Write strategy in case of buffer underrun?

vbimport

#1

I have noticed this with some other DVD-R drive. Does this happen also to The Plextor drives?

Here is the situation:
The drive lower the speed during recording (if buffer underrun occurs for 30 sec)? And the speed drops from 16x to 6x. The drive records disk with 6x speed till the end even the buffer underrun stops and data fills buffer constantly till the end of disk recording. Drive is not able to return recording speed to 16x which was set at the start of recording (this situation was found at Liteon SHW-16H5S and NEC-3500).

If anyone can help me with the answer. I’d like to know if Plextor drives (750 or 755) are able to resume recording speed back to the highest which was set at he start of recording (16x). Or they do the same (lower the speed to 6x and record disk to the with this speed)?


#2

you should probably be asking yourself why you’re having buffer underruns instead…


#3

Yep, the sticker on the dvd drive isn’t the problem with your system. You need to find out why your system isn’t providing data fast enough for the burner. There are many possible causes. Providing more information about your system, such as specs, settings, programs used, media type used will go a long way towards helping us help you.

The first thing I would check is if DMA is enabled on your drives.


#4

Buffer underrun is made artificially for testing purposes. But normally it can hapen when you access taskbar or open any program or do something else which needs access to a HDD from which image is burnt.

Don’t worry I don’t have buffer underruns when I don’t touch anything. In this case everything goes without problem and the disk is burnt with 16x speed all the way.

I feel like 5 or more years ago when there was no buffer underrun protection and we couldn’t do anything with PC while recorder was burning.

Take a look at this two graphs:
Recording at 8x
Recording at 16x


#5

Those don’t look like buffer underruns; they just look like the drives’ on-the-fly laser calibration/error checking systems dropping the speed to ensure a quality burn.


#6

Yes, they don’t look like it. But the truth is the point of droping speed is caused with buffer underrun. For me this looks like some kind of writing strategy. Drive lowers the speed to prevent low quality burning.

Weird is that nobody on the scene has mentioned this or noticed this. When I’m talking about this or asking around everybody is looking me as a ghost.

This situation happened with Liteon SHW-16H5S and NEC-3500. Now I’m trying to find out if this is the case also with Plextor. Because I’d like to get rid of droping speed and buy a new drive. People don’t help me a lot because they don’t know this problem. It looks they just burn and don’t care which speed drive uses.


#7

I dunno… there isn’t enough information provided for us to offer any suggestions.

In a previous post I asked for system specs, media type used etc. etc.

Showing two peformance graphs from Alcohol isn’t enough information. I have gathered that you are running either a dual core or HT P4, your system has 1GB of RAM and that’s it… Just based on that I would say use better media, but you may already be using good media.

People here do like to help others, we need you to give us the information asked for so we can assist you. This board can be a wonderful source of information and much can be learned here if you allow that to happen.


#8

My configuration:
Win 2000 SP4, P4 3.0 GHz, 1GB RAM, GF 6600GT, Maxtor 250GB PATA, Pioneer A-107, Liteon SHW-16H5S, NEC ND-3500AG…

All data defragmented, everything set to UDMA (not to PIO4), software for burning: Alcohol 120% latest, Nero 6.6.0.18…

My opinion is it’s not a problem in a configuration. Actually is not the problem at all. I think it’s jut the way it is. It’s the drives burning strategy. You should make this test on your drive and find out what happens on your computer. I’m sure same thing will happen.


#9

I’d like to discuss this situation with others. To see what are their experiences about this. Because it’s quite unknown thing. Everybody talks about the maximum performance in a perfect conditions. And all tests are made that way. But conditions in a regular PC are far away from perfect.


#10

AFAIK the drive uses the BURN-Proof technology in the process of testing writing quality. So only after having stopped writing (with BURN-Proof) it is possible to detect that quality has become worse and that a lower writing speed would be advisable.


#11

I know this feature. It’s called diferrent ways at different manufacturers. If turned on happens exactly what you said.

But im my case it’s not the point in a bad quality of media or burning. It’s about lowering the speed just because of buffer underrun. I can’t understand why this happens.


#12

I would agree with you that your configuration doesn’t appear to be the problem. You have enough hardware, and with DMA enabled sustained transfer rates should allow you to burn at 16x.

