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SteveG
Location: United Kingdom
Posts: 6695
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 Posted - Fri Jun 15, 2001 6:41 am
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There have been several recent debates in this forum about the merits or otherwise of different lengths of CD, and different types of CD writing, sometimes misleadingly called ‘burning’. For the benefit of those people not in possession of some of the basic information, I thought I’d fill in one or two of the gaps in an attempt to clarify one or two things. Hopefully there is more light than heat, but I have added a few comments, and with Graeme and Beetle around… But it’s quite long, I’ll warn you now.
It’s a new topic, because I’m getting fed up with scrolling down an unrelated one to add even more unrelated comments. So…
The original CD audio standard was the famous ‘red book’ standard published jointly by Sony and Philips back in the mists of time. The important thing to note about it, is that it contains the basic standards to which audio must adhere in order to be recorded at all, and is the fundamental standard on which all the others are based. It specifies details about the Table of Contents (TOC), and the coding and interleave requirements for robust digital recording, and the notorious 74 min. limit. It even allows for 20Mbytes of other digital data to be recorded, but I’ll ignore that here. And it says Disk At Once (DAO) writing, but it would – it was the spec for mass-produced commercial CDs.
The interleave stuff is quite significant, though, especially in the context of ‘clicks’. Audio data is arranged into interleaving ‘frames’ when it’s written to a CD. This interleaved data from the CD is decoded in firmware when the datastream is reconstructed, and as not all firmware is identical, it rather follows that some players are going to be more susceptible to problems caused by incorrect frame boundary data than others. Most decent CD writing software fills the last frame with trailing zeros, ensuring a correct boundary, but it ain’t always so. It follows that even using DAO with weird numbers in frames can produce clicks, especially if those weird numbers are CE cue data, not audio.
But if we continue, the confusion starts to set in. I want to make something very clear from the outset. The CD writer in your PC writes CD-R disks. The standard for these is contained within the Orange book standard, Pt.ll. This standard was added in 1988, and basically allowed multi-media and multi-session CD’s, which by implication means TAO (Track At Once). This is the basis on which EasyCD creator, Nero, etc, etc. include the option to do it – it’s in the standard.
Now, before anyone gets too excited, let me remind you of what I said earlier – the red book standard is the basic audio one, and has not been superseded, as far as I’m aware. So if you are going to make an audio CD that has any chance of passing muster as the basis of a glass master, ideally it should conform to the rather conservative red book spec if you want to guarantee that it will play on all non-faulty players. The reason that the red book length spec. hasn’t been increased is that there are still a lot of dodgy players around, and not all of them are portables. A lot of the problems stem from the inability of their laser head servos to track accurately beyond the 74 minute boundary – I have one that consistently won’t play anything beyond 75 mins. If you want to do audio on an Orange Book CD writer, you still have to abide by the red book standard, or run some risks, and here’s another one:
CD-Rs reflect significantly less laser energy back from the disk than commercially duplicated audio CDs. The very best ones can manage 75-80%, I believe, but CD-RWs are much worse, with figures around 20%! The immediate result of this is that the servo has even more trouble coping, as it relies on the reflected beam to track the spiral, and the actual pit reading is an extremely hit and miss affair. So although it’s easily possible to burn 80mins onto a CD, and even Philips have done it, (naughty, naughty) you should be aware that there is a significant difference between a highly reflective commercial CD and your CD-R. Combine all of these factors… well, I won’t do 80mins on a CD-R, anyway.
The real difficulty, though, is that the Orange book standard was changed to allow for 80min disks in 1996. Here’s a quote from TDK:
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…The first manufacturer to offer extended-capacity CD-R discs, TDK has been supplying recording studios with 80-minute CD-R discs for music mastering applications since 1996. The company's decision to bring its extended-capacity technology to the wider business and consumer markets follows on the publication earlier this spring of updated industry standards (Orange Book Part II) for 80-minute discs.
The new CDR-80 (multimedia) and CD-TWIN-R80 (home music) discs differ chiefly from 74-minute discs in the pitch (fineness) of the data track inscribed on the disc. Since data recorded on a CD-R follows a single, spiral track from the center to the perimeter of the disc, a finer track pitch allows more data to be written on the disc. The finer track pitch, however, may make the new 80-minute discs incompatible with some recorders and players. In addition, because some computer recording software does not support 80-minute / 700 MB CD-R, users may have to update their software accordingly or contact the software manufacturer to establish compatibility. - TDK |
But it’s not even that simple – check out (for a start)
http://www.mscience.com/faq57.html
Hence the confusion. It makes realistic sense, though, that all specifications have to take account of the lowest common denominator if they are going to have any meaning at all. But if you want to burn non-standard CDs, that’s fine, as long as you are aware of the implications. You can drive your car fast if you like, but please forgive me for pointing out why the wheels might fall off.
This isn’t all there is to it by a long way, but it’s probably the most relevant stuff. If you think this much is bad, just be grateful that I haven’t told you about what really happens to audio data on a CD. You probably would be surprised…
Steve
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PapillonIrl
Posts: 158
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Posted - Fri Jun 15, 2001 6:59 am
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C'mon man...you've got me all interested now ! What really happens ?
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dkten
Posts: 45
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Posted - Fri Jun 15, 2001 7:15 am
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Steve,
I was going to start another thread (at my peril) asking about the difference between track-at-once and disk-at-once, but first did a search and found your thread.
Thanks for the informative post. I found it most enlightening (although I probably fall closer to the second group in your quote below.)
