This is a small example of EAC returning matching CRCs for extracted rips even though there are errors in these rips.
Before disc resurfacing, EAC did not report any suspicious positions for any of the secure mode rips, however it did light up the first row of the error bar on all secure rips. After the disc was resurfaced, all rips reported the same CRC and the error bar did not light up.
The following table shows the CRC values.
The most interesting feature is that before resurfacing the DVD drive returned 2 pairs of matching CRCs, both of which are wrong, the odd man out CRC is the correct one.
The other interesting feature is that the only correct rip before resurfacing was for burst mode although there is no way to show whether this was just coincidence, unfortunately no further testing could be carried out once the disc was resurfaced.
The final point is that the errors were repeatable, there were only 2 values that the data would take, the right one and just one wrong one.
RIP DRIVE MODE CRC
a LTD163 C2 rip1 CRC 4036274F
b LTD163 C2 rip2 CRC 4036274F
c LTD163 C2 rip3 CRC 809A3D61
d LTD163 NoC2 rip1 CRC 809A3D61
e LTD163 Burst rip1 CRC 8DAF0CA2
f LTD163 C2 rip1 resurfaced CRC 8DAF0CA2
g LTD163 C2 rip1 resurfaced CRC 8DAF0CA2
h LTR40125S No C2 rip1 CRC D60E061D
i LTR40125S No C2 rip2 CRC F7721A2C
j LTR40125S With C2 CRC 482F169F
k LTR40125S NoC2 rip1 resurfaced CRC 8DAF0CA2
e=f=g = corectly ripped wave
differences between rips
f-a = diff1
f-b = diff1
f-c = diff1 and diff2
f-d = diff1 and diff2
f-e = none
f-g = none
f-h = not done
f-i = not done
f-j = not done
f-k = none
I have attached a zip file with extracted waves showing the differences between the LTD163 rips. These waves show that all the differences were linear interpolations thus there were no crackles.
As per usual, the linear interpolations caused an increase in distortion which is most noticable in the higher frequencies. However as these bursts of distortion only last for about 15 milliseconds they are quite inaudible