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Topic: How do i find out the sound quality of a CD? (Read 19740 times) previous topic - next topic
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How do i find out the sound quality of a CD?

I need to know the sample rate (in KHz) and bit depth of each and every track of an audio CD. Some (or ALL) of the tracks sound more like 22/8 than 16/44 to me. In fact, although the CD has 78 minutes of music, it seems like some of them were just upconverted to 16/44, which only increases the size, NOT the quality of the sound, right? How can i figure this out? Is there a program that will tell me?

Thanks in advance.

How do i find out the sound quality of a CD?

Reply #1 –
Audio CDs are always 44.1khz/16bit. To find out if a track might have been upsampled, you can take a look at its frequency spectrum (e.g. with Audacity). If it ends quite abruptly at around 11khz, then it could have been upsampled from 22khz.

How do i find out the sound quality of a CD?

Reply #2 –
Everything on an audio CD has to be 44.1/16.
I never heard of upsampled contents, but to identify them a spectral analysis should be enough: if there is no content above 11 kHz, it might be 22.05 kHz upsampled to CD  standard.

Do you have any example? And did you ever listen to 22/8?

Edit: MedO was faster 

How do i find out the sound quality of a CD?

Reply #3 –
Quote from: seskanda on
I need to know the sample rate (in KHz) and bit depth of each and every track of an audio CD. Some (or ALL) of the tracks sound more like 22/8 than 16/44 to me. In fact, although the CD has 78 minutes of music, it seems like some of them were just upconverted to 16/44, which only increases the size, NOT the quality of the sound, right? How can i figure this out? Is there a program that will tell me?

Thanks in advance.


Hi seskanda. Is this an original (pressed) CD or is it a copy? I've seen many instances where people burn audio CD's from low quality compressed audio (most commonly wma) even when they have the original CD at hand. It's sad but true that they just don't know any better.

How do i find out the sound quality of a CD?

Reply #4 –
Quote
...upconverted to 16/44, which only increases the size, NOT the quality of the sound, right?
Right!

How do i find out the sound quality of a CD?

Reply #5 –
You can tell the difference between pressed CDs and user-burned audio CDs by normally looking at the bottom of the discs.  Most pressed CDs are silver on the bottom with user burned CDs ranging in all sorts of colors from black, blue, green, etc.  Additionally, you can simply look at the spectral analysis of the files.  Lowpass filters will show up as frequency caps.  So an audio CD should go all the way up to 22.05 (GoldWav may show it as 22.1) KHz per channel (44.1 KHz overall).  Seeing a frequency cap, a flat line across the frequency spectrum, at something below 22.05 (20KHz, 16KHz, etc.) means that your audio CD came from lossy files (mp3, WMA, AAC, etc.).  Keep in mind that many audio CDs out there have sections of songs below 22.05 KHz but a lowpass filter will show up as a flat line across the entire spectrum.

Just where did you get your CDs from that you need to question them?

How do i find out the sound quality of a CD?

Reply #6 –
My audio CD is the soundtrack from The Shining movie. I have sound forge 7, it has spectral analysis and sonogram.

The spectral analysis shows the following for ALL of Track 1: 

Can anyone make sense of this for me? It looks like most of the frequencies are mid-range, no? There's a steady decrease in the highs, though; what does that mean?

Here's a pic of the sonogram, it shows, more or less, the same thing:

Why did everybody say it "might" by upconverted from 22/8 if the spectral analysis shows nothing after 11KHz? I've heard 22/8 before, it sounds muffled and just plain BAD. As for "pressed" CD i have NO idea, where, exactly, do i look at the bottom of CD? On the surface? Towards the edge/corners? Or is it the circular ring in the middle??

How do i find out the sound quality of a CD?

Reply #7 –
Looks like 44.1kHz audio to me.  What made you think it would be sourced from 22/8 content?  There are a thousand better reasons for crappy audio quality on CDs.

How do i find out the sound quality of a CD?

Reply #8 –
From the analysis, I see a lowpass at about 15-16kHz. Maybe this CD is burned from lossy files. AFAIK, properly mastered 44.1kHz file should have frequencies up to 22kHz, though the content in that range may not be significant.

How do i find out the sound quality of a CD?

