MP3 question

[andybleaden]

Hmmmmm.

Interesting info from all three there, thanks

What I can never get my head around even with the amount of music that I have is this:

1 If I rip a cd track at 256 k for the pc do I need to click the VBR rate as well? Ie are they seperate?

2 What is then the difference between original cds and these when these mp3 are reconverted ( albeit from a high rate cd) ?

3 What if any difference is there in this 20 K bit remasters and the old japanese 88hz remasters.....how does this relate to the mp3 stuff?

4 Last one , honest ! If I use the default vbr ( say with min rate set at 256, does this go above 256 when needed and does it add lots of memory or is it offset with the swings and roundabout s of less demanding parts? ie are the minimal sounds done at say 192 or what ever?

answers on a post card and the winners will recieve a special mp3 track! B)

Edited June 23, 2004 by andybleaden

[couw]

1. VBR is a choice you make. It makes files smaller without losing any or much of the quality. Whether you rip at 256kbps or set 256kbps as maximum value in a VBR rip should not matter. If the algorithm that decides what bitrate it's gonna use is any good, the dense passages will be done at 256kbps and only sparse sections will be encoded at lower bitrates. In CDex go to [options] > [settings] > [encoder] and select a VBR method, you will notice that you can now also select a maximum encoding rate a bit further up. Play around a little and see how much the difference is in file size and sound quality. As noted, a good (or conservative) VBR algorithm with a certain maximum bitrate (say 256kbps) will produce results that are as good as a straight rip at that same bitrate (256kbps in our example).

2. mp3 is a method to compress the music. It is a completely different way to encode. CDs hold something similar to wav files, where each time segment has an equal size in terms of ones and zeros. Compare it to a bitmap where information on every pixel is stored separately. An mp3 would then compare to a jpg, where there is vectorisation allowing to describe bunches of pixels at once. Depending on the settings, the quality can be indiscernable to merely okay.

3. not. CDs are all 16bit in the end. the 20 (24) bit stuff refers to the remastering process. The music on 20bit CDs was remastered using files encoded using 20bits, i.e. using 2 to the power of 20 encoding values instead of 2 to the power of 16; mostly the rate at which the original analog waveform was sampled is higher too (88Hz or 96Hz instead of 44.1). The redbook standard for CDs is 16bit though, so the masters are downsampled before the music is put on the disks. The sampling rates of mp3s have little to do with these CD bits as we're talking about a different encoding system entirely.

4. you will have to select a minimum and a maximum value for your VBR. if both are set to 256, there isn't much to vary. I should say that if the VBR algorithm is good, you can make the minimum as low as 32 kbps, it would simply never be used (or only during silent passages).

[Kevin Bresnahan]

Two of my mp3 players specifically state that they cannot play back VBR files.

In the past, when I encoded using VBR, the resulting files were huge, almost as big as if I had simply encoded at 256 kbps. I'll download CDEX and experiment.

CDEX's website seems to indicate that they have developed their own LAME encoder. Does anyone know which LAME encoder MusicMatch uses? I have had great success with MusicMatch.

Later,

Kevin

[casanovas347]

I with you there too. I think the marketing expression "CD quality" has helped that misconception. Why would anyone need anything more than "CD quality"?

Let me say it like this:

if ya increse the bit-rate you have more dynamic-headroom in the music....normal 16bit rate "only" handle 96dB (theroretical value is 6dB per Bit...but thats just theoretical stuff )

it would make more sense to use 24bits/44.1khz than 16bits....but most of the music today has no dynamic in recording.... ....SACD is cool, but difficult to spread your cds, cuz most peps use the old players....

on Mp3 you loose information behind that what you hear.....it cuts all "masked" information

greeetz

Paco

[RDK]

96 dBs is more dynamic headroom than one usually experiences in real-life; it's far more than one needs for music. I think the most dynamic music only hits the 20 dB or so range...

[Brandon Burke]

Brandon, you post a lot on threads about digital audio but I think the person that doesn't understand digital technology is you.

People seem to fall back on the same old "series of snapshots" theory. If you do the math, you'll see that you can completely resurrect an analog waveform as long as you sample at a rate of 2 times the maximum frequency. You can compare the before and after using all the test gear you want but it will show you that if done right, it will be identical.

