[hciman77]

Quote:

Originally Posted by musicexpression /img/forum/go_quote.gif i would think that for redbook CDA format, the error detection/correction/recovery capabilities of the playback machine has an sonic impact on CDR playback. AFAIK, audio CDs are EFM-encoded as a form of data-interleaving to "spread" the probability of read errors across a few frames of encoded information, such that a single scratch on the CD surface does not cause any audible effects. so it's up to the error-recovery mechanism that tries to guestimate and makeup the errored part. how well it does may have an impact on the perceived quality.

From what I understand the bit error rate on audio CD playback is about 1 (inaudible) sub-ms error per 5 minutes maybe on a really badly gouged CD this would be an issue but on even a half decent CD this simply should not be a problem.

From rec.audio.opinion
---------------------

BER is somewhat less than one in ten million for virtually all modern CD
players and transports, for concealed (best guess interpolated) errors.
Such errors are almost certainly inaudible. Unconcealed but muted errors
occur at a rate of around one in one billion, that is less than one per
CD on average. The moral - FORGET bit error rate.

and........

From Pohlman (Principles of Digital Audio), we learn:


"CIRC can enable complete correction of burst errors up to 3874
bits (a 2.5-mm section of pit track)


"Theoretically, the raw-bit error rate (BER) on a CD is between
10^-5 and 10^-6, that is, there is 1 incorrectly recorded bit for
every 100,000 to 1 million bits on a disc. Following CIRC error
correction, the bit error rate is reduced to 10^-10 or 10^-11,
or less than 1 bad bit in 10 to 100 BILLION.


At 74 minutes for a CD, 44,100 samples per second, 16 bits per
sample, 2 channels, a CD holds some 195 million samples, nearly 800
million bytes, or some 6265728000 bits. COmpare that to the
corrected error rate of 1 in 10 billion bits.

and.....

Mr. Pinkerton has provided the following in the past:

http://x23.deja.com/getdoc.xp?AN=567713397


"Typical figures for uncorrected but concealed errors from 'plain jane'
mechanisms such as the ubiquitous Sony CDM-14 and Philips CDM-12 series are
of the order of one in ten to twenty *million* samples, i.e. one inaudible
sub-millisecond 'best guess' sample every five minutes or so. Really bad
'muting' errors are a bit less than one per disc on average"

http://www.treworgy.com/cdr/test.html shows that entire audio CD's can be
read without one bit being read incorrectly.

 

[HiWire]

The problem doesn't lie with pressed CDs so much as the copied media... here's an example of a new DVD burner's performance against media errors:

http://www.cdfreaks.com/reviews/Sony...rformance.html

You can see that some media are higher quality than others - there are at least 2 variables here - the media quality and the burner's ability to compensate for errors.

 

[varsitypride3]

Quote:

Originally Posted by gonglee /img/forum/go_quote.gif meant 96000 khz sampling rate, and 24 bits, instead of 192 kbps. If you try it, you will definitely hear a difference, and you will thank me then. It gives soul to digital, if you thought it was lacking it. If you have a program like protools, you can even go higher with the upconversion, but the program is pretty expensive - $600 with the hardware. I am listening to a CD I burned now - when I compare it with the red CD I bought, it's no brainer - after you try it, you will burn your entire CD collection like me.

No, you don't mean 24 bits and 96000 khz. You outlined how to convert music to 192 kbps and once everyone told you that you were compressing (not enhancing) the music, you changed your story. Windows Media Player can't upconvert to 24 bits--and even if it did, whether or not it improved sound quality would be controversial, at best. You can't improve upon the source-- you can just buy equipment that does a better job of providing a signal as true to the source as possible. In the end, we (the end users of the product) are limited by our music. Not much you can do about that. But some will always argue you can--and this is what makes this hobby so ripe for discussion

-cris

 

[immtbiker]

Cd burner manufacturers recommend burning at slower speeds because it allegedly makes the pits more square instead of having rounded edges and this would give the laser a chance to get a better reading which equates to better SQ. I can see that, being that jitter and transport stability is essential for optimum playback.
But I would think that if the original store bought CD was burned quickly and poorly, then a CD-R copy cannot magically improve the 0's and 1's. Also converting 16 bit to 24 bit is interpolation and unless it is recorded in 24 bit and played back at 24 bit without downsampling, then the upsampling conversion will never be true to the source recording.

 

[bigshot]

Quote:

Originally Posted by immtbiker /img/forum/go_quote.gif Cd burner manufacturers recommend burning at slower speeds because it allegedly makes the pits more square instead of having rounded edges

Do you happen to know a manufacturer that mentions that on their site? I did about fifteen minutes of googling, and couldn't come up with any. I've always been told that burners are optimized to work at a particular speed, usually their fastest rated one. Burning at extremely low speeds can introduce more error, not less.

Rounded edges on pits would suggest that the disk was rotating faster than the laser is turning on and off... that's unlikely, isn't it?

