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MP3 Compression??
Old 16th November 2007
  #1
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lakeshorephatty's Avatar
 

MP3 Compression??

I think being allowed to call mp3's "compressed" is a terrible mis-nomer..

question.. do you think the average person thinks they can get the data back if they want??

data compression

A technique in information technology by which the same amount of data is transmitted by using a smaller number of bits; for example, by replacing a string of ten repeated digits with a command to repeat the digit ten times.




Russell
Old 16th November 2007
  #2
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narcoman's Avatar
 

Quote:
Originally Posted by lakeshorephatty View Post
I think being allowed to call mp3's "compressed" is a terrible mis-nomer..

question.. do you think the average person thinks they can get the data back if they want??

data compression

A technique in information technology by which the same amount of data is transmitted by using a smaller number of bits; for example, by replacing a string of ten repeated digits with a command to repeat the digit ten times.




Russell
No - because thats an incorrect definition. Back in my maths research days we used to refer to signal squirts of reduced data as compressed - this in the late eighties and early nineties way before mp3 and the like. None lossy transmission was called coded - hamming code and the like.
Old 16th November 2007
  #3
I'll use perceptual encoding when I'm being fussy about clarity.


If we (as putative experts in relation to the general population) use an ambiguous term like compression to refer to lossy encoding we risk further confusing the public who are already somewhat uncertain about the term compression with regard to audio compression/limiting.

And since at least some of us are trying to communicate to the general public the issues surrounding both lossy perceptual encoding as well as the issues relating to audio compression/limiting in the quest for competitive loudness -- any clarity of expression we can bring to the issue is probably welcome.
Old 16th November 2007
  #4
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crufty's Avatar
The average person: yes.

If I record a message in 24-bit 192khz stereo wav, and compress it to mono 32kb, when I play it, I can hear my voice...have I really lost anything?

Of course, if I want to listen to pink floyd, or classical music, then perhaps I have...


for most people wanting to listen to music on their ipods...have they lost anything--can they really not retrieve the data (the essence of sound) that they want?
Old 16th November 2007
  #5
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I don't think it is terrible at all. You end up with less data than you started with but a fair approximation of the original (E&OE!).

That's compressing something right? If I compress a grape I don't expect to be able to get it back somehow.

Who cares if someone thinks they can make an mp3 with an alesis 3630?

What would you call it?

'Audio Decimation' gets my vote, sounds kind of technical but tells the whole story.
Old 17th November 2007
  #6
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mmcfarlane's Avatar
 

Quote:
Originally Posted by lakeshorephatty View Post
I think being allowed to call mp3's "compressed" is a terrible mis-nomer..

question.. do you think the average person thinks they can get the data back if they want??

data compression

A technique in information technology by which the same amount of data is transmitted by using a smaller number of bits; for example, by replacing a string of ten repeated digits with a command to repeat the digit ten times.



Russell
Your definition is of a lossless compression. Lossless compression is used a lot in computer programs, for example the popular .zip file format.

There are lossy compression schemes and lossless compression schemes. Lossless compression schemes don't loss any information. Lossy ones do loose information.

mp3 is a lossy compression technique. The amount of loss depends on the bitrate of the .mp3. 64k is very lossy and sounds like crap for recorded music. 256kbps is still lossy, but not as lossy, and it sounds better than 64kbps.
Old 17th November 2007
  #7
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OK, this is interesting. I have always thought I heard compression of levels in every instance of lossy compressed data. Was that just my ears playing tricks on me?
Old 17th November 2007
  #8
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Quote:
Originally Posted by mmcfarlane View Post
mp3 is a lossy compression technique. The amount of loss depends on the bitrate of the .mp3. 64k is very lossy and sounds like crap for recorded music. 256kbps is still lossy, but not as lossy, and it sounds better than 64kbps.
What is that that we loose explained in audio language?...Dynamics...frequencies?
Thanks!
Old 17th November 2007
  #9
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Let's call it superfluous data reduction.
Old 18th November 2007
  #10
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Quote:
Originally Posted by joaquin View Post
What is that that we loose explained in audio language?...Dynamics...frequencies?
Thanks!
You will loose frequency content with the mp3 format. I'm pretty sure you loose dynamic range also.

Take a CD and compress it at different mp3 bitrates and listen for yourself. Depending on your monitoring setup you may find around 500kbps is a pretty decent sound and compromise for saved storage capacity. Through your laptop speakers or cheap headphones 256kps is probably adequate.
Old 18th November 2007
  #11
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Quote:
Originally Posted by lakeshorephatty View Post
I think being allowed to call mp3's "compressed" is a terrible mis-nomer..

question.. do you think the average person thinks they can get the data back if they want??

data compression

A technique in information technology by which the same amount of data is transmitted by using a smaller number of bits; for example, by replacing a string of ten repeated digits with a command to repeat the digit ten times.




Russell
I agree, I think MP3's shouldn't be referred to as being compressed, the process should be referred to as suckified.

Suckified: To drain or suck the life out of an otherwise pleasant sounding audio recording.

In the interest of saving disk space, (Disk space in this context can also refer to Non-volatile memory) an individual uses suckification to remove frequencies deemed as superfluous by a group of engineers interested in saving disk space when disk space was quantitatively lower than current standards circa late 2007.
Old 18th November 2007
  #12
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Quote:
Originally Posted by bcgood View Post
In the interest of saving disk space, (Disk space in this context can also refer to Non-volatile memory) an individual uses suckification to remove frequencies deemed as superfluous by a group of engineers interested in saving disk space when disk space was quantitatively lower than current standards circa late 2007.
Disk space is less of an issue now than efficient network transmission. Still takes a while to send a 25-40mb file through the internet. If everyone as doing it, for the amount of audio that flies around the net, broadband would run at dial-up speeds.

