Head-Fi.org › Forums › Equipment Forums › Sound Science › Are CD's compressed?
New Posts  All Forums:Forum Nav:

Are CD's compressed?

post #1 of 78
Thread Starter 

This might be a noob question for someone with so many posts...but yeah. a friend asked me..i was baffled for a second. From what i curently know. CD's hold 700MB. the files on it are usually in this RAW format. Are the songs in the RAW format have a specific bit rate? AIFF has a standard bit rate of 1411kbps. is this the same as in RAW? I know some albums have a lot more songs on one disk than others? explain the whole process please :)

post #2 of 78

CD audio has a bitrate of 1411.2kbps = 44.1k sample size * 16 bit depth * 2 channels

 

 

Since a CD is the source recording, it is inherently uncompressed.  There is no lossy algorithm used which would delete or alter information, and there is no lossless algorithm used which would use tricky math in order to shrink the file with patterns for later reconstruction.

 

 

Some CDs have more songs than others, because the producers wanted to put more or fewer songs on the album :P  The format allows a maximum total of 80 minutes of music, and a maximum of 99 tracks.  Any combination of tracks that comes to less than 80 total minutes can be used. 

 

 

Feel free to ask any followup questions you may have :) 

 

 

 


Edited by El_Doug - 12/16/11 at 8:24pm
post #3 of 78
Thread Starter 
Quote:
Originally Posted by El_Doug View Post

CD audio has a bitrate of 1411.2kbps = 44.1k sample size * 16 bit depth * 2 channels

 

 

Since a CD is the source recording, it is inherently uncompressed.  There is no lossy algorithm used which would delete or alter information, and there is no lossless algorithm used which would use tricky math in order to shrink the file with patterns for later reconstruction. 

 

 

Feel free to ask any followup questions you may have :) 

thank you :)

i'll seperate my questions with the ---------

 

Now on to itunes vs Exact Audio Copy vs dbpoweramp

 

So is there really a big difference between all of them from what i hear. EAC will not have any errors. and so if you hear any crackles or artifacts in your lossless music. it means there was some error and you should go back and do it through EAC? so should i be using EAC from now on instead of itunes-->ALAC?

-----------------------------------------------------------------------------------------

Clipping/over excursions

This is when you either hear a crackle,pop or metalic sound right due to not enough amp power in and the loudness war right? 

 

One of my songs "Iridescent" by linkin park has this problem. it sounds like it might just be a bad error. When the majority of background music cuts out and it's just the soloist signing. you can hear little fuzzy artificat cracks tricle across the high vocals. 

This is probably due to the bad ripping right? I downloaded from two different downloads, both had same problem. they could just be using teh same main download source though.

 

Ok just tested Shadow of the Day by Linkin Park. on my 2010 macbook pro. it had no problems playing with no cracks and anything. i used the macbook pro for the top song too. however, when i plug my headphones into my ipod and play the same FLAC song back. i hear many driver made cracks and pops. is this due to clipping and or overexcursing from not enough power? This happens with a couple songs

 

I heard pops in some of my songs. some say it's do to clipping or overexersion from
 

24bit? all the songs i hear the cracks and pops from are from my linkin park minutes to midnights album. all in FLAC but in 24bit. could 24bit and 48KHz be doing this on my ipod? I remember reading that 24bit is just an increased dynamic range. and i know what sampling rate is. on the ipod. can it automatically switch to 24bit and 48KHz or does it just stay 16bit @ 44.1KHz the whole time? if it does. could this be causing the problem..unlikely right. i didn't change my MAcbook's setting to outpu in 24bit and 48KHz. i do that on my PC. but my PC's DAC is not nearly as good as the Cirrus Logic and whatever amp in my macbook pro.

 

could it be a combo of 24bit, 48KHz that isnt' supported on the ipod, added in with the pretty big 1666kbps ALAC and not enough power on the ipod?

