it sound? Some information is just gone... or will sound strange I imagine with too much increased dynamics on things that weren't suppose to have it.
Results depends on source material but the de-mastered tracks will usually sound better, more dynamic, less distorted, with more defined bass and airy.

The resulting dinamics can be tuned to your taste applying the final limiting before dithering.

Also not all recoverings are so spectacular as in the examples, a lot of times you recover from 3 to 6 dB.
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Last edited by ClaveFremen; 16th August 2015 at 12:15 AM.
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Old 16th August 2015, 12:11 AM   #8
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Quote:
Originally Posted by Chris Daly View Post
So if today's recordings are sounding compressed, they can always be improved, the dynamic content being hidden, awaiting the use of a good companding circuit. My favourite being Type 1 DBX it seems to get audio replay pretty well perfect.
Hi Chris,

companding is another form of soft limiting which can be reversed using a compander.

A compander could enhance soft-limited waveforms and results will obvously be perfect only if the related technology was used during mastering.

But you'll never know it... and a compander can't do nothing about hard-limited (clipped) waveforms.
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Old 16th August 2015, 12:40 AM   #9
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Hi Dario
Entirely correct about the source material, which if clipped cannot be
improved upon.

Companding is a two part process, involving compression
followed by at opposite ratio of compression, expansion
and in the process dynamic range enhancement.

Nice work on unravelling this applying to PC based equipment
and suggesting more needs to be done.

Last edited by Chris Daly; 16th August 2015 at 12:44 AM.
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Old 16th August 2015, 12:46 AM   #10
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Quote:
Originally Posted by Chris Daly View Post
Nice work on unravelling this applying to PC based equipment
and suggesting more needs to be done.
Tnx

Feedback and members' results using described and other techniques is what I expect

Stereotool can be evaluated for free and audacity and MDA Dither are free so everyone can try and report here their impressions.
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