Disc Quality tests
Having recorded the maximum amount possible onto the Philips 16x DVD+R media at its rated recording speed of 16x 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 Philips 16x DVD+R media recorded on each review recording device with the Plextor PX-755A 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.
"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 methodoligy for determing these factors. These are my own personal views and by no means as accurate as an Industry C.A.T.S scan 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 expect that not every piece of media is capable of producing this
with such influences as excepted media/ hardware tolerance levels having an impact but I will 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 determine 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. Thats 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:
Taking into account all tests carried out during this stage of the review, it is clear to see that recording at 16x didn't always mean that a good quality recording had been achieved. More so, if I had only shown you the Sum8 and Sum1 tests, the obvious poor jitter towards the end of the NEC ND-4551 recording would not of been noticed. This drives recording had very acceptable Sum1 and Sum8 results but the poor jitter does suggest that slowing the speed down to 12x would be a wise move for better quality under the firmware revision used in this review.
The BenQ DW 1640 however, achieved a very good overall level of quality Vs recording speed. As the BenQ drive uses the same hardware as Philips drives this comes as no surprise and shows that a quality 16x recording is possible. The Plextor quite often will use a 12x strategy for 16x media to obtain the best quality possible. With Power Record enabled a very good level of quality was achieved. Anyone who uses Plextor drives and Power record will know all bout the way the Plextor can adjust recordings to any media dependant on a disc to disc basis to obtain good quality recordings.
As I would expect on a 100% under speed the quality og the Pioneer recordings was very good indeed. Also, again as expected at a slow default speed of 4x only, the LG 4166B recording was of a decent quality but it certainly cannot be classed as having any sort of optimised support for the Philips 16x DVD+R media.
In the extra tests carried out on this media, I found that leaving Solidburn enabled for known media on the BenQ DW 1640 helped lower the reported Jitter after a couple of discs of learning. Although not a big drop it all helps but it can add an extra 15 seconds onto the recording time. With the Plextor PX-755, a new strategy was created in the Auto Strategy database using the full burn (destructive ) mode. This new stategy was then used to see if any improvement in speed or quality was noted. I found during these tests that using the default recording strategy in place worked better than creating a new one under present firmware.
"Please note that you will need a compatible drive for doing these scans such as the Plextor PX-755A 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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