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Author Topic: The Distortion of Sound  (Read 7908 times)

Paul G. OBrien

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Re: The Distortion of Sound
« Reply #10 on: August 26, 2014, 07:28:58 PM »

Incorrect.  All MP3 codecs create frequency response changes and loss of dynamic range (lower bit depth) capability.  The reduction in bit depth may not be noticed depending upon the actual source but the frequency response shift is noticeable on all but the worst systems or earbuds/headphones. 


Reduction in bit depth is irrelevant consider how much dynamic range current popular recording use, and I hear(nor see with Adobe Audition) any difference in freq response between a CD and an MP3 conversion done at 320kb/s or higher.
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Lee Buckalew

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Re: The Distortion of Sound
« Reply #11 on: August 26, 2014, 08:01:33 PM »



Reduction in bit depth is irrelevant consider how much dynamic range current popular recording use, and I hear(nor see with Adobe Audition) any difference in freq response between a CD and an MP3 conversion done at 320kb/s or higher.

Notice that I said the reduction in bit depth may not be noticed depending upon the original.  It is most definitely noticeable on some recordings.  It is very easy to hear the shift of MP3 in music that has response below 40Hz or so and to hear the shift in balance as long as you are using reasonable accurate equipment.

Lee
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Paul G. OBrien

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Re: The Distortion of Sound
« Reply #12 on: August 26, 2014, 09:08:04 PM »

It is very easy to hear the shift of MP3 in music that has response below 40Hz or so and to hear the shift in balance as long as you are using reasonable accurate equipment.

In a double blind test? Look, my argument here is not that there isn't some degradation in sound with compressed music formats, it's that the video totally overstates how much MP3 formats are to blame for the bad sound people are being exposed to. Yes there are all kinds of really bad MP3 files floating around in cyber space, but if a completely computer illiterate were to make an MP3 copy from a current top100 artist's CD with the default setting in windows media player(for example), that copy would be indistinguishable from the original on your average home audio system or portable listening device. The reason I'm confident in making that statement is because the recording on that CD is already far more compromised than it would have been even 10yrs ago and nowhere close to being hi-fi.. IMO. The big problem with todays music is not with portable music formats it's a lot further back up the food chain in a place where the consumer and probably the artists have no control over.
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Tommy Peel

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Re: The Distortion of Sound
« Reply #13 on: August 26, 2014, 09:24:23 PM »

Here's a thought that might make for some interesting discussion. One of the things iTunes promotes are "Mastered for iTunes" versions of songs/albums. It sounds as if the tracks with that label are mastered with the intention to put them in the iTunes file format(256 kbps AAC). Any thoughts on this? Are there things that can be done in the mastering process to make a track Mastered for iTunes better than one ripped from the CD into the same format? I've never done a A-B comparison of these tracks with "normal" CD versions, but I'd be interested to see the difference.

Sent from my Moto X (XT1053) using Tapatalk

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Lee Buckalew

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Re: The Distortion of Sound
« Reply #14 on: August 26, 2014, 10:22:08 PM »

Here's a thought that might make for some interesting discussion. One of the things iTunes promotes are "Mastered for iTunes" versions of songs/albums. It sounds as if the tracks with that label are mastered with the intention to put them in the iTunes file format(256 kbps AAC). Any thoughts on this? Are there things that can be done in the mastering process to make a track Mastered for iTunes better than one ripped from the CD into the same format? I've never done a A-B comparison of these tracks with "normal" CD versions, but I'd be interested to see the difference.

Sent from my Moto X (XT1053) using Tapatalk

This is absolutely necessary if you want the same mix.  Each codec actually requires a different mix in order to have the same blend of parts.  Our classical musicians have asked this to be done whenever there are multiple download formats available or if a mix is available on CD but also on a compressed download.