------------------------------------------------------------

ALAC/FLAC decoding?
ok so what i think happens is this. you endode a song into ALAC or FLAC. and when you play it back on your music player. it decodes it. and uncompresses the compressed FLAC or ALAC file. which would then result in larger bit rate ...is this correct.? so..like. you take the current bit rate you see. find the compression rate in the properties menu. and do some math. and you can calculate bit rate that way right? 

 

Wait just had an epithamy....the maximum bit rate no matter what for 16 bit songs (majority ) is 1141kbps while for 24bit is 2304kbps... right?

Thank you very much for you and anyone that can answer these questions...i don't know if these are advanced questions, i've been on head fi for a while. but sound science has really been my low knowledge base


Edited by bowei006 - 12/16/11 at 8:50pm
post #4 of 78
Quote:
Originally Posted by bowei006 View Post

thank you :)

i'll seperate my questions with the ---------

 

Now on to itunes vs Exact Audio Copy vs dbpoweramp

 

So is there really a big difference between all of them from what i hear. EAC will not have any errors. and so if you hear any crackles or artifacts in your lossless music. it means there was some error and you should go back and do it through EAC? so should i be using EAC from now on instead of itunes-->ALAC?

-----------------------------------------------------------------------------------------

Clipping/over excursions

This is when you either hear a crackle,pop or metalic sound right due to not enough amp power in and the loudness war right? 

 

One of my songs "Iridescent" by linkin park has this problem. it sounds like it might just be a bad error. When the majority of background music cuts out and it's just the soloist signing. you can hear little fuzzy artificat cracks tricle across the high vocals. 

This is probably due to the bad ripping right? I downloaded from two different downloads, both had same problem. they could just be using teh same main download source though.

 

Ok just tested Shadow of the Day by Linkin Park. on my 2010 macbook pro. it had no problems playing with no cracks and anything. i used the macbook pro for the top song too. however, when i plug my headphones into my ipod and play the same FLAC song back. i hear many driver made cracks and pops. is this due to clipping and or overexcursing from not enough power? This happens with a couple songs

 

I heard pops in some of my songs. some say it's do to clipping or overexersion from
 

24bit? all the songs i hear the cracks and pops from are from my linkin park minutes to midnights album. all in FLAC but in 24bit. could 24bit and 48KHz be doing this on my ipod? I remember reading that 24bit is just an increased dynamic range. and i know what sampling rate is. on the ipod. can it automatically switch to 24bit and 48KHz or does it just stay 16bit @ 44.1KHz the whole time? if it does. could this be causing the problem..unlikely right. i didn't change my MAcbook's setting to outpu in 24bit and 48KHz. i do that on my PC. but my PC's DAC is not nearly as good as the Cirrus Logic and whatever amp in my macbook pro.

 

could it be a combo of 24bit, 48KHz that isnt' supported on the ipod, added in with the pretty big 1666kbps ALAC and not enough power on the ipod?

------------------------------------------------------------

ALAC/FLAC decoding?
ok so what i think happens is this. you endode a song into ALAC or FLAC. and when you play it back on your music player. it decodes it. and uncompresses the compressed FLAC or ALAC file. which would then result in larger bit rate ...is this correct.? 

Thank you very much for you and anyone that can answer these questions...i don't know if these are advanced questions, i've been on head fi for a while. but sound science has really been my low knowledge base


Doesn't really matter what you rip with, as long as it has no errors. Just make sure error checking is on and try to rerip if it's bad. EAC can use AccurateRip to verify that a file is accurate, and it has powerful error correction features, but you're not likely to run into an error on scratchless CDs (some exceptions).

 

There's two kinds of clipping. Clipping from the Loudness War is the result of increasing the gain of the digital files past the limit of the bit depth (96 dB for CDs and 16 bit files). You aren't going to be able to solve this by reripping, because it's baked into the mastering. You can only hope to find another pressing of the CD. Clipping from an amp is similar, but happens because the amp doesn't have enough voltage swing to form the peaks of the analog signal, causing it to plateau. You can lower the volume to solve this. Clipping can also be introduced on your end of the digital stream by increasing gain with stuff like MP3Gain or equalizers. Always lower frequencies with an equalizer, don't raise them. iPod equalizers don't make sure to keep peaks at 0 dBFS, so they can clip. Are you using an EQ setting on yours?