Media codes still have not been provided so I can only assume (hate using that word) that you are using garbage media. Another possibility is that you are using good media and that the firmware in your drive does not have a write strategy for it. That doesn’t seem likely, as the norm is to write at slower speeds with unknown media.

I don’t need to perform any tests on my system… I can write at 16x speeds without speed drops, I prefer to write at 12x for quality reasons.

Good luck finding resolution to your problem.


#13

When dropping speed Buffer Underrun will always kick in for a short time to ensure that writing is going on with lower speed just from the point where problems werde detected not when disc will spin down 10 seconds later. This is perfectly normal behaviour.


#14

Brokenbuga, try to make artificial buffer underrun while burning. Just for 30 sec or 1min. Then you will se if you are still able to write with 16x speed. By my opinion, no.

You asked. I use Verbatim and MCC media. I never use garbagge. Droping speed happens no matter which media I use. It’s not dependable of media. I also tryed with Maxell, Ritek, Prodisc, Ricoh… Every time the same story.


#15

@ Aleksander69

In reading your previous posts, I’ve seen that you have started numerous threads, all asking the same question you are asking here. In each thread, people have responded and have tried to be helpful, yet you still want to debate. I’m not entirely sure what it is you are trying to accomplish, and as such I can not help any further.

I wish you the best of luck in finding resolution to whatever it is you are after.


#16

Brokenbuga, with all respect to you!

Hm. It’s obvious that some people didn’t understand what I would actually like. I’m very grateful for a help which all of you offered. BUT!!! I would more like something else. Like you have noticed a debate about this situation. My opinion is that my problem is also the problem of all who have same recorder (Liteon SHW-16H5S). And what I would like is that people would give me just an information if the same thing happens also with their recorder. Because I could be WRONG. Maybe All this is happening to me only.

About numerous threads. I’m asking same question in Plextor forum because I’d like find out if same situation happens with Plextor drives. I don’t have chance to test it by my self that’s why I’m asking people to make a simple test and post reply. I’m interested in buying Plextor drive but first I’d like to find out if this drive (750 or 755) is able to record disk without lowering speed if buffer underrun occurs.

It’s a simple question, isn’t it?


#17

Yesterday I had chance to test Plextor 716. I made the same thest which I was talking about in a previous posts. And the same happend with Plextor drive also. The drive dropped the speed to 6x and wasn’t resume burning with 16x speed after buffer underrun stopped.

I must say thest was made in a Nero with Powerrec turned off. There was no test made with Power rec turned off with Plextools. I will try to do this also and si if there is any difference.

“The buffer underrun proof technologies offer a solution to prevent writing failures during the burning process for CD and DVD by pausing the burn if the data to the drive write buffer is slowed or stopped. The drive resumes the burn process after the drive write buffer is refilled.” This is written on a Plextor web side which explains how buffer underrun works. But it is not true completelly. Drive is really able to resume recording. But not with the same speed which was set at the start. It only records with aa 6x speed!!!


#18

Still noone has any experience with this situation? Didn’t anyone try to check this??? Are all of you satisfied with 6x speed??? I’m not!!!


#19

i know i never have to deal with buffer underruns of that extent…and i burn while browsing, watching video and having azureus hog 100+MB of my RAM…

not sure what you expect from others here, but i suspect not many of us burn under the conditions you’ve outline previously and/or don’t run into buffer underruns as extreme as you do…and/or don’t care :eek:


#20

DRPINO

I’m sure you are doing many things while burning. But did you ever check the time or speed after burn is complete? And try to burn some image from the system drive where OS is placed and all your programs. I’m sure your drive will drop speed during burning.

I wrote clearly what I expect. Just to post some resulsts and experiences from other people. and see if other people have same situation as I. I know we will not solve this problem because it’s not possible to do it.

Sure most of the people burn and don’t tuch. In this case it,s not possible to have buffer underruns. And of course if you don’t care you don’t have trouble. But I care a lot. Because I bought 16x drive and I’d like to burn with 16x not with 6x. I’m sure there are also some people which would be unsatisfied with their drive if they would know about what is happening.

One more thing. Manufacturers are selling us a lot of features to make their drive better. One is that drive is able to stop burning and waiting for data and then continue burning if buffer underrun happens. Partially it’s true but not completelly. Drive is really able to stop and continue. But not to continue with higher speed but only with 6x speed. This is what I would like to tell to the people and talk about. Why the drive isn’t able to continue with 16x times speed? Noone gave me the answer yet.