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The people I feel slightly sorry for are not those like you and me, Robert, who can quite happily make sense (or not)
of it, but the poor sods who ask the questions and must wonder what on earth they've walked into! |
doug
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BVDD
Posts: 48
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Posted - Fri Jun 15, 2001 7:25 am
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Good stuff, Steve!
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SteveG
Location: United Kingdom
Posts: 6695
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Posted - Fri Jun 15, 2001 8:10 am
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C'mon man...you've got me all interested now ! What really happens ?
-PapillonIrl |
You really, really want to know?
I’m not so sure that you will…
First, all the data is multiplexed into one stream by alternating all the 16-bit data words. By definition, the first word is a ‘left’ word – the rest follows. Then the data is interleaved by doing a serial to 8-bit stream parallel conversion, and feeding each bit stream through its own different delay, and re-serialising. I’m not going to bother with a detailed explanation of how that works – it’s complicated. Now an extra 8-bit word, the sub-code data, is inserted before each block of audio. The control words enable the data to be ‘rebuilt’ in the player. The data field can later be rebuilt 98 control words at a time. The control word is where things like SCMS data are stored, but that’s by the way. Next comes a process called 8 to 14 modulation. This is where the 16-bit data words are changed into two 8-bit data words, and each one is changed into a 14bit ‘symbol’. The term ‘symbol’ is used to differentiate between 16-bit and 14-bit words. A ‘symbol’ is really a 14-bit word, but that’s confusing… Lastly, 3 ‘coupling’ bits are written between each symbol. Then the error correction code is added. The last thing written is a unique 24-bit sync word which identifies the start point for the frame.
So, a data frame has a sync word, a control word, 12 symbols of data, 4 symbols of error correction, 12 more symbols of data and four more symbols of error correction. That takes up 588 bits, as there are 3-bit gaps between each section.
All of this is done because of the problems of writing pit data onto a CD. Pits come in 9 different sizes, varying from 0.833 micrometres to 3.56 micrometres long, and 0.5 micrometres wide. - these are the outside tolerances. On a normal CD there is a track spacing of 1.6 micrometres nominally. I’m absolutely not going to explain about pit sub-harmonics and the clock frequency. That really would be going too far!
But the conclusions are as follows: All the guff talked by ‘Audiophiles’ about this is based pretty much on total ignorance. You can either reconstruct this totally mangled mess, or you can’t. But it was done this way because, believe it or not, you pretty much can. After the re-clocking and reprocessing the data back into a stream, the D/A converters and what comes immediately afterwards are the only things that will significantly affect the audio quality. The reconstructed clock is crystal-controlled, which might just affect the output timing slightly, I suppose. The error correction has three main checking methods, parity, interleave error checking, and linear interpolation. If there is agreement, you will get the output (this is a bit of an over-simplification, but it will do for now).
Are you still sure you wanted to know?
Steve
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younglove
Posts: 314
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Posted - Fri Jun 15, 2001 10:17 am
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Does the red book standard say anything about
the track pitch? Are 80-minute discs not
red-book compliant regardless of how much is
recorded on them?
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Graeme
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Posted - Fri Jun 15, 2001 11:32 am
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Thank you SteveG for your concise explanation of an extremely complicated subject.
I had thought of posting something similar myself, but decided that it might be thought a bit OTT and certainly too technical by some. However, it is a complex subject which could do with some airing. If only people realised just how complex this system is, then they might be a little less inclined to play around with it.
I thought the Orange Book quote re the pitch of the data track was interesting - this one had slipped by me since I am mostly concerned with burning (yeah, I know it's a misnomer, but I can't see how we can change that now) discs to Red Book standard. As you are obviously aware, it was (presumably, is still, with certain brands) quite possible to overburn a 'standard' 74 min disc, long before 80 min discs were on the market. The data track pitch of these discs remains the same, of course, you are merely using spare 'real estate' on the disc as supplied.
Your later missive re EFM and CIRC should also have been an eye-opener to many people as well. The one bit of information which you didn't give - and which I think might surprise a lot of people - is that, after all the extra bits have been added to make the system work, the actual bit rate of a CD is slightly in excess of 4.3MB/s. It never ceases to amaze me just how such a complicated bit of technology can be made available to the general public for so little cost.
However, the one thing which I personally was happy to see was this statement;
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| But if you want to burn non-standard CDs, that’s fine, as long as you are aware of the implications. |
... which is exactly what I have been saying all along.
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beetle
Location: USA
Posts: 2591
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Posted - Fri Jun 15, 2001 12:09 pm
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I knew all of this, guys. I did my homework a long time ago.
FWIW, I don't and cannot burn 80 min. blanks past 78 min. Besides, most of my projects don't exceed 50 minutes, not that this makes a difference.
Time will tell whether these discs will last.
I'm getting bored with this subject anyway.
Edited by - beetle on 06/15/2001 2:03:56 PM
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SteveG
Location: United Kingdom
Posts: 6695
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Posted - Fri Jun 15, 2001 1:43 pm
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Does the red book standard say anything about
the track pitch? Are 80-minute discs not
red-book compliant regardless of how much is
recorded on them? -younglove |
Now this is an intelligent question. I think it goes something like this:
The Red book actually mentions two track pitch standards, one for 63min disks and one for 74min ones. There is some conjecture about how 74mins was actually arrived at - the best story is about some Beethoven Symphony or whatever... Anyway, enough of that.