Done right is the important part of that last paragraph. Artifacts from the sampling circuits and clock can and do add noise to the decoded analog waveform. Error correction of a corrupt bitstream will also skew the results. However, it is not as if any of these artifacts will result in "jagged" analog waveforms and almost every listener would be unable to detect the difference. Experiment with a record and a CD burner. Do some blind listening tests. I would be willing to bet that nearly everyone reading this would be extremely hard pressed to determine which playback was the LP and which was the CD-R of the LP.

If you are arguing that there is audible content above 22 Khz, that's different and I am still on the fence about this. I believe that there is some signal up there but 1) I can't hear above 15 KHz (neither can most male humans) and 2) any signals up there will be so low in level as to be inconsequential. Right now, I believe most people falling back on this argument do so because the "series of snapshots" argument doesn't hold water.

Bad-sounding CDs are the result of bad mastering and/or bad digital-to-analog conversion in the player.

Later,

Kevin

You're probably right, though I'm not sure that was the most tactful way of bringing it up, Kevin.

I'm a librarian--not an engineer--and have only taken on learning the digital side of audio preservation in the past year or so. My training is in methods of housing, degradation, etc. With this in mind, you need to understand that the "snapshot" theory makes quite a bit of sense to quite a few people; as not everyone in the world is an engineer. I would appreciate more information on this topic if you can recommend something. My friend gave me a copy of Mastering Audio by Bob Katz as a going-away present the other day. He made it sound like a good guide and would often refer to it during discussions of things like dither, etc.

In any case, I was unaware that we had so many engineers on the board until this thread and look forward to learning from all of you.

Good day.

[Kevin Bresnahan]

You're probably right, though I'm not sure that was the most tactful way of bringing it up, Kevin.

I'm a librarian--not an engineer--and have only taken on learning the digital side of audio preservation in the past year or so. My training is in methods of housing, degradation, etc. With this in mind, you need to understand that the "snapshot" theory makes quite a bit of sense to quite a few people; as not everyone in the world is an engineer. I would appreciate more information on this topic if you can recommend something. My friend gave me a copy of Mastering Audio by Bob Katz as a going-away present the other day. He made it sound like a good guide and would often refer to it during discussions of things like dither, etc.

In any case, I was unaware that we had so many engineers on the board until this thread and look forward to learning from all of you.

Brandon, I'm probably taking too much out on you. Mea culpa. Unfortunately, your view of "snapshots" with regards to digital audio is very prevalent in the world of audio, particularly among analog fanatics. I just had a bit of a knee-jerk reaction.

Mind you, I like analog... however, I still think that digital audio gets a bad rap because of crappy remastering jobs. I sometimes wonder that if all the effort some of these companies put into these beautiful SACD remasters was put into remastering CDs instead, we might not even be talking about SACD or DVD-Audio.

BTW, I have a copy of Kenneth Pohlman's "The Compact Disc Handbook" that has served me well. In it, Pohlman seems to distill the theory into more understandable terms. The intro is on-line here. Pohlman's other book, "Principals of Digital Audio" is more of a textbook but might strike a chord among some of the board's more intrigued denizens.

BTW II, Nyquist's theory is the subject of many heated debates among analog and digital proponents. A technical description of his work can be found here. One more thumbnail description can be found here.

Later,

Kevin

[casanovas347]

96 dBs is more dynamic headroom than one usually experiences in real-life; it's far more than one needs for music. I think the most dynamic music only hits the 20 dB or so range...

don't set dynamic range with dynamic headroom....96dB is just a theoretical value.....most DACs in normal CD players use a dynamic range of about 90dB

most music today use a dynamic headroom of 20dB or so...absolutly right what you said.....

but the dynamic range between the little wispher to a inferno of tone (created by a acoustic instrument so as the piano...or take a whole classical orchestra...contains a dynamic range more than 100dB.....yeah, sure...you need better speakers, an amplifier who dosen't decrese the dynamic range of a "real" good DAC....a room where you can hear music, specially designed to hear music ....that would be much expensive....

