CD kbps

[josel]

Hi all,
Just wondering what kbps do commercial/professional music CD's use. ( for exmample pop music CD's). Is it 128kbps or more?
If it is more then why? as I thought the human ears can only distinguish sound quality 128kbps or less.

Thankyou josel

[nic2k4]

The bitrate of audio CD is calculated by muliplying the sampling rate by the resolution by the number of channels:

44.1 kHz X 16 bit X 2 chan. = 1.411 kbps

The human ear can distinguish way more than the human brain can handle. That's why the technic used to figure out what frequencies to drop in MP3 (and others) is called psychoacoustics. Wiki http://en.wikipedia.org/wiki/Psychoacoustic_model

They may say 128k is CD quality, but it's bull (I'm only talking MP3 here). Compare the same recording done at 128 and 192. You'll find the 128 one is dull; the 192 recording has more ambiance, seems more alive. The harmonics in the music provide the ambiance. At lower bitrates too much gets removed.

[josel]

Hey thankyou, very interesting, did'nt realise how much science is behind the kbps.

[TJohns]

And I believe that the highest audio frequency that can be accurately recorded is equal to half the sampling frequency (44.1 KHz, => 22.05 KHz sounds), so people with better than average hearing may notice the loss of "top-end" notes. This was part of the reason DVD's went to a 48 KHz sample rate for better hi-fi reproduction.

Trev

[DesignByOnyx]

I know this is an old topic, but I just want to clarify:

44.1kHz x 16bit x 2chan. = 1411 kbps

[Noahtuck]

I know this is an old topic, but I just want to clarify:

44.1kHz x 16bit x 2chan. = 1411 kbps

So you brought up a 2 year old thread just to repeat exactly what was already stated

44.1 kHz X 16 bit X 2 chan. = 1.411 kbps

[Cornucopia]

I think he's trying to show the difference between:

1) 1411 kbps (aka 1,411)
and
2) 1.411 kbps

as the former is 1000 times more than the latter. The earlier post may have been a misprint, or it may have been bad calculation. Hard to say.

I think it is a little late, but if it helps some newbie searching through posts, so be it.

BTW, 48kHz wasn't chosen really for "higher" sampling rates, rather it was a combination of A) not basing the sampling rate on an archaic historical tech spec (as was 44.1, relating to Laserdisk and Umatic PCM bandwidths/videosampling periods when mastering) and B) giving a little more "leeway" for analog pre- and post- filtering so that the kind of filters can be simplified and not incur additional artifacts. It's easier to divide as well.

Scott

[VegasBud]

DesignByOnyx,

It's amazing how much difference a decimal point can make. If "the devil is in the details", then the decimal point must be the most demonic symbol.

Welcome to VideoHelp.

[Darius_bd]

I know this is an old topic, but I just want to clarify:

44.1kHz x 16bit x 2chan. = 1411 kbps

The original wasn't entirely wrong, as he mixed up the decimals.

It can be either

44.1kHz x 16bit x 2chan. = 1,411 kbps

or

44,1kHz x 16bit x 2chan. = 1.411 kbps

or even

44.1kHz x 16bit x 2chan. = 1'411 kbps

it's weird there isn't a global way of decimal notation.


One doubt struck me though.... if it's 1411 kbps, and a CD has 4800 seconds [80 minutes], then wouldn't a CD contain up to 6.77 gb?

[betwixt]

Now someone else has their units wrong!

The bit rate is Kilo BITS per second, not BYTES per second !

Brian.

[jman98]

Now someone else has their units wrong!

The bit rate is Kilo BITS per second, not BYTES per second !

Brian.

Um, no. NOBODY mentioned "bytes" in any of the previous posts. Do a search for the word on the page and you will see. So thanks for nothing.

If anybody has access to a time machine, can you please go back in time and stop one post wonder DesignByOnyx from posting to this thread? Thanks.

[jagabo]

Compare the same recording done at 128 and 192. You'll find the 128 one is dull; the 192 recording has more ambiance, seems more alive.