The Orange book standard, now revised, says that you can legally store 700MBytes of data on a disk. Not only that, but the ATIP at the beginning of the disk, which is precoded with the spiral length, will confirm this to your writer. Since Orange book disks can legally contain audio, this has been interpreted by many as meaning that you can legitimately store 80mins of audio on it, and I can't actually prove that that's wrong. But you have no right to expect this to play on an audio-only CD player, for two reasons:
Firstly, the reflectivity of your CD-R may not be high enough. And the pitch dimensions of your disk do not conform to either of the Red book standards! So in a strict interpretation, then NO CD-R with an 80 minute blank in it can ever make a Red book CD that fully conforms to the standard. You should use 74min blanks, and pray about the reflectivity.
I wasn't going to mention the pit clock rate, and how it's recovered, but Graeme's sort of goaded me into it. I did say earlier that there were 9 different pit sizes written onto the disk, and obviously the pit rate will relate to the 4.3218 Mhz clock for the data rate. Since the clock cannot be directly recorded onto the CD, it has to be extracted from elsewhere to reform the data. The pit lengths were actually chosen so that when the CD is spun at a constant linear velocity, the combined effect of reading them continuously will be to generate sub-harmonics of the recording clock rate, which can then be reconstituted into the 'proper' clock by a Phase-Locked-Loop (PLL) system.
It's actually a very clever system, because it can also take account of small speed variations, and average out the spindle drive speed to provide an overall correct replay rate.
You may have noticed that most fast CD-ROM drives appear to read audio in a 'burst' mode. They actually read a lot of data into a buffer, read it out slowly, and only increment the drive when they need to. This is why, if you can actually read all of the data off a disk, the transport isn't as critical as the audiophiles would have you believe.
I suppose Graeme's going to try and get me going about single and three-beam readers and groove wobble next. I shall try to resist the temptation. But you should be aware that there's more...
But just for a laugh, get a load of this; If a CD pit was the size of a grain of rice, your CD would be half a mile across!
Steve
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beetle
Location: USA
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Posted - Fri Jun 15, 2001 2:08 pm
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And let's not even start with the jitter fiasco and how it relates to audiophilles!
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Jim Records
Posts: 32
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Posted - Fri Jun 15, 2001 2:11 pm
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I was told on this forum that anyone who has the older version of Adaptec DirectCd Ver.3.01d, that you can not use it because it is for text,like installing a pdf .Document on a cd-rom read disc,etc.,& this will work for that operation only.
They told me I have to buy their new version called:Easy Cd Creator Ver.5.
This is the software that will transfer my old LP records,& make Wave files on my hard drive.
I was also told when you click on the wave file,using Easy Cd Creator it will automatically make the wave file from the empty Cd-R disc burn to disc.
So is that correct?
So I bought at Best Buy yesterday this software, & I hope this will finally get me on my way, burning to cd\r disc.
I had a 50 pck. cd\r from Memorex.Only have now 18 left now.
I have a 10 pk. cd\rw from Memorex = 650 mb. 74 min.When I get started, I will buy another CD-R full pack of 100 disc's.
I allready have:1: Recording one side of a LP record.
2:And I have NOW, 6 tracks that were installed. Play back: No faults seen or heard.
I WAS ready to make it into a wave file, BUT it failed.
The Cd-R disc was damaged,so it was ruined.
I asked Beetle,& he told me you have the wrong program,& suggested I buy the latest Ver. of Easy CD Creator 5, & this will do the job.
If any one has any further advice, please inform me if the above statements are true.
Thank You. Jim Records.
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beetle
Location: USA
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Posted - Fri Jun 15, 2001 2:32 pm
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| I asked Beetle,& he told me you have the wrong program,& suggested I buy the latest Ver. of Easy CD Creator 5, & this will do the job. |
I don't recall having stated that, and I did a search to see where and or if could have stated that in error. I did not find anything of the sort! You may have the wrong person. If you find it. point it out to me and I will see exactly what it does say. However, CD Creator 5 should, from what I've been reading, convert your mp3's and burn then to your CD-R as wave files on the fly. You can certainly record them as data. I did state several times on this board and others that I use Cool Edit 2000 for all of my mp3 conversion as doing it yourself is the best way to go. I have also stated that I use CD Creator 4 for strictly burning wave files to CD-R, and that CD Creator is an overbloated monstrosity.
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If any one has any further advice, please inform me if the above statements are true.
Thank You. Jim Records. |
I hope you are not trying to blame your misunderstanding of this stuff on me!
Edited by - beetle on 06/15/2001 2:34:12 PM
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Graeme
Member
Location: Spain
Posts: 4663
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Posted - Fri Jun 15, 2001 2:41 pm
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| I was told on this forum that anyone who has the older version of Adaptec DirectCd Ver.3.01d, that you can not use it because it is for text,like installing a pdf .Document on a cd-rom read disc,etc.,& this will work for that operation only. |
DirectCD is 'packet writing' software - and not very good at that, either, in my opinion. Without going into details, it allows you to use a CD-RW as a sort of slow disk drive. It is totally unsuitable for Audio.
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They told me I have to buy their new version called:Easy Cd Creator Ver.5.
This is the software that will transfer my old LP records,& make Wave files on my hard drive. |
Although I haven't used Adaptec EZCD since v4.00, this is essentially true.
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I was also told when you click on the wave file,using Easy Cd Creator it will automatically make the wave file from the empty Cd-R disc burn to disc.
So is that correct? |
Not even sure if I understood that last bit - "automatically make the wave file from the empty Cd-R disc burn to disc". If you mean clicking on the .wav file on your hard disc to transfer it to the CD-R, then the concept makes more sense. But, not being an EZCD user, I can't confirm that statement. Plenty of users here though, so I expect someone else will follow this one up.
