IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
A short evaluation of CDS200, Listening and looking for quality loss
Patsoe
post May 20 2003, 09:29
Post #1





Group: Members (Donating)
Posts: 591
Joined: 11-February 03
From: UK
Member No.: 4952



Reading about Cactus Data Shield after I got some CDS protected discs for my birthday, I got to wonder about the size of the errors they dare to put in. So, here we go...

At first, I ripped in EAC three times: once with my LGE CED-8080B drive, which doesn't see any errors occurring and happily finishes at standard speeds; then twice with my LiteOn LTR-48246S drive, once with caching disabled and once just having it enabled. Needless to say, the latter mode ran 10x faster on these C2 error laden discs.

The reason for checking disabled as well as enabled cache modes, is that the LiteOn returns 100% quality and reproducible data on all my scratchless discs. Expectedly, it would thus not make a difference between the two modes; I expected it would read the real value the first time, then see a C2 mismatch, and then re-read the same value 16 times or so. So, in caching mode, where only the first read is physically performed, results should be as good as in non-caching mode.
If I could prove this true, it would save a lot of time when ripping CDS discs...

Results were unexpected. Subtracting the LG-made wav from the LiteOn-made wav's gave numerous differences. This in itself is not surprising, since the drives probably interpolate differently. But some peaks were higher than 12dB, meaning they reach up into the 14th bit. This means the errors were not placed in parts which are easily interpolatable - the LG and LiteOn algorithms disagree drastically here...

Now for the caching/no-caching comparison: differences were less numerous, but still hit 12dB in some places. This means that re-reads are not reproducible with CDS discs. To check this, I ripped three more times in cached mode, and got three different CRCs. And now for the really bad stuff: I ripped once more in no-caching mode (this takes 4 hours or so), and got a different CRC than the first time. ph34r.gif

The LG drive however, returned consistent CRCs on three tries.

Resumé:
*my LiteOn is inconsistent on CDS200.
*CDS200 wasn't designed for minimal differences in interpolation.

Now for the best part: I never heard any pops or clicks, nor could I ABX any sample parts. laugh.gif

Resumé continued:
*I shouldn't care since data is flawless as far as my hearing is concerned.
*perhaps CDS200 was designed for proper masking of errors.
*I realize that I cannot not care - I want proper copies!!! tongue.gif
Go to the top of the page
+Quote Post
Pio2001
post May 20 2003, 12:22
Post #2


Moderator


Group: Super Moderator
Posts: 3936
Joined: 29-September 01
Member No.: 73



QUOTE (Patsoe @ May 20 2003 - 11:29 AM)
*CDS200 wasn't designed for minimal differences in interpolation.

I don't think you can conclude this.

To begin with, do both of your drives interpolate ? Maybe one interpolates, and the other mutes, or holds.
Then, in Tigre's tests, there were some contiguous errors. Even if your drives interpolate, it is unlikely that they can interpolate more than one sample at once. So CDS200 might still have been designed to produce errors that can be perfectly concealed on Hifi players only, that can interpolate several samples at once.

But Tigre's tests also showed a repetitive pattern of errors, meaning that anyway, they are not related to the audio signal.

On the other hand, the fact that some drives are consistent and other inconsistent with CDS200 is news for me. Thank you for having tested.
Go to the top of the page
+Quote Post
Patsoe
post May 20 2003, 13:00
Post #3





Group: Members (Donating)
Posts: 591
Joined: 11-February 03
From: UK
Member No.: 4952



Thanks for the other topic; I missed it when I was searching for an appropriate place to post this...
QUOTE
To begin with, do both of your drives interpolate ?

You're right, I don't know that. As the errors were inaudible, I presumed they both interpolated.
QUOTE
On the other hand, the fact that some drives are consistent and other inconsistent with CDS200 is news for me.

Actually, I found a remark about that by Tigre in the other thread:
QUOTE
On the last track of the disc EAC tells "Copy OK", but everytime I copy/extract it CRC is different. On the other tracks CRC is the same all the time for each drive, but doesn't match between the drives.

