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Topic: CDex and offsets (Read 4412 times) previous topic - next topic
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CDex and offsets

I'm wondering if I should use the same figure for both Start and End offset in CDex as I use for the 'read' offset with EAC, or if this is somehow completely unrelated, or whichwhat.

Perhaps it allows an even finer-tuned offset correction than EAC with a distinction of start and end read offset, but I'll be danged if the help file says anything about helpful about it. 

CDex and offsets

Reply #1
1. You should use the same figure for both start and end offset in cdex.

2. You should NOT use the same read offset value as you use in EAC for CDex. EAC measures offsets in samples, CDex measures them in CD-DA sectors (much less accurate). One cd audio sector contains 588 samples. So you divide your EAC offset with 588 and round of the result to nearest integer and use that for CDex offset. That's as accurate as you'll get (if your drive supports needed overreading).

EXAMPLE:

My Sony DDU1621 dvd-rom drive has a measured and repetable read offset of -594. That means it starts to read -594 samples too early. Therefor I have a "Read sample offset correction value" of +594 in EAC to compensate for the early read start.

Now, my DDU1621 cannot read data from lead-in or lead out, so improperly mastered/burned discs will be ripped with even a bigger data loss in the lead-in/lead-out area, if data is pressed/burned there. You can find overread capability by using the Nero CD-Speed Advanced DAE test.

With my DDU1621 of I use the above "1 sector" offset in CDex for both start/end, then I'll lose 6 samples from the beginning of each audio track ripped with CDex. I've verified this using EAC compare wavs feature.

So, EAC is more accurate in how it allows for offset correction than CDex. Which program you use is totally up to you. Only you can decide whether utmost accuracy is important to you or not.

cheers,
Halcyon

 

CDex and offsets

Reply #2
Ah ah, thanks.  I figured it would be a strange situation in which the start and end offsets should differ, and I also suspected that samples vs. sectors was not merely a language translation artefact.  heh

 
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