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| I asked Beetle,& he told me you have the wrong program,& suggested I buy the latest Ver. of Easy CD Creator 5, & this will do the job. |
Now I am really confused, I thought you said this was the version you had bought anyway?
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| If any one has any further advice |
Plenty of that around here :-)
If you had not aleady bought EZCD, I would have recommended something else. However, it's too late to change that now, so let's just consider a few other things.
Turn off all background tasking on your commputer by clicking Cntrl+Alt*del and closing any application you do not actually need to burn discs. Especially, disable any screensaver you might have running and turn off Windows Task Manager (it's a real memory and interrupt hog).
Do not try and do other things while the CD is burning. You might get away with it, depending on a lot of variables, but trying to multitask at the same time as burning puts a real strain on a computer system and seriously shortens the odds for a failure.
Always use branded discs if you seek reliability, both in terms of quality and longevity.
Unless there are some really compelling reasons for so doing, do not use CD-RW discs for audio. You seriously limit the probability of playback on other machines (see above in this thread).
I'm sure someone can add a few more things to the list, but this should start you off.
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SteveG
Location: United Kingdom
Posts: 6695
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Posted - Fri Jun 15, 2001 2:41 pm
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| I was told on this forum that anyone who has the older version of Adaptec DirectCd Ver.3.01d, that you can not use it because it is for text, like installing a pdf Document on a cd-rom read disc,etc.,& this will work for that operation only. They told me I have to buy their new version called: Easy Cd Creator Ver.5. This is the software that will transfer my old LP records,& make Wave files on my hard drive. I was also told when you click on the wave file, using Easy Cd Creator it will automatically make the wave file from the empty Cd-R disc burn to disc. So is that correct? -Jim Records |
There have been reports of problems with EasyCD Creator 5.0 running under Win2K. But as far as I know, it will do what you want if you are using Win98 or ME. Beetle says it's bloatware - I don't know about 5.0 but 4.03 certainly qualifies!
Steve
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Graeme
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Location: Spain
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Posted - Fri Jun 15, 2001 2:45 pm
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| Graeme's sort of goaded me into it. |
Moi! Goad? - not I :-)
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| It's actually a very clever system ... |
This has to be the understatement of the year :-).
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| I suppose Graeme's going to try and get me going about single and three-beam readers and groove wobble next. I shall try to resist the temptation. But you should be aware that there's more... |
Ooh!! What a teaser!
Go on, give it to them straight.
;-)
Edited by - graeme on 06/15/2001 2:46:08 PM
Edited by - graeme on 06/15/2001 2:46:56 PM
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SteveG
Location: United Kingdom
Posts: 6695
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Posted - Fri Jun 15, 2001 3:51 pm
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I need some sleep, so you'll have to wait, Graeme. Beetle nearly got it right about the jitter, but there are actually two types of it, and information about the critical, (i.e. not audiophile) one can make a significant difference to CD-ripping, so I'll do that tomorrow sometime.
I just realised that I put the names Graeme and Beetle right next to each other. I hope they don't squabble...
Steve
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beetle
Location: USA
Posts: 2591
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Posted - Fri Jun 15, 2001 5:10 pm
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Heh-heh!
I think our friend Jim is confused over which app in CD Creator to use for music. The package contains a lot of applications, one of them being using your CD-R's like a floppy. There is Spin Doctor which allows you to copy your CD's vinyl and tapes to the hard drive. I do NOT recommend it for anything, really.
It has a bunch of stuff for restoring your hard drive, making photo slides, making video CD's, ect...THAT's why I call it bloated, "bloatware"!. It also has a totally useless audio editor.
What do you say, Graeme, another round?
Edited by - beetle on 06/15/2001 5:13:24 PM
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bragov
Location: USA
Posts: 88
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Posted - Fri Jun 15, 2001 8:39 pm
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Steve, you said:
First, all the data is multiplexed into one stream by alternating all the 16-bit data words. By definition, the first word is a ‘left’ word – the rest follows. Then the data is interleaved by doing a serial to 8-bit stream parallel conversion, and feeding each bit stream through its own different delay, and re-serialising. I’m not going to bother with a detailed explanation of how that works – it’s complicated.
Is that final? I'm interested.
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beetle
Location: USA
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Posted - Fri Jun 15, 2001 11:00 pm
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It may do well for anyone interested to pick up Ken C. Pohlman's book...ah shoot! I forgot the title and I can't find the book, but it is an excellent text book on all you want to know about digital audio.
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seanbaker
Posts: 228
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Posted - Sat Jun 16, 2001 1:50 am
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So...? To insure a good glass master in the worst situation..... I'd be safe using 74 minute CD-Rs and write in DAO mode? Anything else?
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SteveG
Location: United Kingdom
Posts: 6695
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Posted - Sat Jun 16, 2001 4:57 am
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Steve, you said:
First, all the data is multiplexed into one stream by alternating all the 16-bit data words. By definition, the first word is a ‘left’ word – the rest follows. Then the data is interleaved by doing a serial to 8-bit stream parallel conversion, and feeding each bit stream through its own different delay, and re-serialising. I’m not going to bother with a detailed explanation of how that works – it’s complicated.
Is that final? I'm interested. -bragov |
How can I resist Vicky's plaintive cry?
