Gap Detection: Secure vs Accurate

**RolloTomasi** · 10-03-2009

What is the difference? Number of attempts or something else?

**RolloTomasi** · 14-03-2009

Anyone happen to know the answer?

**greynol** · 14-03-2009

Hi Rollo.

I don't believe anyone really knows except Andre, but I think you're right that it's just the number of attempts.

IIRC, with method C you can hear the attempts depending on how the drive is configured to deliver audio. If you can get it to behave this way, your theory can be tested.

**RolloTomasi** · 14-03-2009

Thanks, greynol. I'll give that a try.

What I've noticed lately is some rips with wacky pregap lengths, very long ones, not on my own rips, but others. Many still use Accurate rather than Secure. But I suspect the wrong method is being used, B as opposed to A, or failing drives. Maybe just crappy drives.

I wish the Gap Detection Method was included in the log. I see that in the wish list thread.

**greynol** · 14-03-2009

The problem is that different methods work better with different drives, kind of like caching and the use of C2 pointers.

In addition, I wouldn't be surprised if there were some drives that hang when the accuracy is set to secure regardless of the method on certain discs.

**grepario** · 15-03-2009

please, someone can tell me what is the best way to choose the right method of gap detection, beetween the three metod and secure/accurate?
with a samsung S182D, I had 6 different results for combined methods.

thanks
marco

**Teller** · 15-03-2009

Originally Posted by grepario

please, someone can tell me what is the best way to choose the right method of gap detection, beetween the three metod and secure/accurate?
with a samsung S182D, I had 6 different results for combined methods.

thanks
marco

These are general rules only

Most drives do best with method A secure
if
gaps are all the same length = bad
gaps lengths are all very short 00.00.01, 00.00.03 = bad
gaps lengths are very long. Over 1 minute = bad
gaps lengths get progressively longer, or are equal to the length of the track or the total exceeds 30 seconds (2,250 sectors) = bad

Please don't write me to tell me you have exceptions, I know they exist.
These are general rules only

**grepario** · 15-03-2009

thanks for your reply.
Infortunately with these rules I can leave only detection method C, ohers methods pass the general rules and hae differents results frpm one to one other.
I've tested also my cd-dvd drive sony AW-G170A with same results.
Now if there is'nt ONE and ONLY right method of gap detection, all of our efforts to make sure copies 1:1 are vain, because there will be never two equal rip with equal gaps detection?
Is possible that all the two my drives are exceptions?
thanks.

**greynol** · 16-03-2009

I whole-heartedly agree with Teller.

The thing people either fail to believe or fail to understand is that 00 index information does not have to exist for every frame and has no redundancy for error correction. If different methods give different results it may very well be that one might not be any more "correct" than the other!

**grepario** · 16-03-2009

I don't worry a lot about the differences that are among the various methods of survey of the gap, butI see that in the communities that use EAC the objective it is to make it possible to check if the copy of an original were exact, for example, reading it's code crc, in comparision with one other or to verify it through accuraterip. everything this doesn't have sense if the method of survey of the gaps give different results, because the copies put to comparison will result not equal . Or am I wrong ?

**Teller** · 16-03-2009

Find someone who has a genuine Plextor drive and compare your results.

**greynol** · 16-03-2009

Although Plextors are great for their ability to overread, read HTOA, provide reliable C2 error information, make use of the FUA bit and have somewhat above-average abilities in getting accurate data from damaged discs, I haven't found their gap detection to be all that great.

@grepario:
Either you didn't read my post or you simply don't understand what I said. Precise gap information down to the exact frame is not always possible. Furthermore, it's really nothing worth worrying about.

**wyhiwyg** · 02-04-2009

> with a samsung S182D, I had 6 different results for combined methods.

Try using a disc where you know the gaps are 0 (such as with some deejay mixed CD). This is assuming that you don't have another drive that you can confirm the correct gaps with.

**Teller** · 04-04-2009

A great example of general rules:
gaps lengths are very long. Over 1 minute = bad
gaps lengths get progressively longer, or are equal to the length of the track or the total exceeds 30 seconds (2,250 sectors) = bad

In this case the total gap length for just tracks 7 to 10 exceed the total length of the disc (>80mins)

Code:

Exact Audio Copy V0.99 prebeta 4 from 23. January 2008
EAC extraction logfile from 1. April 2009, 22:19
Day Without Dawn / Understanding Consequences
Used drive  : TSSTcorpDVD+-RW TS-L632H   Adapter: 1  ID: 0
Read mode               : Secure
Utilize accurate stream : Yes
Defeat audio cache      : Yes
Make use of C2 pointers : No
Read offset correction                      : 6
Overread into Lead-In and Lead-Out          : No
Fill up missing offset samples with silence : Yes
Delete leading and trailing silent blocks   : No
Null samples used in CRC calculations       : Yes
Used interface                              : Native Win32 interface for Win NT & 2000
Gap handling                                : Appended to previous track
Used output format              : User Defined Encoder
Selected bitrate                : 128 kBit/s
Quality                         : High
Add ID3 tag                     : Yes
Command line compressor         : C:\Program Files\FLAC\flac.exe
Additional command line options : V -8 -T "artist=%a" -T "title=%t" -T "album=%g" -T "date=%y" -T "tracknumber=%n" -T "genre=%m" %s
TOC of the extracted CD
     Track |   Start  |  Length  | Start sector | End sector
    ---------------------------------------------------------
        1  |  0:00.00 |  7:21.30 |         0    |    33104
        2  |  7:21.30 |  4:32.18 |     33105    |    53522
        3  | 11:53.48 |  1:19.16 |     53523    |    59463
        4  | 13:12.64 |  3:36.24 |     59464    |    75687
        5  | 16:49.13 |  6:53.68 |     75688    |   106730
        6  | 23:43.06 |  4:40.70 |    106731    |   127800
        7  | 28:24.01 |  1:27.62 |    127801    |   134387
        8  | 29:51.63 |  4:19.62 |    134388    |   153874
        9  | 34:11.50 |  4:58.55 |    153875    |   176279
       10  | 39:10.30 |  7:48.30 |    176280    |   211409
Track  1
     Filename C:\Users\Daniel\Documents\FLAC\Day Without Dawn\Understanding Consequences\01 - The Wake.wav
     Pre-gap length  0:00:02.00
     Peak level 100.0 %
     Track quality 100.0 %
     Test CRC DC75BC4F
     Copy CRC DC75BC4F
     Track not present in AccurateRip database
     Copy OK
Track  2
     Filename C:\Users\Daniel\Documents\FLAC\Day Without Dawn\Understanding Consequences\02 - After the Banquet.wav
     Peak level 100.0 %
     Track quality 100.0 %
     Test CRC CCEF2FCF
     Copy CRC CCEF2FCF
     Track not present in AccurateRip database
     Copy OK
Track  3
     Filename C:\Users\Daniel\Documents\FLAC\Day Without Dawn\Understanding Consequences\03 - The Sea of Fertility.wav
     Pre-gap length  0:04:32.18
     Peak level 100.0 %
     Track quality 100.0 %
     Test CRC 1CD06D48
     Copy CRC 1CD06D48
     Track not present in AccurateRip database
     Copy OK
Track  4
     Filename C:\Users\Daniel\Documents\FLAC\Day Without Dawn\Understanding Consequences\04 - Seducing the Dead.wav
     Pre-gap length  0:05:51.34
     Peak level 100.0 %
     Track quality 100.0 %
     Test CRC 65212957
     Copy CRC 65212957
     Track not present in AccurateRip database
     Copy OK
Track  5
     Filename C:\Users\Daniel\Documents\FLAC\Day Without Dawn\Understanding Consequences\05 - The Deeper Wells.wav
     Pre-gap length  0:09:27.58
     Peak level 100.0 %
     Track quality 100.0 %
     Test CRC A3739A1A
     Copy CRC A3739A1A
     Track not present in AccurateRip database
     Copy OK
Track  6
     Filename C:\Users\Daniel\Documents\FLAC\Day Without Dawn\Understanding Consequences\06 - A Cruel Statue.wav
     Pre-gap length  0:16:21.51
     Peak level 100.0 %
     Track quality 99.9 %
     Test CRC C77B6982
     Copy CRC C77B6982
     Track not present in AccurateRip database
     Copy OK
Track  7
     Filename C:\Users\Daniel\Documents\FLAC\Day Without Dawn\Understanding Consequences\07 - A Fast-Paced Futuristic Thrill Ride.wav
     Pre-gap length  0:21:02.46
     Peak level 50.1 %
     Track quality 100.0 %
     Test CRC 8171A9D3
     Copy CRC 8171A9D3
     Track not present in AccurateRip database
     Copy OK
Track  8
     Filename C:\Users\Daniel\Documents\FLAC\Day Without Dawn\Understanding Consequences\08 - The Second-to-Last Page.wav
     Pre-gap length  0:22:30.33
     Peak level 100.0 %
     Track quality 100.0 %
     Test CRC D00CCC28
     Copy CRC D00CCC28
     Track not present in AccurateRip database
     Copy OK
Track  9
     Filename C:\Users\Daniel\Documents\FLAC\Day Without Dawn\Understanding Consequences\09 - Your Diminutive Hand.wav
     Pre-gap length  0:26:50.20
     Peak level 100.0 %
     Track quality 100.0 %
     Test CRC 018A17DB
     Copy CRC 018A17DB
     Track not present in AccurateRip database
     Copy OK
Track 10
     Filename C:\Users\Daniel\Documents\FLAC\Day Without Dawn\Understanding Consequences\10 - The Undertide.wav
     Pre-gap length  0:31:49.00
     Peak level 100.0 %
     Track quality 100.0 %
     Test CRC 122075AB
     Copy CRC 122075AB
     Track not present in AccurateRip database
     Copy OK
None of the tracks are present in the AccurateRip database
No errors occurred
End of status report

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