Lee
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Lee Buckalew
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Lee Buckalew

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Re: The Distortion of Sound
« Reply #15 on: August 26, 2014, 10:39:51 PM »

In a double blind test? Look, my argument here is not that there isn't some degradation in sound with compressed music formats, it's that the video totally overstates how much MP3 formats are to blame for the bad sound people are being exposed to. Yes there are all kinds of really bad MP3 files floating around in cyber space, but if a completely computer illiterate were to make an MP3 copy from a current top100 artist's CD with the default setting in windows media player(for example), that copy would be indistinguishable from the original on your average home audio system or portable listening device. The reason I'm confident in making that statement is because the recording on that CD is already far more compromised than it would have been even 10yrs ago and nowhere close to being hi-fi.. IMO. The big problem with todays music is not with portable music formats it's a lot further back up the food chain in a place where the consumer and probably the artists have no control over.

Arguing that because current pop production techniques often mix/master to the lowest common denominator of is not the point here.  If I do have a poorly produced pop tune that has limited frequency response and limited dynamic range, and that's all I ever listen to, then your argument would make sense.  If however I listen to music that has good frequency response from 20Hz or below up to the highest that I can still hear (17kHz or so) and I also care that the mix translates (I may or may not) then the distortions matter.  Aside from the frequency response limitations there is significant artifacting created.  This is easily heard by taking a CDA and ripping it into a good phase coherent DAW as two track BWAV and ripping the same CDA in as an MP3 to the same session.  Now polarity invert the left and right track of either the BWAV or the MP3.  What you now hear is the difference between the data compressed tracks and the uncompressed tracks.  It is worse at lower rates but even a 320kbps MP3 creates significant amounts of artifacting and I can hear it not only double blind but on tracks that I have never heard before.  I can, more than 90% of the time, tell you if I am hearing an MP3 even on a cheaper system with no reference comparison.  With a reference in AB, nearly 100% of the time.

Unless I am never going to use an image except as a thumbnail I don't take a picture at low resolution, I take it at as high a resolution as I practically can.  Then, when I want to use it in a situation where low resolution is preferred, I convert a copy.  The same thing goes with digital audio formats for me.all of my files are at CD quality minimum.  If I need to down convert something for a particular device or other need I can but my main files are all full resolution.

There is a large difference between, there is no (noticeable) difference and in certain situations or with certain base material those differences don't matter.

Lee
« Last Edit: August 26, 2014, 10:43:31 PM by Lee Buckalew »
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Keith Broughton

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Re: The Distortion of Sound
« Reply #16 on: August 27, 2014, 06:32:24 AM »

it's that the video totally overstates how much MP3 formats are to blame for the bad sound people are being exposed to.
I have to agree with you on that point. They do not distinguish the difference betweem low and high bit rate.
As for the listening "demo" it was all BS for sure.
My hope is that even if a bit poorly "proven"  the basic point of the idea that we need to listen to better sound will be taken.
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Paul G. OBrien

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Re: The Distortion of Sound
« Reply #17 on: August 30, 2014, 07:18:45 PM »

Arguing that because current pop production techniques often mix/master to the lowest common denominator is not the point here.

But it is the point, at least it's the point I'm trying to make. The fact that the source material that the general public listens to is of such poor quality completely negates any negative impact MP3 conversion may have on it, and means that the conclusions stated in the video are totally misdirected.
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Luke Geis

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Re: The Distortion of Sound
« Reply #18 on: August 31, 2014, 01:42:10 AM »

Here is the basic run down. Anything with 44.1khz and above is totally transparent as far as our ears can tell. Which means that anything below that bit depth will have degraded quality that can be heard. The way music is compressed and decompressed is another story. You are no longer looking at bit depth, you are looking at the amount of key data that will be re-constructed later. The codec takes the data and " decides " what is valuable or not and then rebuilds the information back into something that resembles the original. If the information is missing and or scarce, the codec will create aliasing effects that we can hear. 128kbps is considered to be the lowest compression that is " acceptable " to most people. For many 320kbps is the only option if one must go to MP3. I am one such person who believes that 320kbps is the floor that we should aim for. Any lower and it is not truly good enough.