A lot will depend on which MP3 encoder you use. Some will sacrifice channel separation at lower bitrates. Others will sacrifice high frequencies. Etc.

[Darius_bd]

Now someone else has their units wrong!

The bit rate is Kilo BITS per second, not BYTES per second !

Brian.

darn, totally right Brian... I'm just good at decimal notation it seems.

*recalculating*

Uhm, yeah, now the number is saner... 837 MB. Those 137 surely used for headers, lead in, lead out and stuff.

Thanks ;]

[Noahtuck]

Now someone else has their units wrong!

The bit rate is Kilo BITS per second, not BYTES per second !

Brian.

Um, no. NOBODY mentioned "bytes" in any of the previous posts. Do a search for the word on the page and you will see. So thanks for nothing.

If anybody has access to a time machine, can you please go back in time and stop one post wonder DesignByOnyx from posting to this thread? Thanks.

Yeah, i could not believe it when i saw this thread brought up AGAIN!!!
DERR

Compare the same recording done at 128 and 192. You'll find the 128 one is dull; the 192 recording has more ambiance, seems more alive.

A lot will depend on which MP3 encoder you use. Some will sacrifice channel separation at lower bitrates. Others will sacrifice high frequencies. Etc.

Ya know what the difference is between 128 & 192 mp3's ??

Nothing because they are BOTH CRAP!!!!!!
Straight up or compared to a true lossless source.
And i don't care who or what they are encoded with, if someone can't tell the diff. just from listening to them, you either have very bad ears/mind or really crappy equipment 8)

But i have heard some pretty good mp3's but they were 192 or higher but i can still hear the diff.

Not to bash MP3's completely, because i do use the format, they do have their uses, like on a small portable player with this little earbuds, but when people want to pack a few hundred onto a disc to listen to them through any kind of decent system,

And that's directed more at the original post you quoted from 2 years ago :P

[nic2k4]

Sorry, my bad! The comma and period are so close together on the keyboard, sometimes I push the wrong one. I always proof read before posting, but it's not as good as having someone do it for you.

Still, bring back a 2 year old post ...

Yeah, MP3 sound is crap, but in the car (or any noisy environment) it's perfectly acceptable. A hell of a lot better than cassette tape anyway. And way more practical than burning CDs; my deck has USB and SD ports.

For the purist with a sound proof room and a decent setup, it's totally out of the question. I just like to listen to my music where ever I go, not just locked up in a room.

Should mention I only encode with LAME 3.96, either through EAC or BeSweet. And take a look at all the command line switches it has. Do some tweaking and don't settle for the presets, you'll notice a big improvement.

[Supreme2k]

Forty-four point one kilohertz multiplied by sixteen bits multiplied by two channels equals one thousand four hundred eleven kilobits per second

[ranosb]

Should mention I only encode with LAME 3.96, either through EAC or BeSweet. And take a look at all the command line switches it has. Do some tweaking and don't settle for the presets, you'll notice a big improvement.

I like audiograbber with Lame...

[Rejoice]

Now someone else has their units wrong!

The bit rate is Kilo BITS per second, not BYTES per second !

Brian.

darn, totally right Brian... I'm just good at decimal notation it seems.

*recalculating*

Uhm, yeah, now the number is saner... 837 MB. Those 137 surely used for headers, lead in, lead out and stuff.

Thanks ;]

Thanks guys for this wonderful post which helped me to understand how music is stored onto a normal CD.
But just thought I'd clarify the above post regarding the actual size for 80 minutes of audio burned on a CD.
When you do the math, it's actually 807.5MB instead of 837MB. You get 846,720,000 Bytes for an 80 minute disc which when converted to MB(Mega Bytes) is only 807.5MB, as 1MB=1024KB=1,048,576 Bytes.

The following link explains well how the extra 107.5MB is stored onto a Normal CD suitable for 700MB data or 80 minutes audio.
http://www.execulink.com/~impact/cd-r.htm

Cheers!
Rejoice.