Sound Quality Vs. Measurements - Page 355 - diyAudio
Go Back   Home > Forums > Member Areas > The Lounge

The Lounge A place to talk about almost anything but politics and religion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 16th March 2012, 09:04 PM   #3541
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
This is NOT TRUE, Jan. I, too, know that controlled tests will not show differences, even when they 'magically' reappear in open listening.
  Reply With Quote
Old 16th March 2012, 09:07 PM   #3542
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally Posted by tvrgeek View Post
I do hope everyone realizes the CD format is not a normal data format with error correction encoded. It has three time slots, two 16 bit audio, one control slot. It is up to the quality of the reading software to try and correct errors. It is entirely possible for a poor transport and poor rip software not to correctly capture the CD or interpolate the missing data. It is possible that a really old PC with really bad riping software and a bad transport could be so marginal, that background processes are causing read errors. Reading an audio CD is not like reading a data format cd. It does not do retries, it has no checksums. If anyone still has the whitebook, it is worth a read. Once yo have it into a data file format, then you can be pretty sure a copy will be exact.
First of all, error correction does exactly that, correct the error. After correction, there is no more error, it's (again) bit perfect.
If error correction fails, there's a fallback with error concealment which includes interpolation. In general, that IS audible.
But, if that is the case, you have substandard drives or badly scratched disks.
All this has, of course, nothing to do with Save Mode or Normal Mode.

jan
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W. S. Maugham
Check out Linear Audio!
  Reply With Quote
Old 16th March 2012, 09:09 PM   #3543
diyAudio Member
 
Join Date: Jan 2008
Location: Virginia
Quote:
Originally Posted by john curl View Post
I, too, know that controlled tests will not show differences, even when they 'magically' reappear in open listening.
I never trust my senses more than my tools (controlled tests included). Brain can play some funny tricks, especially when you WANT something to be true.

Last edited by SoNic_real_one; 16th March 2012 at 09:11 PM.
  Reply With Quote
Old 16th March 2012, 09:12 PM   #3544
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally Posted by john curl View Post
This is NOT TRUE, Jan. I, too, know that controlled tests will not show differences, even when they 'magically' reappear in open listening.
Sorry John, but what you call 'magically' is called 'perception' by the rest of the world.
It is very regretfull that you selected to ignore that area of knowledge for the last few decades.

jan
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W. S. Maugham
Check out Linear Audio!
  Reply With Quote
Old 16th March 2012, 09:26 PM   #3545
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
Finally found a copy of the ST-140 schematic. I only had a hard copy but it went when I sold mine. Just might model it for experience. It did fail the wife test. One more data point. As the "magic" mod was to replace the red LED with green, I can now see what that does to the bias of the IPS.
  Reply With Quote
Old 16th March 2012, 09:41 PM   #3546
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
Jan, when dealing with the crude error correction of a CD, error correction is a best guess, not a true correction like we do with data formats like old 7 of 9 code or GCR on the old tape drives, let alone the application layer methods. No ecc or crc bytes, no retry, no blocking out bad blocks. Dust comes and goes. It is interpolation as you suggest. There is no true error correction, as there is no redundant data from which to extract the correction. You may be surprised that trellis coding for modems corrects only to a statistical probability. We then have the transmission protocol layer request retry if a block does not check after the best guess by constellation position.

We agree on the root problem, poor drive, poor media, poor source. Killing background apps should only have an effect on really really bad software, of which plenty exists! I believe EAC tries to identify read errors and retry.

I'll still take the level of errors induced in a CD copy to those in a tape copy. I would prefer to get my music in a reliable data format that we could employ bit error correction on.
  Reply With Quote
Old 16th March 2012, 09:46 PM   #3547
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
How's this for the obvious: If you are only trying to satisfy yourself, then it does not matter if you are fooling yourself or not. Ignore measurements as it is only your perception. Be happy, don't worry. But if you are building things for someone else, you had better rely on both measurement and perception as what make them believe may not be the same as you.
  Reply With Quote
Old 16th March 2012, 09:52 PM   #3548
diyAudio Member
 
Join Date: Jan 2008
Location: Virginia
Red Book format is very redundant: has EFM encoding (eight-to-fourteen modulation), CIRC (cross-interleaved Reed–Solomon coding), L2 ECC, subcode channels and so on, which are not typically exposed to the application reading the disc. CIRC adds to every three data bytes one redundant parity byte.

Also, any decent software will retry reading a bad data in "data mode", only in "audio mode" there is no retry.
  Reply With Quote
Old 16th March 2012, 09:55 PM   #3549
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
error correction is a best guess, not a true correction
tvr, that's not exactly true. There are two types of errors- correctable and uncorrectable. In the latter case, there's interpolation. In the former, the original data is restored exactly. So the interpolations are transient events, not continuous. When I had my old Magnavox CD player, I was able to see how many interpolation errors I got. I was surprised by the results. Maybe one or two errors total in ten discs I tried. So out of 11 hours of music, interpolation was used for about 50 microseconds total.

That's in the category of things to not worry about.
__________________
And while they may not be as strong as apes, don't lock eyes with 'em, don't do it. Puts 'em on edge. They might go into berzerker mode; come at you like a whirling dervish, all fists and elbows.
  Reply With Quote
Old 16th March 2012, 09:55 PM   #3550
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
I satisfy 1000's of customers. How do I do it? Oh, of course, MARKETING!
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Quality Control differences = variations in sound quality? KT Class D 3 4th June 2014 01:02 AM
Sound Card for Measurements Marik Solid State 2 2nd January 2012 09:59 PM
Sound Card Recommendations (For Audio Measurements) dchisholm Equipment & Tools 5 16th July 2011 10:40 AM
How to protect sound card during amp measurements? okapi Everything Else 13 2nd September 2008 04:06 PM
Sound cards - test and measurements jackinnj Everything Else 2 5th July 2003 04:02 PM


New To Site? Need Help?

All times are GMT. The time now is 03:26 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2