Reply #9 –
Quote from: seskanda on
As for "pressed" CD i have NO idea, where, exactly, do i look at the bottom of CD? On the surface? Towards the edge/corners? Or is it the circular ring in the middle??


I mean is it an original CD (pressed in a factory) or is it a burnt copy (like a bootleg or something a friend or something copied for you)? Surely you know something about the origins of this disc.

BTW. It looks like it came from lossy to me. Since it's a soundtrack I guess it's possible that it was bootlegged from the mpeg2 audio of a DVD. Or it's it's really bad it then maybe even bootlegged from an mpeg capture of a video.

How do i find out the sound quality of a CD?

Reply #10 –
Quote from: uart on
Quote from: seskanda on

As for "pressed" CD i have NO idea, where, exactly, do i look at the bottom of CD? On the surface? Towards the edge/corners? Or is it the circular ring in the middle??


I mean is it an original CD (pressed in a factory) or is it a burnt copy (like a bootleg or something a friend or something copied for you)? Surely you know something about the origins of this disc.


I'd like to know this too. AFAIK, this soundtrack was never released on CD -- or else I've been looking in all the wrong places. After years of looking, I finally found a vinyl copy in Rochester around 1997 and digitized it myself.

So I'd really love to know where this CD comes from!

How do i find out the sound quality of a CD?

Reply #11 –
Quote from: seskanda on
As for "pressed" CD i have NO idea, where, exactly, do i look at the bottom of CD? On the surface? Towards the edge/corners? Or is it the circular ring in the middle??


As previously stated, pressed CDs mean that they are made in a factory where the audio content is "pressed" to the disc.  Just look on the bottom of the CD, it isn't that hard.  Pressed CDs are almost always just silver on the bottom while user burned CDs come in all sorts of different colors.  Just look on the bottom and tell us what color it is.

Your frequency plot makes it look like your CD did come from lossy files.  The lowpass appears to be at around 15KHz.  Your soundtrack might come from someone who digitized the cassette/vinyl release, encoded from a TV broadcast, encoded from the DVD/VHS release, or from many other sources.  Audio CDs go all the way up to 22.05 (22,050 in your software) for each channel.  The amount of information up at that frequency level is often lacking but it is still there.

Tell us the color of the bottom of the CD will help out a lot.

How do i find out the sound quality of a CD?

Reply #12 –
Those two graphs indeed help a lot more to understand this CD.

First, as already pointed out, the frequency cut is not at 11Khz. It seems to be around 15Khz.

Next, is this soundtrack quiet? The graphs suggest that it does, but they also suggest that the CD goes as low as -150dB (there's noise in that graph above 15Khz), so that info may be erroneous.

The file does *NOT* directly come from a lossy source. The noise over 15Khz would not be there. That shows either post-processing or analog recording. (Ok, this is debatable, but that would mean a lossy-to-lossy transcode before burning to CD)

Since other users have suggested that this CD may have never been released as CD, the possibilities of this coming from an analog recording are feasible.

Thus, the cutoff frequency could conceveably be from the medium it was recorded in, in the first place. See that the first graph shows a peak around the cutoff frequency, which could indicate an analog filtering.

I wouldn't say the quality is degraded necesarily in this recording, I don't see much content above 7Khz, but it doesn't seem there should be, in the first place.
The straight line in first graph between 7Khz and 10Khz could indicate a filter being used, probably to reduce the background noise, But at the same time, the second graph, the lower channel has a clear hit that is not softened on those frequencies, so that point would not hold true.

In the end: CD audio, the format has only one quality. But that format allows you to record a tune out of your mobile phone's speaker if you want. (of course, with no quality gain).

How do i find out the sound quality of a CD?

Reply #13 –
Quote from: kornchild2002 on
So an audio CD should go all the way up to 22.05 KHz per channel (44.1 KHz overall).

What? 

The connection between 44.1 kHz and 22.05 kHz is the Nyquist theorem, not the fact that you have two channels.

How do i find out the sound quality of a CD?

Reply #14 –
Yes but frequency plots still go up to 22.05KHz per channel as we have already observed.  I am not trying to bring up complex theories here,  just trying to explain that a frequency plot for each channel will go up to 22.05KHz for an audio CD and that they are (overall) mastered at 16/44.1.

