Disc Quality tests
Having recorded the maximum amount possible onto the Verbatim 8x DVD-R Dual Layer media at its rated recording speed of 8x and above to all available review drives with Nero CD-DVD Speed, the next stage of this review will concentrate on Disc Quality.
The first part of the Quality tests involved scanning all the pieces of Verbatim 8x DVD-R Dual Layer media recorded on each review recording device with the Plextor PX-760A using Plextools Q-Check tests to find out how many potential SUM8 (PI Errors) and Sum1 (PI Failures) a playback device would have to correct whilst playing or transferring the recorded media. This also enabled me to obtain which of the 5 recorded pieces of media most matched the average result. The average disc shown below was then subjected to a Beta and Jitter test. Although more tests are available I believe I am showing the most common factors in overall disc quality for the average user.
"As the whole purpose of reviewing media for our readers is to try and obtain a good idea of the average quality of a given media, I have come up with this new methodology for gauging these factors. These are my own personal views and by no means as accurate as an Industry C.A.T.S device for measuring the quality of a disc but I believe I have come as close as I possibly can do with the equipment available to the average user."
I will not expect that every piece of media is capable of producing this
with such influences as media/ hardware tolerance levels and packing/delivery methods having an impact. I will however expect the results not to consistently stray too far from set standards for a recommended media. It is also the sum of all tests that I use to gauge the overall quality of the media and not one test alone.
The less Sum1 and Sum8 that are found on a media then in theory the better the chances are of good long term playback for this media without data loss becoming a significant problem. That's not to say that recordings with high Sum1 and Sum8 levels will be bad - the error correction logic of DVD playback and transfer devices are capable of correcting many potential errors. There is just more chance they might be affected by such influences as dirt or fingerprints. Different scanning devices scan slightly differently but basic guidelines using a Plextor drive are that Sum8 should not exceed 280 for sustained periods and Sum1 should not exceed 4 for sustained periods. You don't want to see any reported POF's (Parity Outer Failures) as these normally should result in uncorrectable errors!
Jitter and beta must remain within set specifications for a Plextor scan (Beta should not exceed +15 or -5 for sustained periods with the more level the result the better). Jitter should stay within the lower half of the graph for best results. Reading devices with good jitter correction ability should be able to read higher reported levels better than those that don't.
Overview of Disc Quality results:
It is fair to say that all used recording devices have recording stragegies in place which get the job done within set specifications. That said, some recording devices delivered better results than others. The Optiarc AD-7173A and Plextor PX-760A seemed to have a good understanding of the Verbatim 8x DVD-R Dual layer media, whilst recording devices such as the Samsung SH-S182 and Pioneer DVR 111D could have some improvemnts made. The Liteon-It SHM-165P6S offered the middle ground with a decent recording quality being offered.
"Please note that you will need a compatible drive for doing these scans such as the Plextor PX-760A I have used in this review for making my decisions on the potential quality of this media. Other drives you could try include BenQ, Liteon, NU TECH and ASUS branded writers, but only the Plextor drives with Q check functions offer the full range of tests."
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