You really need pictures for an easy explanation of how it's actually done. What is more useful is knowing why it's done. It's all to do with not putting all of your eggs in one basket. If your audio is broken up into little bits and spread around on the disk, damage, which only usually occurs in one place stands a good chance of being repairable by the cross-interleaved Reed-Solomon error correcting mechanisms. By using this 'temporal spreading', which becomes 'spatial spreading' on the disk, in conjunction with the error correction means that quite large holes in the data can be patched around in the replay system. This very neatly brings me on to:
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| So...? To insure a good glass master in the worst situation..... I'd be safe using 74 minute CD-Rs and write in DAO mode? Anything else?-seanbaker |
If you use the right CD-writing software (Graeme can help you here), then those are probably the most important items, yes. But you should be aware of one or two other problems. Firstly, it's important to make sure that the post-data gap is correct. This has to be 2 secs (150 sectors)long, with null data in it, and all '1's in the subcode 'P' channel, although most software will do this automatically.
The thing that can stuff you, though, is checking your disk for errors on a CD-ROM that handles CIRC by automatically correcting the 'E32-unreadable' errors. It is very easy to miss things this way which will make it through to the glass master and be reproduced on all of your production CDs, so it's always worth checking all of your stuff on a crappy, old, audio CD player before you send it off to be mass-produced.
There are all sorts of other requirements as well, but these are common to all written CDs, so they won't be an issue. It's worth remembering to check things like the SCMS status, though, if you don't want mass digital duplication of your stuff to be immediately possible. Personally, I think that this is so easily overcome anyway that it's hardly worth having.
Most mastering houses have fixed their LBRs (Laser Beam Recorders), that are actually used to make the glass master, so that they won't abort for every little thing. But this usually involves an extensive checking process, and it's always better to have avoided the mistakes in the first place.
Graeme may well have stuff to add to this...
I'm really not going to tell you every single little thing - if you are that interested, there's a lot of information on the web, and several excellent books about it. Check out John Wilkinson on digital audio in general - he's pretty good.
The CD spiral track is wobbled by about 2 percent at 22.05kHz (I think), and this is all part of the servo process used to keep the laser tracking the spiral. Philips/Marantz players use single-beam pickup systems, along with Denon, Sentra and plenty of others, and most of the far east use 3-beam systems. Don't get confused, though. There's still only one laser in all of them, it's just about the way that the beam is handled by the optics. My personal view is that there's not much difference between them when they're set up correctly, but that this is easier to achieve with the single-beam ones.
The jitter will be a separate post.
Steve
Edited by - SteveG on 06/16/2001 05:54:19 AM
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SteveG
Location: United Kingdom
Posts: 6695
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Posted - Sat Jun 16, 2001 6:52 am
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Are all CD rippers equal? Do they all work as well with different drives?
One of the problems with the original Red book specification is that nowhere does it specify that addressing has to be block-accurate. So what happens with most CD drives is that the data from the CD is fed into a FIFO buffer, but the data’s block address is handled separately – it’s pulled out of the sub-code handler part, and shoved off to a different part of the drive’s circuitry at the same time that the block is read.
This is all well and fine for one block, but the problem comes when the drive has to get the next block. If the drive has stopped in order to wait for the Hard Disk to store the extracted data, the chances of it hitting exactly the right block when it starts again for the next read are diminished somewhat. It’s usually a pretty small error, but it can, in bad cases, sound like tiny stutters on the extracted audio, or omitted bits. The best fixes for this are actually in software, but it’s worth noting that most Plextor drives have actually addressed the hardware problem, and tied the block addresses to the relevant audio. The software fix works by deliberately over-reading and overlapping the audio, and sliding it all around afterwards until it’s in the correct place, then writing the file.
This isn’t actually a problem with data, because the CD-ROM spec actually has a 12-byte sync word, and it’s possible to extract the address from the FIFO with the data in. But the Red book spec was never intended to allow this to happen, so the data structure was designed to be fine for streamed audio, but not block extraction, which is what a fast CD-ROM drive wants to do. It’s usually safe to assume that if your fast CD-ROM drive will play audio correctly through your speakers, and supports ripping, then it will be alright. But you should be aware that there are some rogues around – most of them being older drives. I have a drive that makes a complete pig’s breakfast of the process with simple rippers – the drive has appalling characteristics anyway.
It’s the fact that audio blocks were never intended to be data blocks that makes ripping a slow process on some drives – now I hope you understand why.
If you stretch out the spiral on a CD to its full length, it’s over 4 miles long…
Incidentally, I suppose that I ought to add the following to the eight-to-fourteen modulation (EFM) bit I did earlier, so that people can get really confused:
Why does it need to be EFM? In order for the clock sub-harmonic signal to be reliably extracted from the pit data, and keep the PLL locked, the pit patterns have to be arranged so that they meet the following criteria: 1) no two ‘1’s are consecutive, 2) a minimum of 2 ‘0’s exist between two ‘1’s, and 3) a maximum of ten ‘0’s exist between two ‘1’s. In a 14-bit code, only 267 combinations satisfy these requirements, and 256 of those are in a look-up table, so that each 8-bit combination (256 bits) can be paired with a 14-bit code example and that’s what’s recorded on the CD. When the 14-bit code is replayed, then the correct 8-bit sequence is looked up in the CD player’s firmware and substituted for it. The two 8-bit sequences are then strung back together into a 16-bit sequence. So your data’s probably even more mangled than you thought…
Steve
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Graeme
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Posted - Sat Jun 16, 2001 10:34 am
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Way to go, SteveG :-) Tell it how it really is!
Maybe then, they will start to understand why there are so many caveats when users start pulling stunts with these things.
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Graeme
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Posted - Sat Jun 16, 2001 10:41 am
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| Incidentally, I suppose that I ought to add the following to the eight-to-fourteen modulation (EFM) bit I did earlier, so that people can get really confused: |
Shame on you - you forgot the coupling groups.