Though, my 200gb of ripped CDs on my computer would balloon to a 1tb if they were all encoded with lossless compression, and almost 2tb with uncompressed files. That saves me about $600, so disk space does not go unconsidered.
Old 18th November 2007
  #13
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Quote:
Originally Posted by bcgood View Post
I agree, I think MP3's shouldn't be referred to as being compressed, the process should be referred to as suckified.
Good call. Thats must be the correct term I beliave.heh
Old 18th November 2007
  #14
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Quote:
Originally Posted by mmcfarlane View Post
You will loose frequency content with the mp3 format. I'm pretty sure you loose dynamic range also.

So how does it work? What are the criteria behind the selection of Info (Data) to be disposed in favor of file size?
Thanks.
Old 18th November 2007
  #15
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one thing i'd like to mention is i do think mp3's are useful. I may only encode at 192 in some cases because i feel most of the "loss" has already occured in some music getting it into the digital domain in the first place (old cd digital transfers of classic albums).

And the bit rate doesn't have to be exceedinly high for me, because the amount of time during even focused friday night listening i focus on the medium no matter what it has done is exceedingly small. Case in point the new radiohead. I failed to get the discbox as of yet but have listened to the album numerous times at the 160k they released it at (paid $6 by the way, i thought that was fair) because i think its a great collection of songs, and I have never heard more detail than that on this recording!

If i don't know what i'm missing, under certain cases it can sound great! that's a concept that can throw some for a loop. Sure shimmery flanged cymbals, lispy vocals, lack of bass definition and reverb tails can give it away but above that point which in good encodings case can now be 192ish or somewhat higher, if you've never heard the full bandwith, how do you know you're not hearing the intended sound?

Just more food for thought...

Russell
Old 18th November 2007
  #16
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joaquin's Avatar
 

Quote:
Originally Posted by lakeshorephatty View Post
If i don't know what i'm missing, under certain cases it can sound great! that's a concept that can throw some for a loop. Sure shimmery flanged cymbals, lispy vocals, lack of bass definition and reverb tails can give it away but above that point which in good encodings case can now be 192ish or somewhat higher, if you've never heard the full bandwith, how do you know you're not hearing the intended sound?

Just more food for thought...

Russell
Interesting perspective. "Ignorance as bliss".
Personally, unless I'm working, or purposely enjoying a work of art, I usually listen to music in inadequate systems at noisy places…It has never stopped me from singing along or discover and celebrate “the magnifique” production qualities behind an Album!?

Here’s a link to wikipedia MP3 - Wikipedia, the free encyclopedia
Old 18th November 2007
  #17
Quote:
Originally Posted by travisbrown View Post
Let's call it superfluous data reduction.
One man's superfluity is another's necessity... heh


That said, I have a much bigger problem with the unmusical effects of competitive loudness limiting/compression than with even a 128 kbps Mp3.

Most of my everyday listening is to streaming WMA's that have an average bit rate around 192 kbps... I feel it services a good recording pretty well. Is it indistinguishable to a trained ear listening carefully? On really well recorded material, probably not in most cases. On a lot of what's out there in the catalogs, it's more a judgment call. An advanced format like AAC and WMA sounds pretty decent at 192. (I'd ballpark it at around the equivalent in some respects of a 256 kbps MP3... but there are subtle diffs that make such a comparison tricky.)

That said the results of competitive loudness squashing tend to sound awful to my ear no matter what the delivery medium is.
Old 18th November 2007
  #18
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Quote:
Originally Posted by joaquin View Post
So how does it work? What are the criteria behind the selection of Info (Data) to be disposed in favor of file size?
Thanks.
Search google for 'audio compression codecs theory' or something similar. Its a very complicated concept that involves human hearing perception - psychoacoustics.

The only easy way to explain it is that the algorithms first try to remove sounds that you aren't likely to hear anyway <- that's the theory anyway.
Old 18th November 2007
  #19
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Quote:
Originally Posted by travisbrown View Post
Disk space is less of an issue now than efficient network transmission. Still takes a while to send a 25-40mb file through the internet. If everyone as doing it, for the amount of audio that flies around the net, broadband would run at dial-up speeds.

Though, my 200gb of ripped CDs on my computer would balloon to a 1tb if they were all encoded with lossless compression, and almost 2tb with uncompressed files. That saves me about $600, so disk space does not go unconsidered.
Well, since I get into my truck and actually drive to record stores this isn't a problem. I don't download any free/illegal copies of mp3's from the internet.

I listen to wavs in iTunes. No suckification process between the CD and me!
Old 6th September 2013
  #20
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Quote:
Originally Posted by bongomania View Post
OK, this is interesting. I have always thought I heard compression of levels in every instance of lossy compressed data. Was that just my ears playing tricks on me?
I hear the same thing when I hear songs I've mixed that I then hear as MP3's at places like Reverbnation. It sounds like pumping to me.
Old 6th September 2013
  #21
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Quote:
Originally Posted by bcgood View Post
Well, since I get into my truck and actually drive to record stores this isn't a problem. I don't download any free/illegal copies of mp3's from the internet.

I listen to wavs in iTunes. No suckification process between the CD and me!
Since this thread was just exhumed, I'll just clarify that by ripped CDs I mean CDs that are in my collection that I have ripped, not downloading of ripped CDs.
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