The way the music is produced can have a huge impact on the way the codec compresses. The codec has an algorithm that " looks " for information within a certain range and threshold. Anything not in that range or threshold is eliminated. When the codec rebuilds the information, those missing pieces are made up to fill in the blanks. Songs that are really loud and " not " dynamic are consistently outside of the codec threshold and will tend to sound overly compressed and crunchy. The codec negates important parts of the music that when put back together reduces dynamic range and it clips the peaks in order to " fit " within it's criteria.

Bad dithering is another huge contributor to bad MP3 exchanges. There are several dithering options and not all are created equal. Anytime you change the songs bit depth, you are introducing noise and aliasing artifacts. If these songs are then tuned into MP3 the bad information is made even worse as the codec further reduces it's lack of information.

Streaming music is hard. Imagine streaming fully uncompressed data for hours on end. A regular CD in wave format is around the ballpark of 70-80 min worth of music. Each minute of music is roughly 10mb, with a full cd capable of safely holding about 737mb of data with error correction. That would work out to several gigs a day if you listen to music regularly on your phone. The current data streaming for pandora is 192kbps if you choose that rate and have a premium account. I am lucky to have been grandfathered into truly unlimited data usage because I listen to a lot of pandora at the highest available speed. My emailing and other data usage done on my phone nearly places me as a data abuser!!!!! I have used 3.07gigs in this billing cycle and I still have another week to go. Over 1/3rd of that is Pandora!!!! I'm not usually over 5 gigs, which is the current cap for most carriers. Point being that with full data transfer of music that is streamed would add up very quickly. That being said, I can hear aliasing even with 192kbps.

The reason most people are happy with MP3 even in it's lowest form is because who doesn't want 128 songs on a CD, or 500 songs on a 2 gig ipod? It's nice to have the numbers even if the quality is low. I myself have 162 gigs worth of high end MP3 music and that is about 30,000 files!!!!  Those same files in wave would take 10X the amount of space to hold. More recent codecs are better at compressing music and maintaining space. 20 years ago HDD space was small and so the compression also had to be aggressive. Now a 500+gb HDD costs very little and space is not an issue. I could get most almost all of my music in wave format on a single drive these days if I wanted! Within the next five years we will see full data streaming capability for sure! 44.1khz CD quality music streamed hot right to your computer or phone! Europe is starting to do it already! MP3 compression of music will be a thing of the past soon!

The next thing that will improve music will not be elimination of the compressed data, but the elimination of compression period....... The mastering process where music is squeezed into the lifeless, dynamic-less loud music that it has become, will hopefully be dropped to a level where the music sounds the way it does as it comes off the channel tracks and onto the master track. If you have ever heard a song before and after mastering you are usually amazed! The un-mastered song is quieter and sounds bigger, dynamic and open. The current standard of mastering does as much damage as the MP3 compression. Mastered music is compressed ( highly ) and has a bit of it's sonic content reduced, sometimes drastically. It is true that music that is louder gets attention easier, but if everyone is doing it, then no one wins. We need to change the game from loudest and most produced, to simply best produced.
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Jonathan Goodall

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Re: The Distortion of Sound
« Reply #19 on: August 31, 2014, 01:46:14 AM »

But it is the point, at least it's the point I'm trying to make. The fact that the source material that the general public listens to is of such poor quality completely negates any negative impact MP3 conversion may have on it, and means that the conclusions stated in the video are totally misdirected.

So would you agree with, Poor source material + MP3 (or what ever) conversion + rubbish speakers/head phones = Totally unacceptable  :)
« Last Edit: August 31, 2014, 01:51:47 AM by Jonathan Goodall »
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Re: The Distortion of Sound
« Reply #19 on: August 31, 2014, 01:46:14 AM »


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