...for minidisc or mp3 or AAC....we don't worry about that all!

ooh there is a cool way to decrese Audio-File (for internet-use) without loss

for Windows: http://www.softsound.com/Shorten.html

for Linux or Mac: http://www.hornig.net/shorten/

have fun!

greetz

paco

[ajf67]

Great topic. And good posts from so many of you. It's a topic I don't know nearly as much about as I would like to. Most of my knowledge comes from reading magazines like The Absolute Sound and Stereophile and things like that. Like Brandon, as a non-engineer, I have found the snapshot analogy makes sense.

That's an interesting test that Kevin brings up though on a/b-ing an LP and a CD-R. I have made quite a few CD-Rs for friends of my LPs but I have never done an a/b on those. All the a/b comparisons I've done are between LPs and commercially-issued CDs. I almost always hear a difference betwen those, although I don't know how much is mastering vs the qualities inherent in each of the media.

Brandon mentioned Masterning Audio by Bob Katz. Any other good books on the mastering process out there, or any thoughts on that one? I'll check out the Nyquist and Pohlman links too.

[Daniel A]

Whether you rip at 256kbps or set 256kbps as maximum value in a VBR rip should not matter.

I'm not sure about this. From what I've heard, it's not a good idea to limit the bitrate when using VBR. In most situations it would be OK, but I think that the results under some conditions could be worse than a constant bitrate if an especially difficult passage occurs, where the algorithm wants a higher bitrate. If file size is an issue, I think it would be better to adjust the VBR options for heavier compressing (= lower resulting bitrate), or even using ABR, which lets you preset the average bitrate.

[andybleaden]

1. VBR is a choice you make. It makes files smaller without losing any or much of the quality. Whether you rip at 256kbps or set 256kbps as maximum value in a VBR rip should not matter. If the algorithm that decides what bitrate it's gonna use is any good, the dense passages will be done at 256kbps and only sparse sections will be encoded at lower bitrates. In CDex go to [options] > [settings] > [encoder] and select a VBR method, you will notice that you can now also select a maximum encoding rate a bit further up. Play around a little and see how much the difference is in file size and sound quality. As noted, a good (or conservative) VBR algorithm with a certain maximum bitrate (say 256kbps) will produce results that are as good as a straight rip at that same bitrate (256kbps in our example).

2. mp3 is a method to compress the music. It is a completely different way to encode. CDs hold something similar to wav files, where each time segment has an equal size in terms of ones and zeros. Compare it to a bitmap where information on every pixel is stored separately. An mp3 would then compare to a jpg, where there is vectorisation allowing to describe bunches of pixels at once. Depending on the settings, the quality can be indiscernable to merely okay.

3. not. CDs are all 16bit in the end. the 20 (24) bit stuff refers to the remastering process. The music on 20bit CDs was remastered using files encoded using 20bits, i.e. using 2 to the power of 20 encoding values instead of 2 to the power of 16; mostly the rate at which the original analog waveform was sampled is higher too (88Hz or 96Hz instead of 44.1). The redbook standard for CDs is 16bit though, so the masters are downsampled before the music is put on the disks. The sampling rates of mp3s have little to do with these CD bits as we're talking about a different encoding system entirely.

4. you will have to select a minimum and a maximum value for your VBR. if both are set to 256, there isn't much to vary. I should say that if the VBR algorithm is good, you can make the minimum as low as 32 kbps, it would simply never be used (or only during silent passages).

Well I have to say a big thanks for the help and the information you have provided for me here. I must say it has helped me a great deal to understand the issues both on this post and the one about cdrs over ....there>>>

It is clear to me that there are certain things now I must do to my cd ex programme and test it a little more. Many thanks again matey for your help and advice on this.

This is once again a good example of what the board is good for.

By the way I have just sent you an email too!

BTW 2 Just gotta shout it out for the latest track I have got a hold of which is the Randy Weston Little Niles set from the Mosaic Select

[Saxophone__Vagina]

Alright, there are many things i want to responde to in this thread.

First, the analogy for mp3s going around is not quite right, mp3s cut out the frequencies that we cannot hear, where as a wav file records and stores information for everything.