How do i find out the sound quality of a CD?

Reply #15 –
Quote from: kornchild2002 on
Yes but frequency plots still go up to 22.05KHz per channel as we have already observed.  I am not trying to bring up complex theories here,  just trying to explain that a frequency plot for each channel will go up to 22.05KHz for an audio CD and that they are (overall) mastered at 16/44.1.



How do you figure?  I could arbitrarily set any lowpass filter I want before I master something for CD.  For instance, it is not all that uncommon to have "pop" recordings lowpassed at either 16kHz or 20kHz.
"You can fight without ever winning, but never win without a fight."  Neil Peart  'Resist'

How do i find out the sound quality of a CD?

Reply #16 –
How did we spot the lowpass filter at 15 KHz? Is it the dip i see at that point in the 1st graph?

Quote
Surely you know something about the origins of this disc.


All i know is that it was put together by www.RogersBasement.com.


Quote
Tell us the color of the bottom of the CD will help out a lot.


I googled about a pressed CD vs. a CD-R, basically anything "burned" with a CD writer is NOT pressed. So, i'm NOT sure if the color really matters.... Anyways, would you mind posting a link to a picture of a NON-pressed and a pressed CD? I'm having a hard time visualizing the difference.



So, let's recap, 3 people think the track is from a lossy file, while 1 person says NO. If it's lossy, what's the quality? Given that it most likely came from an analog source (be it vinyl or cassette), could it still be lossy? If that's the case, the only way i know that's possible is if the digitized version was saved in .mp3,, .wma or other lossy format, right?
BTW, is VHS analog? If so, what is the sound quality on it? Overall, Track 1, being the 'Main Title', is sort of quiet. Since the music is an analog synth playing a low, bass motif, that would explain a lack of highs, although there are other high frequency tones throughout the piece, which account for any highs present. Why does the line between 7-10 KHz go down for? Does the filter amount change during that time? What is a 'lossy-to-lossy transcode'?

How do i find out the sound quality of a CD?

Reply #17 –
Quote from: dreamliner77 on
How do you figure?  I could arbitrarily set any lowpass filter I want before I master something for CD.  For instance, it is not all that uncommon to have "pop" recordings lowpassed at either 16kHz or 20kHz.


That is true but the majority of the time, content that contains a lowpass filter comes from a lossy source or something that was poorly recorded.  I have yet to see a song (in my library which consists of metal) have a lowpass throughout the entire thing.  I have seen songs with certain sections with lowpass filters at 16KHz but they always go back up to the normal level.  I have two pop songs in my whole library that came from soundtracks.  They have many sections that fill up the entire 22.05KHz.  So the majority of the time yes, CDs have information up to (or around) 22.05KHz and it is a safe assumption that something with a lowpass of around 15KHz came from a lossy source.  The question of "is this CD from lossy or lossless files" gets asked ad nauseum here on the boards and everyone asks for frequency plots.  They see lowpass filters and say that the CD was made from lossy files.  The thread then disappears and no one adds further replies.  I don't see what the big deal is in assuming that the source for this audio CD is either a bad recording or came from lossy files as this is done all the time here on the boards.

Quote from: seskanda on
I googled about a pressed CD vs. a CD-R, basically anything "burned" with a CD writer is NOT pressed. So, i'm NOT sure if the color really matters.... Anyways, would you mind posting a link to a picture of a NON-pressed and a pressed CD? I'm having a hard time visualizing the difference.


I don't see what me posting pictures of CDs has to do with you simply looking on the bottom of it and telling us the color but OK.  Go to this link to see what the bottom of a pressed CD looks like.  It is the CD at the very bottom and you can clearly see that it is silver.  Here is an example of the bottom of a CD-R disc, it has a green tinge.  Here is another example of the bottom of a CD-R disc, it has a gold tinge.

Basically you should see that a pressed CD is SILVER on the bottom while CD-R discs are all other colors.  Other CD-R colors include (but are not limited to) purple, orange, blue, pink, dark green, yellow, and black.  You could always scan the bottom of your CD-R and post it if you are having difficulties flipping the disc over and examining it yourself.  Additionally, you can tell us where you purchased this CD.  So post a scan/close picture (in proper lighting) if you really want to know the answer.