For anyone who has managed to follow the plot so far, there are four of these and they are placed between each EFM symbol to ensure that the 'bit placement' rules (as given by SteveG) are not violated between symbols.
For all the rest, who are totally confused by the whole thing - I'm not surprised :-)
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SteveG
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Posted - Sat Jun 16, 2001 11:04 am
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Shame on whom, Graeme? I was just adding to:
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| A ‘symbol’ is really a 14-bit word, but that’s confusing… Lastly, 3 ‘coupling’ bits are written between each symbol. Then the error correction code is added. The last thing written is a unique 24-bit sync word which identifies the start point for the frame. -myself earlier in this topic! |
Forget the coupling groups? RTFT!
Steve
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beetle
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Posted - Sat Jun 16, 2001 11:11 am
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Admittedly, I am a bit dazed! But I got!
And, thanks, Steve! THIS is the kind of thing we need here on this board! But still, I think it is a bit of a disservice to freighten newbies by telling them they are doing wring. Just give 'em the facts.
I did check my CD burner for ripping, or DAE ability, and my HP rated a 10, being best. Then I checked the Toshiba CDROM that came with my Gateway and it rated a lousy 2. And, it IS a bad performing drive.
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oldman
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Posted - Sat Jun 16, 2001 11:31 am
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| It may do well for anyone interested to pick up Ken C. Pohlman's book...ah shoot! I forgot the title and I can't find the book, but it is an excellent text book on all you want to know about digital audio. |
Beetle I think your refering to: "Principles Of Digital Audio", Fourth Edition, McGraw-Hill. Great book!
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bragov
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Posted - Sat Jun 16, 2001 11:53 am
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Thanks to all. The Pohlmann book is out of print, but I found a used copy.
Vicky
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Heavens to Betsy
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Posted - Sat Jun 16, 2001 12:04 pm
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| thanks, Steve! THIS is the kind of thing we need here on this board! |
This sort of engaging stuff innoculates oneself against a whole host of posts regarding warez or vocal eliminators.
I have a practical question for you guys:
What are the most reliable burners and software for doing so? Beetle mentioned HP...any other champs?
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SteveG
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Posted - Sat Jun 16, 2001 12:38 pm
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I have a practical question for you guys:
What are the most reliable burners and software for doing so? Beetle mentioned HP...any other champs?
-Heavens to Betsy |
Well... I've tried 3 different IDE H/Ps (all good, solid performers), a Yamaha, with which there were 'interesting' driver problems (now resolved), a Samsung dual DVD Player/CD-writer, which has complicated innards, and writes a bit slowly, but is generally OK, a USB H/P, which frightens me a bit in terms of data transfer rates, and a Plextor, which is very solid, and I'd definitely recommend. I suppose that ideally, I'd go for a SCSI drive, but I've never had any buss problems with IDEs as long as they were the master device, and weren't trying to transfer from the associated slave! - You can do this fine with BURN-proof drives, though.
I've just heard about a 20-speed Ricoh drive, but where do you get blanks certified to that speed? I wouldn't do audio that fast, anyway. This drive begs an interesting question about Laser power - I already know the answer, and I suppose I could add it, as it does answer a question that is occasionally asked.
Graeme can tell you about software, I think.
Steve
Edited by - SteveG on 06/16/2001 12:39:42 PM
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SteveG
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Posted - Sat Jun 16, 2001 3:29 pm
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Did you know that every time you put a new CD-R blank in your writer, the first thing it does is write on the disk?
(This one is understandable by all, I hope.)
Now I know that sounds odd, but it’s not actually at all. We already know that not all blanks are equal – in fact they all vary quite a bit, and so do different writers. So in order to set the right amount of power for the laser to use to change the dye states to the levels specified in the Orange book standard, the drive carries out a process called Optimum Power Calibration (OPC). There is, in the Lead-in on the disk an area where the ATIP (Absolute Time In Pregroove) length information and a write power suggestion, RORP (Recommended Optimum Recorded Power) is written, so the drive can gauge the reflectivity of the disk, and then have a stab at guessing how much power will be needed to write to the disk without splatting the dye so much that it runs into the next turn on the spiral, or writing totally inadequate pits.
It tests its guess in a reserved area before the lead-in called the power calibration area by writing a series of test pits, and then measuring the land area between them. When it finds the optimum one, it looks back at the power setting for that area, and that’s what it uses.
Of course, the power requirement varies with different writing speeds, and the power check has to take account of this. But on any drive that carries out this test competently, it should mean that recording should be optimised for all available speeds. Of course, some blanks are more consistently coated than others, and this can lead to problems. Some drive manufacturers now claim to be able to carry out this whole process during data recording, and adapt the laser power accordingly. May be this is why some drives perform better with cheap blanks than others?
There was, on early recorders, the option to just to use the RORP value encoded in the ATIP, and do no check, but this practice was abandoned ages ago because the results were totally unsatisfactory. All blanks are different, and there is a surprisingly wide tolerance in the laser wavelength allowed, which can have a significant impact on the laser power required. So the RORP-only writer is a bit of an anachronism, and if you have one, it’s definitely time to move on…
So, at normal x1 speed, the laser might test between 4.1 and 7.7 mW for a RORP value of 5.9mW, and use correspondingly higher powers for greater write speeds.
Steve
Edited by - SteveG on 06/16/2001 3:37:32 PM
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Graeme
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Posted - Sat Jun 16, 2001 4:35 pm
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| Shame on whom, Graeme? .... Forget the coupling groups? RTFT! |
Whoops - sorry.