 

What is the source of your 24 bit files? Did it come from a normal CD? There's no point encoding it as a 24 bit file if it didn't come from a 24 bit source. Likewise no point encoding it at 48 kHz if it's a 44.1 kHz source. Was this a high resolution download from somewhere?

 

ALAC and FLAC, during playback, is decompressed to the original WAV, accurate bit for bit. All lossless compression works like this.

post #5 of 78
Thread Starter 
Quote:
Originally Posted by Head Injury View Post

 You can lower the volume to solve this. Clipping can also be introduced on your end of the digital stream by increasing gain with stuff like MP3Gain or equalizers. Always lower frequencies with an equalizer, don't raise them. iPod equalizers don't make sure to keep peaks at 0 dBFS, so they can clip. Are you using an EQ setting on yours?

 

What is the source of your 24 bit files? Did it come from a normal CD? There's no point encoding it as a 24 bit file if it didn't come from a 24 bit source. Likewise no point encoding it at 48 kHz if it's a 44.1 kHz source. Was this a high resolution download from somewhere?

 

ALAC and FLAC, during playback, is decompressed to the original WAV, accurate bit for bit. All lossless compression works like this.


I don't use an EQ with anything. so my original deductions on what were happening was correct :)

the description for the 24bit files were "The highest quality version of Linkin Park's 2007 album Minutes To Midnight. The master which all released versions would have been converted from."

I'm also skepticale of how they/he/she got this supposed master

so...during playback. it decompresses into 1411.2kbps for 16bit files? and 2304kbps for 24bit (i re edited my thing while you were replying it seems)

 

And yes, as a personal scale. how were my questions? too nooby? I just want to know where i about fall on teh sound science level,to better help other deciding junior head fiers


Edited by bowei006 - 12/16/11 at 9:00pm
post #6 of 78

Just thought I'd point out that because of Red Book requirements the data rate on a CD is substantially higher than 1.4mbits/sec. That figure only accounts for the audio data, not the extra bits needed for various methods of error correction. So compared to the standard CD format, even a WAV is compressed, in the sense that it uses fewer bits than the original.

 

edit: and I'd be very skeptical of any claim of a quality Linkin Park album


Edited by anetode - 12/16/11 at 9:02pm
post #7 of 78
Thread Starter 
Quote:
Originally Posted by anetode View Post

Just thought I'd point out that because of Red Book requirements the data rate on a CD is substantially higher than 1.4mbits/sec. That figure only accounts for the audio data, not the extra bits needed for various methods of error correction. So compared to the standard CD format, even a WAV is compressed, in the sense that it uses fewer bits than the original.

 

edit: and I'd be very skeptical of any claim of a quality Linkin Park album



I was extremely skeptical. master!? the songs had a lot of background hiss. not extremely much, but a good amount. and.........some song names were wrong. instead of "Waiting for the End" it was "Waithing for the End" :/

 

and so...when uncompressed and playing on media plyers like ipods. 16bit audio files will play at about 1.4mbits/second right?

post #8 of 78

 

Linkin Park in 24 bit?

 

Either it's the studio master, or someone ripped it from vinyl, or someone doesn't know what they're doing and upsampled it to 24 bit lol.

 

 

Upsampling 16/44.1 to 24/192 and creating huge files is pointless, when there are algorithms that can do that on the fly.

 

By the way, use ASIO or Kernel Streaming if you have 24 bit content, as DirectStream has some issues, I think it plays it back at 16 bit or something.

 

 

In my opinion the difference is so faint it's better to use upsampling algorithms, but when we have 30TB external harddrives that will change and more 24/192 studio masters will be released.

