PX-755SA - Does Autostrategy Continue Learning?

vbimport

#1

I’m new to the Plextor scene with a PX-755SA. Thus far, I enjoy fiddling with all the tools but I’ve not been overly impressed with burn quality on the two brands of DVD media I’ve tried, MCC 004 (CMC from Office Max) and Yuden T02 (older, non-hub printable, from Rima). With Autostrategy on Auto, strategies were created for both. This helped some with the MCC 004 (I settled on 8X), but the Yuden T02 (which I’ve only tried twice at 8X) still seems dicey (ugly transfer rate tests on my LiteOn SH-16A7S).

Does Autostrategy continue to learn and fine-tune the initially-stored strategy with each burn? The only thing I could find by searching was at http://club.cdfreaks.com/showpost.php?p=786466&postcount=15 – which suggests that Autostrategy does continue learning. Has this been verified?

Thanks!


#2

I don’t think it does. :slight_smile:
But usually MCC 004 and YUDEN000 T02 work well with default strategies too… or have I missed something?


#3

Assuming you’re right, that’s a shame. I did try the defaults (AS Off PR On), and the Yuden T02 burned better (8X) but still exhibits a rough transfer rate curve on the LiteOn. The default for CMC MCC 004 seemed relatively poor (at least at 12X).


#4

Why not try 16x for the MCC 004?


#5

Possibly undue caution from past experience where 16X burns (on a now-retired NEC ND-3500A) looked great (perfect transfer rate curve) but skipped/froze on some of my set top players.


#6

Where is HWP? Thought he might have some input to an answer to the original question. Inquiring minds want to know (hopefully definitively).


#7

Reporting for duty, SIR! :smiley:

Unfortunately both Plextor and Taiyo Yuden (the inventor of AutoStrategy) have been rather tight-lipped about the internals. So I can only offer you my conclusions based on my own observations.

I don’t think AS is ‘learning’ in a way that it is getting gradually better as it burns more discs of the same type, as one might think when seeing the link you provided (BTW: Remember that the results shown in the link were done with the first version of AS, as implemented in the PX-716). The reason for this assumption is based on the main problem that AS is supposed to cure: Variance in media quality.

Even with top quality manufacturers every disc is slightly different from another. With low quality manufacturers that difference can be quite huge. This makes the task of implementing a writing strategy that works fine for all discs of that manufacturer an almost impossible task, especially in combination with 16x burning (where even slightest variances become emphasized due to the speed). Hence the invention of AS that can modify the base strategy to suit each individual disc according to its variance. The media used in the link you quoted were CMC-MAG-E01-000 (8x +R) and CMC is well known for having wide margins of quality from time to time.

Now ‘learning’ in a way of gradually getting better the more media of the same type you burn only works, if the media used are (rather strictly) all very much the same. You cannot fine tune something over several tries if the object of your tuning is changing constantly.

So why does the linked result look like the burn got gradually better? Well, for burning results with AS two main factors come into play: The individual quality of the disc inserted and whatever strategy AS is creating for it.

[Side note: Especially the latter factor can be a real PITA if you are using high quality media. If AS decides to use a just so slightly different strategy from one to the next burn you’ll end up with a different error-pattern and eventually worry if your current stock of high quality Yuden discs is maybe junk half way down the spindle. It also makes testing and comparing rather difficult since you can never tell if you’re actually seeing the result of the same writing strategy, never mind the quality of the disc used.]

So in the case you linked maybe the first disc was not so good or AS came up with only a sub-optimal strategy or maybe even both; the second was an maybe an OK disc and/or AS worked just fine while the third was even slightly better and AS used the same strategy as in the second case (anyway the difference is to small to be sure). Also in the end the number of the tests compiled is to small to be sure IMHO. It could well be that the next burn would have show worse results again.

Without more knowledge on the internals and more professional testing equipment it’s very difficult to say what the true cause for the results is. The folks over at www.cdrinfo.com have started to use professional testing equipment from Datarius. I sure would like to see them taking a deeper look at AS.


#8

HWP - thanks for responding. Duty performed admirably!

This enlightened me on at least one important point, if I understand it correctly: “Hence the invention of AS that can modify the base strategy to suit each individual disc according to its variance.” I had assumed that once an Autostrategy strategy was created, that that strategy would be enforced without variance for each subsequent burn on a disc of the same type - thus not taking into account each individual disc according to its individual variance.


#9

The original AS, as implemented in the PX-716, would not allow for this. However the newer “Advanced AS”, as implemented in the PX-755 and 760, does allow for this.

Once an AS-strategy is created you can force the drive to exclusively use that strategy by setting AS to “ON”-mode in Plextools. This will only use existing AS strategies for burning but not create new ones. In contrast to that, “AUTO”-mode will let the drive select between a firmware-strategy, an already existing AS-strategy or a newly created AS-strategy as it sees fit.


#10

Thanks for clarifying, and enhancing my understanding.

Although a bit off topic, looking back at my quality scans I did notice what might be a pattern. It appears to me that a burn when an initial Autostrategy strategy is first created is somewhat better than the next burn when AS is set to AUTO. Specifically, the first few MBytes in the former is clean with no PIFs, whereas in the latter the first few MBytes show high (though not awful) PIFs relative to the rest of the burn. This behavior was seen on both the TY T02 and MCC 004 burns. Maybe I’ll try with AS ON (or AS FORCED?) to see what happens. I suppose an alternative would be to clear the previously-created Autostrategy strategy before each burn – I am aware of the burn time price to be paid, but what I really want is the best end result without “do overs.” I’ve been embarassed in the past when, e.g., the school play video I burned (on other burners in the past) for friends skipped/froze in their DVD players.


#11

AS ON will use the strategy in the AS database if one exists, and only use the default firmware strategy if there is none. AS Forced will create a new strategy for each burn, but not save it in the database.


#12

Very helpful, thanks. Seems, then, that if my “theory” is correct, and a create-a-new-strategy-for-each-burn provides the best results, I would want to go with AS FORCED.

This whole topic is intriguing to me, and causes me to think that I ought to run a bunch of discs through the process with various settings to get a better handle than I have on what works best in practice. The matrix of AS and burn speed combinations and permutations is somewhat daunting, though, even with just two types of media, particularly when besides AS there are default strategies at each burn speed to also consider. Wives don’t appreciate seeing time spent on such things (I hear “You spent all that money and you have to do what???”)