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PI/PO/Jitter test ? - 11/25/2004 4:31:48 PM   
lexsteele

 

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Can anyone please explain what the PI/PO/Jitter test is for and what do these abbreviations mean? Sorry, new to this one.

Also, I ran a test on a disc that starts to screw up about 3/4 of the way thru the movie. It chirps and freezes and it appears the PI/PO test indicates a huge jump durring this portion of the disc. What does that mean? I've attached a screenshot for your reference.

Thx for the help!




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RE: PI/PO/Jitter test ? - 11/25/2004 6:31:34 PM   
zebra


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It is a very lose fitting description, but generally speaking <= (less than, or equal to) a PI/PO of 280 is within acceptable standards.


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RE: PI/PO/Jitter test ? - 11/26/2004 11:03:24 AM   
lexsteele

 

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But what is the purpose of the test? what do the two graphs tell me?

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RE: PI/PO/Jitter test ? - 11/28/2004 7:28:00 AM   
zebra


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Parity inner correction errors vs. parity outer correction errors.

In *theory* it tests the 'readability' of the media. The higher the graphs, the less readable.


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RE: PI/PO/Jitter test ? - 11/29/2004 1:35:14 PM   
Matthew

 

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Since a consumer DVD-ROM or Writer is not a calibrated device, it's measuring the difficult it has in reading - thereby the number of errors reported.

For that drive, it's PI (Parity Inner) and PIF (Parity Inner Failure - could not correct at PI level)
Specifications are:
1. PI <= 280 over 8 ECC blocks
2. PIF <= 4 over ONE ECC
The Sony/Liteon DVD-ROM measures at 8 ECC, so the PIF limit is taken as either 32 (OK if there are 4 errors in each block, but not if they are grouped), or a compromise of 16 (allowing an average of 2 per block)

Scanning at maximum speed, you will also tend to see an increase just because the faster read speed toward the end makes it harder to read.
If it has trouble playing video (by definition at 1x speed), then I would expect the scan not to improve much if taken at a lower speed - 4x is a good compromise, as it's about the fastest CLV speed, so even at the end, you're assessing the readability of the media and not the high speed performance of the drive.

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