 

I know Head Injury is skeptical there is any difference between 16 and 24 or from DAC to DAC and it's just "plotting 16 bits and connecting the dots to make a wave" but I think the truth is that making that wave is much harder than it intuitively seems, our equipment sucks at waves. =p

post #9 of 78
Quote:
Originally Posted by bowei006 View Post

I don't use an EQ with anything. so my original deductions on what were happening was correct :)


Why jump to the conclusion you were correct? How high do you have the volume turned on your iPod?

 

Bit rate depends on channels, bit depth, and sampling rate. Use the formula El_Doug posted.

 

I'd welcome evidence of that truth of yours, kiteki, you know I would.

post #10 of 78
Thread Starter 
Quote:
Originally Posted by kiteki View Post

 

Linkin Park in 24 bit?

 

Either it's the studio master, or someone ripped it from vinyl, or someone doesn't know what they're doing and upsampled it to 24 bit lol.

 

 

Upsampling 16/44.1 to 24/192 and creating huge files is pointless, when there are algorithms that can do that on the fly.

 

By the way, use ASIO or Kernel Streaming if you have 24 bit content, as DirectStream has some issues, I think it plays it back at 16 bit or something.

 

 

In my opinion the difference is so faint it's better to use upsampling algorithms, but when we have 30TB external harddrives that will change and more 24/192 studio masters will be released.

 

I know Head Injury is skeptical there is any difference between 16 and 24 or from DAC to DAC and it's just "plotting 16 bits and connecting the dots to make a wave" but I think the truth is that making that wave is much harder than it intuitively seems, our equipment sucks at waves. =p


It seems my skepticality has been confirmed....... there is close to no way that some guy magically got a hold of a studio master as claimed. back a while ago i thought that my headphones would pop on that song because of the super high bit rate...guess it was just the amp voltage :/ (invest in an ZO2, ibasso, or E11 :) ) 

and so.... i guess im still a noob in sound sciience :(

thank you all :)

post #11 of 78

Not sure if skepticality is a word, but it sounds cool.

 

skeptical fatality?

 

 

It's probably a vinyl rip, I'd call that a skepticality.  Try finding Belezza Crudel Vivaldi stuff.

 

post #12 of 78
Thread Starter 
Quote:
Originally Posted by kiteki View Post

Not sure if skepticality is a word, but it sounds cool.

 

skeptical fatality?

 

 

It's probably a vinyl rip, I'd call that a skepticality.  Try finding Belezza Crudel Vivaldi stuff.

 



minutes to midnight...an 2007 album in vinyl?

wait nvm
http://www.amazon.com/Minutes-Midnight-Vinyl-Linkin-Park/dp/B000PITXPU
o
k..i guess it is probably legit then. probably now explains the little crackles i hear during that part of iridescent


Edited by bowei006 - 12/16/11 at 9:43pm
post #13 of 78

Cool.

 

You need a 24/192 DAC or sound-card to play it though.

 

post #14 of 78

First, lossy compression is entirely different from lossless compression.

 

CDs are compressed if you're talking about master files in the studio. They are not if you're talking about everything else.

 

Some albums have more songs than others? That's because a CD is limited to a certain time duration and songs have various lengths. All CDs have the same theoretical sound quality, but quality varies due to differences in recording, mixing, mastering, converting, etc.

post #15 of 78
Thread Starter 
Quote:
Originally Posted by kiteki View Post

Cool.

 

You need a 24/192 DAC or sound-card to play it though.

 



This is my audio codec in my main desktop

http://www.via.com.tw/en/products/audio/codecs/vt1708/

it supports it..but it's not great. might be the amp. when listening straight out of teh back panel. there is no lows at all.. no low frequency.like...legit. it says there is a headphone amp.............. idk but i have to plug it into my desktop speakers audiio out to get decent sound

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Sound Science
Head-Fi.org › Forums › Equipment Forums › Sound Science › Are CD's compressed?