Edit: the color will tell us quite a bit.  A pressed CD will be silver.  This means that the CD is an official released and was mass produced.  A CD with a different colored bottom means that it was burned with computer, it was not professionally created.  A CD with a different colored bottom could very well mean that someone took the mp3 files on their computer and simply burned an audio CD.  A pressed CD means that the studio in charge of the masters made the disc, the packaging, and was in charge of distribution.  A pressed CD is a lot less likely to be entirely from lossy files.  Modern artists tend to use mp3 sample files with their music but their entire tracks aren't lossy.  As previously pointed out, I guess many pop artists apply a lowpass filter to their master tracks.  Still, telling us the color of the bottom of the disc (or simply scanning it and posting it, you can use an image hosting website such as imageshack.us) will help narrow things down quite a bit.

How do i find out the sound quality of a CD?

Reply #18 –
Quote from: seskanda on
BTW, is VHS analog? If so, what is the sound quality on it?

Yes, VHS is analog. Analog means that the information is a response of current or voltage obtained without steps, which the medium can record more or less faithfully (This implies that analog recording is not perfect per se).
Digital is a sampled representation (so, stepped and recorded with a defined period between samples)

I can't tell about the quality of VHS. I belive it is similar to that of cassetes, but I don't know more.

Quote from: seskanda on
Why does the line between 7-10 KHz go down for? Does the filter amount change during that time? What is a 'lossy-to-lossy transcode'?


Since that is the representation of the whole song, it could be that the hits on the last part are not representative enough for the graph to change (much), and thus, the decreasing in frequency would come from the instrument itself.

a lossy-to-lossy transcode is when you have a lossy file (say mp3) and you convert it to another lossy format (mp3, wma, mp4/aac ...). I said it could be possible (not that it is), because the first lossy could do the first filtering, while the  second would not filter and add the noise distortion. I don't think this is the case. It is just a possibility.

How do i find out the sound quality of a CD?

Reply #19 –
Back in the day the HiFi stereo VHS players were touted as delivering quality comparable to a CD.

There is not enough evidence to conclude that the recording is lossy either directly or indirectly.  I'm inclined to agree with [JAZ], but I'm not familiar with Sound Forge.  If you used Audition and zoomed the window down to a fraction of a second centered at a place in the audio where there is a hard transition, I'd have a better idea.

Identifying lossy by low pass alone is a very crude method.

How do i find out the sound quality of a CD?

Reply #20 –
Quote from: kornchild2002 on
A pressed CD will be silver.  This means that the CD is an official released and was mass produced.


There are pressed CD's with gold undersides and CDR's with silver undersides. But if you want to know whether a disc is a CDR or not, just pop it in a PC and check the ATIP information with software like this.

How do i find out the sound quality of a CD?

Reply #21 –
I have looked at the website and found this: (the emphasis is mine)

Quote
All CD's are either out of print, extremely hard (or impossible) to get, or never made at all! The extra music and dialogue tracks are recorded off of that film's Digital Laser Disc or DVD. Audio is Crystal Clear on these babies!


I guess that's why some track's quality are different. Recording from Laser Disc or DVD involves many steps, all of which is lossy and can affect audio quality if not done properly.

Anyhow, I still cannot figure it out why low-pass is there, can it be that the creator of this disc "mix" with the audio even further? I guess you can only know if you ask him.

How do i find out the sound quality of a CD?

Reply #22 –
Quote from: varoot on
Recording from Laser Disc or DVD involves many steps, all of which is lossy and can affect audio quality if not done properly.


Obtaining one of the audio tracks from a DVD-V is actually a pretty simple process if you know what you are doing. There is freeware readily available on the web for the purpose.  An example of appropriate software would be MPEG Streamclip.

How do i find out the sound quality of a CD?

Reply #23 –
A lot of steps are required to deliver music to a CD and many of them aren't 100% reversible, but we don't typically call CDs lossy.

Anyhow, I think people are specifically talking about lossy compression.

How do i find out the sound quality of a CD?

Reply #24 –
I own a pressed CD that I purchased from Asia that was sourced from a lossy scene release. Just because a CD is pressed does not mean it cannot be lossy!