I stand corrected, I missed that in the earlier post.
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Graeme
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Posted - Sat Jun 16, 2001 4:43 pm
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| Graeme can tell you about software, I think. |
Not really. Over the years, I've played around with all sorts of software, but settled with Nero some time ago. Although not the most comprehensive available, it does the job I need doing.
For the sort of use that most people on this forum have, Nero would be my first recommendation.
For drives, I have always had good results from Ricoh and Plextor. The Ricoh after-sales service has been exemplorary (which is a lot ore than I can say for a couple of other manufacturers of these things).
Edited by - graeme on 06/16/2001 4:50:51 PM
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Graeme
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Posted - Sat Jun 16, 2001 4:47 pm
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| But still, I think it is a bit of a disservice to freighten newbies by telling them they are doing wring. Just give 'em the facts. |
I think the problem there is that the facts are so complicated, it's even more frightening for them.
But, I agree, SteveG is doing a great job on this one.
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beetle
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Posted - Sat Jun 16, 2001 6:15 pm
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For the record, I don't think Riccoh makes burners anymore. I understand Plextor is the best out there, and are the same drives that TDK uses.
HP's Have been quirky in the past, depending on who makes the drive for a particular model.
Software? I have never had any trouble with CD Creator, although it doesn't always have featurs I want. Nero comes closer but really see no need to buy it now if Creator works solid. There are a couple of cheap brands out there now that sell at your local Target and Best Buy stores now. The CD authoring in Music match is buggy, but burns a good disc.
I wish I could find a copy of CD Architect.
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SteveG
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Posted - Sat Jun 16, 2001 6:25 pm
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| For the record, I don't think Riccoh makes burners anymore. I understand Plextor is the best out there, and are the same drives that TDK uses. -beetle |
http://www.ricoh.co.jp/cd-r/e-/e_europe/drive/index7200a.html
I think that ricoh might be a bit surprised to know that they're not making them! I'm pretty sure that they think they are!
Steve
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beetle
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Posted - Sat Jun 16, 2001 6:29 pm
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Perhaps they are just not marketing them in the U.S. anymore. TDK, HP, and Phillips pretty much dominate the US market now.
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SteveG
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Posted - Sat Jun 16, 2001 6:36 pm
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Perhaps they are just not marketing them in the U.S. anymore. TDK, HP, and Phillips pretty much dominate the US market now.
-beetle |
You may be right, on the face of it. But if you'd like a real eye-opener, try this...
http://www.ricoh.co.jp/cd-r/e-/e_asia/drive/support.html
Steve
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beetle
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Posted - Sat Jun 16, 2001 7:26 pm
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Plextor SCSI drives was a surprise! But, these companies that buy Riccoh drives still don't sell that many units in the US compared to HP, TDK, and the others mentioned.
I wonder if it matters that more IDE(ATAPI) drives sell here than SCSI nowadays.
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jonrose
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Posted - Sat Jun 16, 2001 11:15 pm
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beetle said:
I wish I could find a copy of CD Architect. |
Ouch.
If I hear of anyone willing to let loose I'll let you know. I'm not really hip on letting mine go...
All the best... -Jon
:-)
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Graeme
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Heavens to Betsy
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Posted - Sun Jun 17, 2001 8:56 am
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Good point, Beetle, on that "if it ain't broke, don't fix it." My own burning setup--Phillips and Adaptec CD Creator--works reliably. If I'm not building a house of cards in the sense of data waiting to corrupt, I'll stick with this stuff for now.
Nevertheless: thanks for the info, fellas!
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jonrose
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Posted - Sun Jun 17, 2001 12:04 pm
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Only one problem, Graeme...
Musician's Friend says it's backordered, and was due in on July 5th.
Now, I know that M.F. doesn't update their site very well either, but it is possible that they will never get any copies of CD Architect in, since it's not officially "for sale" by Sonic Foundry. Calling them produced the same result - still backordered as of today, 17 June.
I suppose Sonic Foundry may still have a small stock of this product in their warehouse, but if they did, it seems like they would have shipped it all out by now. They quit selling it in the mainstream a while ago.
Sorry beetle, and good luck in your search!
All the best... -Jon
:-)
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beetle
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Posted - Sun Jun 17, 2001 1:16 pm
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Thanks John, Graeme.
I just wonder if Sonic Foundry is putting it back into production because of the public's outcry for it, and they have come to their senses. Or is it because Musician's Friend found a supply of unsold copies.
There has no word on this from Sonic Foundry. They are mum on the issue these days. That company is in a mess these days anyway. Their stuff is buggy and poorly written. Aren't you glad Syntrillium takes their time to get it right?
Edited by - beetle on 06/17/2001 4:42:40 PM
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jonrose
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Posted - Sun Jun 17, 2001 3:46 pm
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Well, I do know that to install the latest patch, you have to upgrade to SoundForge 4.5, as 4.0 is unsupported. Fortunately, I don't really need the patch, so I won't need to waste the money on a product I may never use.
All the best... -Jon
:-)
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bragov
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Posted - Sat Jun 23, 2001 12:57 pm
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Beetle and Oldman, many thanks for recommending Pohlmann's Principles of Digital Audio. I just got it delivered and started reading it. Amazingly clear!
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beetle
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Posted - Sat Jun 23, 2001 4:26 pm
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Well, keep reading, and then tell me you understand everything, unless you're good at math and algerbra.