Second on the quality of mp3s, You will think mp3s sound bad if you only have downloaded badly encoded copies of album from p2p programs. The best mp3 encoderer set up around town is Exact Audio Copy with the plugin LAME. It rips CDs really well. www.hydrogenaudio.org has a lot of info

Also, there is an article that states when buring a CD, the audio quality is somewhat restored/fixed. I cannot for the life of me find it right now, but i read it. The amount that is fixed is minor, but it does happen some how.

I think that is all i wanted to address.

[Claude]

No, nothing is restored.

If an MP3 is played on the PC, it is being decoded. If it is converted to wav for audio CD burning, it is being decoded in the same way.

It could be that the article meant that, when creating an audio CD from MP3s and playing it on a dedicated CD player, it sounds better because the player is better than the sound card of the PC when playing MP3s directly. But that has nothing to do with the wav file being better than the source mp3 file.

[couw]

Also, there is an article that states when buring a CD, the audio quality is somewhat restored/fixed. I cannot for the life of me find it right now, but i read it. The amount that is fixed is minor, but it does happen some how.

many CDr burners have error correction, just like a normal CD player has. This means that if you succeed to burn a copy protected disk, the build-in mistakes will be gone. A CDr copy of a copy protected disk is likely to run on a car stereo. Same goes for scratches etc. My own Joe Henderson - Inner Urge CD will not play on my machine, it get's stuck somewhere. I burnt a CDr and no more skipping. Of course this all depends on your CDr drive and on your machine.

[Kevin Bresnahan]

The best mp3 encoderer set up around town is Exact Audio Copy with the plugin LAME. It rips CDs really well. www.hydrogenaudio.org has a lot of info

Correct me if I'm wrong, but the copy of Exact Audio Copy that I downloaded has no LAME plug in. I had to go and find one. The trouble I had was that everyone thinks their LAME encoder is the best. Some use trade names since LAME is open code. Also, several of the websites wanted $$ to download their version. I still have never been able to get a clear answer as to which LAME-style encoder is the "best".

I have also read that Musicmatch uses one of the best mp3 encoders out there. I use MM almost exclusively to rip my mp3s and I think they sound pretty good. Is it straight LAME 3.96 or a home-grown version? I don't know.

Later,

Kevin

[neveronfriday]

Anyone else here that prefers formats such as MPC? I haven't ripped anything to MP3 (for myself) in ages. MPC is my format, comes close to lossless quality, albeit creating bigger file sizes. With decent speakers, MPC is the format of my dreams (was introduced to it by some German freaks about a year or two ago).

Cheers!

[neveronfriday]

Mind you, I like analog... however, I still think that digital audio gets a bad rap because of crappy remastering jobs. I sometimes wonder that if all the effort some of these companies put into these beautiful SACD remasters was put into remastering CDs instead, we might not even be talking about SACD or DVD-Audio.

Yes. Yes. Yes!

Thanks for that one, Kevin.

It can't be repeated often enough!

Cheers!

[Claude]

The problem with alternative (mostly better) compression formats is that many portable players don't support them. MP3 is the common standard that all players support. At higher bitrates (192kbs and above) it is also very good, at least for portable use.

[Saxophone__Vagina]

The best mp3 encoderer set up around town is Exact Audio Copy with the plugin LAME. It rips CDs really well. www.hydrogenaudio.org has a lot of info

Correct me if I'm wrong, but the copy of Exact Audio Copy that I downloaded has no LAME plug in. I had to go and find one. The trouble I had was that everyone thinks their LAME encoder is the best. Some use trade names since LAME is open code. Also, several of the websites wanted $$ to download their version. I still have never been able to get a clear answer as to which LAME-style encoder is the "best".

I have also read that Musicmatch uses one of the best mp3 encoders out there. I use MM almost exclusively to rip my mp3s and I think they sound pretty good. Is it straight LAME 3.96 or a home-grown version? I don't know.

Later,

Kevin

you can download LAME Version 3.90.3, which is suppoesd to be the recommended version.

http://www.hydrogenaudio.org/index.php?act=ST&f=15&t=478&

And if you are not quite sure how to set up EAC, check out this faq, which will cover eerything:

http://home.satx.rr.com/thisdude23/eac/

make sure you follow everything correctly to get your CDs properly ripped, if you have any problems setting it up, pm me and i can help.