See ya
Steve

 

[Herandu]

It is absolutely true that burning at a far slower speed does make a difference. Engineers like me who have had to burn promo, back up, etc. material onto CDs for years picked this up long time ago. The simplest test for this is to burn 1 each of an audio CD at different burning speeds. Mark the speed on it. Now play them back in your car for a week or two. The highest recorded speed one should start to skip or refuse to play far quicker than the others.
As for whether it is possible to improve the quality of a CD, or get an improved copy of a damaged CD by burning it again: It is possible as well. Again, burning a new copy of damaged discs as part of my job has shown me that to be true. I can guess the reasons, but that's another matter.

 

[Don Quichotte]

Quote:

Originally Posted by bigshot /img/forum/go_quote.gif Rounded edges on pits would suggest that the disk was rotating faster than the laser is turning on and off... that's unlikely, isn't it? See ya Steve

I'm afraid not. The laser power does not go from 100% to 0% and back instantly, there is a very short transition period. Because of this, the border between the pits and the lands is not so very neat, and less so as the recording speed is higher. This is the reason why Yamaha introduced the "Audio Master Quality Recording" technology in their top of the line F1 burner a few years ago, taken over by Plextor later on and introduced in the Premium 2 burner. Plextor Premium 1 also supports a version of AMQR, namely the Gigarec recording with values of 0.8, 0.7 and 0.6. This means recording the information on a greater surface of the disc, so that fewer (and therefore wider) pits and lands are recorded on any given spirale on the disc. The reduced data density makes it easier for the CD player to differentiate between the pits and the lands, but of course the CD transport will have to rotate the disc faster than a "normal" disc. I can definitely hear the difference between a "normally" recorded disc and one recorded with Gigarec on my Plextor Premium (1).
What I don't understand is the mechanism which translates these differences between "easier" and "harder" to read into sound differences, given the fact that almost all decent CD players are bit perfect readers. I remember reading some speculations about the harder working CD transport emitting more EMI which the power supply and other components are picking up, or something like this, and I also thought about jitter, as I said before, but I'm not qualified enough to judge these hypothesis. Something must be going on, though...

 

[gonglee]

Burwen Bobcat is the software that claims it can make regular CDs sound like SACD, but it's pricy for a software - $199. You can google search for it.

It's simple to experiment your-self. All you need is a Taiyo Yuden CDr, and burn it at the slowest speed allowed by your burner.

Use EAC program to rip, and feurio to burn ( both can be had for free - google search for them ).

I haven't tried the Bobcat yet, so I am not recommending it yet.

When I come across a CD with a sound I don't like, I add some effects to it, and it becomes better. I use protools but it's quite expensive - mbox with the hardware is $600.

There must be other recording programs out there you can use as well, for less. You can try adding reverb and delay to CDs that sound too dry.

If you like the way your burned Cd sound better than the Red book Cd, you might want to get a Plextor burner that will further improve the quality.

When you are burning it, close all the programs - even the ones running on the background like anti-virus. Also don't do anything on the computer - don't even touch the mouse, and you will be rewarded with a better sounding product.

 

[fjf]

I wonder how can we install programs from CDs. Even from CD-Rs. They should not work at all, with all those corrupted bytes

 

[HiWire]

I would think that burning at higher speeds is prone to error for mechanical reasons as well - a slightly unbalanced cheapo CD-R will become more unbalanced as the RPMs increase. Thus the urban myths about CD-ROM players exploding CDs at extremely high speeds (e.g. 52X). This is the same basic principle as tire balancing - most CDs are not perfectly round or perfectly balanced.

 

[jimholt]

Quote:

Originally Posted by HiWire /img/forum/go_quote.gif I would think that burning at higher speeds is prone to error for mechanical reasons as well - a slightly unbalanced cheapo CD-R will become more unbalanced as the RPMs increase. Thus the urban myths about CD-ROM players exploding CDs at extremely high speeds (e.g. 52X). This is the same basic principle as tire balancing - most CDs are not perfectly round or perfectly balanced.

Perhaps thats why some people hear the audible changes when they lathe their cd's. Jim.

 

[immtbiker]

Quote:

Originally Posted by bigshot /img/forum/go_quote.gif Do you happen to know a manufacturer that mentions that on their site? I did about fifteen minutes of googling, and couldn't come up with any. I've always been told that burners are optimized to work at a particular speed, usually their fastest rated one. Burning at extremely low speeds can introduce more error, not less. Rounded edges on pits would suggest that the disk was rotating faster than the laser is turning on and off... that's unlikely, isn't it? See ya Steve

It was a tech from Aleratec:

http://aleratec.com/11cdcocr52xs.html

He explained the whole process to Stevieo who then explained it to me. It might be on their site.

 

[bigshot]

In my job, I've burned many thousands of CD-Rs and DVD-Rs. It's archive policy to verify every burn. I've found a wide variance in burn quality with different stock, but I've never seen any correlation between speed and accuracy. I currently use Taiyo Yudin stock burned at top speed and the reject rate is less than 1 in 500. The rejects were still perfectly playable.

See ya
Steve

 

[Chops]

It doesn't matter what speed you record at or what bit rate you convert to, the copy can ONLY sound as good as the original. (unless it is remastered or enhanced in some way)

That's like saying a single dollar bill is worth more straight from the bank than it is from a store as change.

 

[*645-k701]

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