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oldman
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Posted - Sat Jun 23, 2001 9:50 pm
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Especially Chapter 9. If you get through that Steve G will be proud of you
Edited by - oldman on 06/23/2001 10:01:02 PM
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SteveG
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Posted - Sun Jun 24, 2001 2:16 am
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Especially Chapter 9. If you get through that Steve G will be proud of you
- oldman |
I'm already proud of Vicky - she managed to fix her C-port! And I'm sure I'd be proud of her getting through chapter 9 if only I knew what was in it... maybe someone can enlighten me, as I don't have this particular book. Perhaps I'd better start looking for a copy for when the questions start, as it's often better to be forewarned about these things. Anyone know if there's a particular reason that it's gone out of print?
Steve
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oldman
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Posted - Sun Jun 24, 2001 7:56 pm
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I guess I don't know why people think it's out of print. You can get it at Amazon.com.
SteveG; In Chapter 9 Pohlmann covers some of the basic concepts of the Compact Disc that you so adroitly discussed in your various posts. My comment was just a feeble attempt at humor. :-)
Edited by - oldman on 06/25/2001 02:39:37 AM
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SteveG
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Posted - Mon Jun 25, 2001 2:46 am
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| I guess I don't know why people think it's out of print. -oldman |
I must admit that I didn't do a search, I was relying on information provided by a certain person, whose initials are V.B., that goes something like this...
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Thanks to all. The Pohlmann book is out of print, but I found a used copy.
Vicky |
And now that I've looked at McGraw-Hill's European website I can say with some certainty that its ISBN is 0071348190, and that it was last revised in April last year. Foyles has copies, I think, so I'll get one when I'm next there.
Then oldman can post as many flaky jokes as he likes, and I might just get the point... :)
Steve
Edited by - SteveG on 06/25/2001 02:46:56 AM
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KenGAce
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Posted - Mon Jun 25, 2001 8:40 am
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"The Red book actually mentions two track pitch standards, one for 63min disks and one for 74min ones. There is some conjecture about how 74mins was actually arrived at - the best story is about some Beethoven Symphony or whatever..."
What I heard was that when it came time to decide on the max capacity of the CD, a Philips Engineer asked the German conductor, Herbert von Karajan (now deceased), what would be a suitable length. The conductor replied that it should be long enough to contain Beethoven's 9th (choral) Symphony. The performance time of this can vary also depending upon the conductor's tempo choice.
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beetle
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Posted - Mon Jun 25, 2001 8:59 am
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The story I heard was that Sony's president picked 74 minutes because that was about the length of Beehtovin's Ninth Symphony. This sounds a bit more plausible to me because Sony co-developed the CD. I think von Karajan was on a competing label.
As everyone probably knows, Sony co-invented the CD along with Phillips. Sony worked on the disc and Phillips developed the mechanical technology.
Edited by - beetle on 06/25/2001 09:02:48 AM
Edited by - beetle on 06/25/2001 09:03:27 AM
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SteveG
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Posted - Mon Jun 25, 2001 9:57 am
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Well that's really thrown a lot of light on the "why 74 minute" situation, hasn't it? Anyway since they started out at 63 mins, it rather makes a nonsense of the Karajan/Beethoven story anyway, doesn't it? Now perhaps you know why I didn't elaborate...
Steve
Edited by - SteveG on 06/25/2001 09:59:44 AM
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beetle
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Posted - Mon Jun 25, 2001 10:22 am
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Yes, but when CD's first hit the market in 1982, the maximum length of the CD was about 63 minutes. Then they rewrote the standard to allow 74 minutes soon afterward. All they need to do is revise it again for 80 minutes!  Many, many commercial CD's started to exceed 74 minutes around 1985. Players may have trouble playing them they still produce them. THAT's why I don't worry too much about the recordable CD-R's.
All i'm really concerned about with CD-R is longevity, and after three years I still haven't had any problem with any but ONE brand, Fuji.
Well, Graeme, your turn, again.
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SteveG
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Posted - Mon Jun 25, 2001 10:34 am
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| Yes, but when CD's first hit the market in 1982, the maximum length of the CD was about 63 minutes. Then they rewrote the standard to allow 74 minutes soon afterward. All they need to do is revise it again for 80 minutes! -beetle |
Stop trying to wind Graeme up! Anyway, I did a quick check on the performance lengths of Karajan Beethoven's 9th recordings, and they seem to be pretty consistently around the 67 minute mark. I think the whole story's a pile of pooh!
I do have some good news on the CD longevity front, which I'll post later, probably this evening, along with the update on the Philips variable-quality player story.
Steve
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beetle
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Posted - Mon Jun 25, 2001 11:44 am
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I can't wait! Don't let us down!
Start a new thread too.
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bragov
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Posted - Tue Jun 26, 2001 9:54 am
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Well, Beetle and Oldman, I read Chapter 9 ("The Compact Disc") of the Pohlmann book twice last night, and no, I didn't understand all of it. Had to go to my Webster's Unabridged for "anisotropic"! On the other hand, it's not a physics text, and I know more about the process than I did before.
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Graeme
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Posted - Tue Jun 26, 2001 1:06 pm
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I don't know the answer to the "why 74 minutes?" question. Obviously, I've heard much the same sories as have been bandied around here, but have never really thought there was any substance to them.
However, I'm prepared to conjecture, and I think the truth is probably a lot simpler.
It would have been in the inventors interest to claim as high a figure as possible, consistant with reliable production. Coupled with the fact that 74 minutes would probably account for both sides of two average LP's, it seems a pretty good figure on which to market the product to the end-users of the time.
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SteveG
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Posted - Tue Jun 26, 2001 2:07 pm
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Gets my vote...
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CD Writing - the Truth - or is it???