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Topic: Un-compressing music (Read 4713 times) previous topic - next topic
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Un-compressing music

Is there any way or by using filters or whatever, of getting rid of those compression effects in audio. The cd's sound so bad dont they. I have replay gained them all, but just wanted to see if there is way to get rid of compression effects too.

Thanks, Jay

Un-compressing music

Reply #1 –
you could always try to "decompress" or soften up the full range,
step by step, then build up the track again. A very time consuming and difficult task, because when you first compress it`s almost inreversabel.
But a few DX/VST plugins are realy good for remastering though,
for starters resample your material to 24bit, 32 should realy applie here
sinse most DX/VST host applications works in a 32bit mode.

There is a good reason why remixes are made from pre-master, not the downmix,
so if it had been me, i have went back to the store to get a earlier edition
if possible.

Un-compressing music

Reply #2 –
you may want to try a forum search - this question has been discussed multiple times and you can find lots of interesting information in other threads.

Short answer: the conclusion of all other threads was that its impossible to repair compressed music - you can only do a "pseudo-repair" to recover some of the peaks...... but thats basically all you can do. But compression affects much more than just "flattened peaks". Like i.e. dynamic range of the difference instruments. You cannot recover that.
Basically, its "what's lost is lost".

As i mentioned already - for more detailed information, search around in the forums.
I am arrogant and I can afford it because I deliver.

Un-compressing music

Reply #3 –
Unfortunately, compression/limiting is far more difficult to repair than clipping (and this is difficult enough).
I've never found any tool designed especially for this, could you please give more detailed information, FireStarter ?!
I've experimented with the normal dynamics processings, I tried to create something like a 'hard expander', but no success (in most cases). It seems that often infinities are used when limiting; no chance. If a soft limiter has been used (there is still something left of the 'different peak' audio information), repairing may be possible. But I've never used this actually, clip restauration already stresses me a lot.
I know that I know nothing. But how can I then know that ?
 

Un-compressing music

Reply #4 –
Well, why do they do this?

Un-compressing music

Reply #5 –
You refer to the music industry, mixing & mastering engineers, don't you ?
I'd also like to know. The most common opinion is that clipping and compression/limiting lead to LOUD CDs so that they sound louder on the radio, achieve more attention and are sold more often.
I know that I know nothing. But how can I then know that ?

Un-compressing music

Reply #6 –
is this true? They compress the sound so that it can be made louder, and sound better to idiots?

Un-compressing music

Reply #7 –
I believe that compressed audio can be broadcast more efficently than uncompressed.  I am not an engineer but I do remember reading an article a long time ago in AUDIO that said that.  Any broadcast engineers here to explain or refute this?  I would like to know for sure.

I do not like compressed audio as it is not true or faithful to the orginal sound.  But so few folks have ever heard live sound, or pure acoustic sound, that they are unable to detect the compression.  Kind of like Spinal Tap's amps going to "11" rather than "10" because "11" is louder than "10".  Rock on!   
Nov schmoz kapop.

Un-compressing music

Reply #8 –
precisionist, sorry for the late replie.

Quote
Unfortunately, compression/limiting is far more difficult to repair than clipping (and this is difficult enough).


In theory expansion with the exact contrary settings to the previous compression can reverse the previous compression. The problem is to find out the settings of the compression.

Quote
I've never found any tool designed especially for this, could you please give more detailed information


The WAVES C1 comp, comp-gate and C4 and the LinMB have presets called "Uncompressor". This might be a good starting point to experiment,
but in practice you will probably not be able to really reverse the process, it can be just the trial repair the worst.
Like i said, it is time consuming to strip a mix, for then to rebuild it.
In another thread i was asking if anyone have indept experience
with "4Front Master Bundle", thus the auxiter and sander seem to be good tools
for such a task.

Un-compressing music

Reply #9 –
Quote
is this true? They compress the sound so that it can be made louder, and sound better to idiots?

(jimhaddon)

Yes, that's the damn truth. It took me at least one year or so (I didn't know anything about HA.) to fully realize this issue; the truth is really painful. And almost all people in the world are these idiots.


Quote
  I believe that compressed audio can be broadcast more efficently than uncompressed. I am not an engineer but I do remember reading an article a long time ago in AUDIO that said that.

(boojum)

The only thinkable sense of compression/limiting: When lowering the available dynamic range, that might be sensible, for example going from 32bit to 16bit, recording from CD to analogue tape or broadcasting. The available dynamics of FM broadcasting are surely not more than 45 dB (foot- and headroom and usable dynamics). There might be some classical recordings that exceed this dynamic range. So the decrease in sound quality (less dynamics) equals the increase (a higher signal-to-noise ratio).


FireStarter, I don't care about late replies; I like to get replies at all, maybe a year later.
Quote
In theory expansion with the exact contrary settings to the previous compression can reverse the previous compression. The problem is to find out the settings of the compression.


Yes, but as I've already said before, in most cases it seems that infinite limiting ratios are applied. You can't reverse that process.
I know that I know nothing. But how can I then know that ?

Un-compressing music

Reply #10 –
Compressed music is a superior choice for a radio station because it means their signal can be heard further away from their broadcast tower. And because each additional mile of coverage means increasingly greater total square mileage (Pi*r^2), it is in the station's commercial interest to get that signal far.

However, the source material doesn't have to be compressed. Radio stations have dbx hardware compressors to do that work for them.

Un-compressing music

Reply #11 –
Quote
Well, why do they do this?

Because record label execs think a louder CD will sell more than one that isn't as loud when played in CD changers, store samplers, clubs etc. and will be more likely to get the attention of A&R reps, so they demand that mastering engineers do it or either have it taken to some upstart SoundForge kid who'll simply hard clip everything (which, oddly enough, is actually quite common in certain "professional" mastering engineers (*cough*Howie Weinburg*cough*George Marino*cough*)) with Bose monitors or have their job taken away.

Sometimes the producer will make the demand or, in rare cases, sometimes even the artist, but the general consenus is that major labels are the primary instigators of the whole thing.

Un-compressing music

Reply #12 –
Quote
The available dynamics of FM broadcasting are surely not more than 45 dB (foot- and headroom and usable dynamics). There might be some classical recordings that exceed this dynamic range. So the decrease in sound quality (less dynamics) equals the increase (a higher signal-to-noise ratio).

I used to listen to FM with > 70dB S/N, it was not a Clear Channel station for sure. Also compression can be used for sound improvement. Dolby A,B,C, DL, DPL all employ dynamic range compression/decomression.

Un-compressing music

Reply #13 –
Quote
I used to listen to FM with > 70dB S/N, it was not a Clear Channel station for sure.

(deaf)

How do you define signal-to-noise ratio ? Where do you live ? And what specific radio system are you using ?
70dB s/n ratio is impossible. I live in Germany and use a standard Hifi (cable antenna !) receiver. The signal goes from the analogue chinch output to my MD recorder, which converts the signal to digital, and then I directly record on HDD. (The MD recorder compresses (data reduction) the music, but it doesn't matter, since the quality is far superior to FM radio.) Then I compare the peak volume of signal and noise, at best the difference is around 40dB. (several radio stations and also a second receiver)

Quote
Compressed music is a superior choice for a radio station because it means their signal can be heard further away from their broadcast tower. And because each additional mile of coverage means increasingly greater total square mileage (Pi*r^2), it is in the station's commercial interest to get that signal far.

(mithrandir)
With cable and especially digital radio, this becomes irrelevant.
I know that I know nothing. But how can I then know that ?