I will check back if the differences in my rips are only in the last samples (I ripped entire disc images). I didn't pay attention to that. Thanks!
Go to the top of the page
+Quote Post
Pio2001
post May 20 2003, 23:17
Post #4


Moderator


Group: Super Moderator
Posts: 3936
Joined: 29-September 01
Member No.: 73



QUOTE (Patsoe @ May 20 2003 - 03:00 PM)
Thanks for the other topic; I missed it when I was searching for an appropriate place to post this...

But it's in the FAQ !

Maybe the "FAQ" should be called "best of HA", or something like that...
Go to the top of the page
+Quote Post
atici
post May 20 2003, 23:23
Post #5





Group: Members (Donating)
Posts: 1180
Joined: 21-February 02
From: Chicago
Member No.: 1367



QUOTE (Patsoe @ May 20 2003 - 03:29 AM)
then twice with my LiteOn LTR-48246S drive, once with caching disabled and once just having it enabled. Needless to say, the latter mode ran 10x faster on these C2 error laden discs.

Do you mean the "Drive caches audio data" box ? That should slow down the extraction because EAC should clear the cache continuously. It is not a relaxation of the ripping process and should theoretically give better rips.


--------------------
The object of mankind lies in its highest individuals.
One must have chaos in oneself to be able to give birth to a dancing star.
Go to the top of the page
+Quote Post
Patsoe
post May 21 2003, 07:51
Post #6





Group: Members (Donating)
Posts: 591
Joined: 11-February 03
From: UK
Member No.: 4952



QUOTE (Pio2001 @ May 20 2003 - 11:17 PM)
QUOTE (Patsoe @ May 20 2003 - 03:00 PM)
Thanks for the other topic; I missed it when I was searching for an appropriate place to post this...

But it's in the FAQ !

Maybe the "FAQ" should be called "best of HA", or something like that...

unsure.gif Sorry about that...

QUOTE (atici @ May 20 2003 - 11:23 PM)
Do you mean the "Drive caches audio data" box ? That should slow down the extraction because EAC should clear the cache continuously. It is not a relaxation of the ripping process and should theoretically give better rips.

I know smile.gif. But here, I am assuming the drive does perfect on first read (with cds in good condition); and it seems that is a reasonable assumption, if differences only occur at the end of the disc. I haven't looked into that yet.
Go to the top of the page
+Quote Post
Pio2001
post May 21 2003, 11:22
Post #7


Moderator


Group: Super Moderator
Posts: 3936
Joined: 29-September 01
Member No.: 73



QUOTE (Patsoe @ May 21 2003 - 09:51 AM)
unsure.gif Sorry about that...

It's not just you, lately, I have often redirected people to the FAQ. I'm glad I made this FAQ so as to have the answers at hand.
Go to the top of the page
+Quote Post
Patsoe
post May 23 2003, 23:53
Post #8





Group: Members (Donating)
Posts: 591
Joined: 11-February 03
From: UK
Member No.: 4952



I am very sorry to have found differences between rips with the same drive in the middle of the disc, too. Still, nothing audible though.

I find it very remarkable. The two drives I use always agree with eachother and return identical second rips of red-book compliant cd's.
I can understand why they disagree with eachother on these CDS cd's, but I can't see why subsequent rips should differ.
Go to the top of the page
+Quote Post
LordSyl
post May 24 2003, 00:13
Post #9





Group: Members
Posts: 198
Joined: 19-October 02
From: Valencia
Member No.: 3577



LG's CD-Rom drives ar't death. At least with the experience I've had:
My CDs have CRCs noted, so I need to use secure mode the first time, then burst and just check track integrity by looking at the CRCs.

My brother has a LG 8x burner and it CANNOT correctly rip in burst mode even original unscratched CDs!!.
One thing is to have random read errors in some tracks when ripped in burst mode due to the drive uncontrolled reading speed, and another is that 60% of the tracks are badly read, while retrying 'em gives also faulty results...it had to use secure mode to rip correctly. (In conclusion, I doubt that the drive could be even called "CD player...").

I've got a Pioneer DVD 105 and Yamaha 8424S drives that aren't the fast type (secure mode 3'4x, burst 11x - 16x) but rarely have any error when ripping@burst mode; if they somehow do, retrying that track gives the correct result.

This post has been edited by LordSyl: May 24 2003, 00:14
Go to the top of the page
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 1st October 2014 - 19:29