[Zigfeld]

I have had two recordings, about 2 hrs in length, that around half way through the playback, it started to pixilate and sputter for the remainder of the program. Is this a dirty disc, a bad disc, or a problem with the recorder?


Thanks.

 

[vferrari]

Symptoms indicate that it's probably a bad disc (when the disc properties/dimensions change due to temperature during either recording or playback you can get the described problems. It can take about an hour to reach the temperature that starts to cause the problems, hence you see it about halfway through a two hour recording). But it would help if you posted some info about the recorder you are using and the type and brand of media you are recording to. Otherwise we are just shooting in the dark trying help you.

 

[Zigfeld]

Thanks for your response. I have a JVC DRM10s. I believe in this case I used a Panasonic RAM disc. I will try a different disc (purchased as a 5 pk).


Another question with discs; when viewing a prerecorded movie, (Blockbuster). I just watched one that the playback froze up on 2 or 3 spots during the movie. Had to stop the playback and advance to the next chapter to continue. The disc looks scratched and worn. It did play in another DVD player with only one glitch. Just a damaged disc?

 

[vferrari]

I 've never encountered such a serious error with a RAM disc unless it was visibly damaged. If it has no visible scratches I would suspect the recorder as well. As far as the Blockbuster discs are concerned, yeah they are usually pretty beat up and dirty, so that's probably the reason. Many people who own high end gear either refuse flat out to put these discs in their quality players or take great pains to thoroughly clean the discs before use.

 

[Jay Davis]

Sorry, but read the threads on JVC DVD recorders. They have too many problems and such a poor customer service and repair reputation that many owners have scratched them off their buy list. Also note, that the big 4 of Sony, Pioneer, Panasonic and Toshiba have their own problems too. It's enough to scare you back to VHS.


I no longer rent movies. Up until recently I would occasionly pick up used DVD's from Blockbuster. I clean and Disc Doctor them before playing. I return any disc that still freezes up. I say 'up until recently' because I no longer buy used discs either. Too many problems which as vferrari eludes too may damage your player.

 

[Church AV Guy]

Quote:

Originally Posted by Zigfeld Thanks for your response. I have a JVC DRM10s. I believe in this case I used a Panasonic RAM disc. I will try a different disc (purchased as a 5 pk).

I had the exact same thing happen to one of my Panasonic RAM disks a while back. There was no visible sign of damage, but the recordings just pixilated and sputtered for a time, and then settled down again. I messed with the disk for a while, but it became clear that it was damaged in some way, and after reading how these recorders respond very badly to damaged disks, I just tossed it. I did not want it to get stuck inside the machine!


I was using one of my Panasonic EH50s.

 

[jpurkey]

Dust on a DVD-RAM disc can cause such problems. If the error occurs during the recording then cleaning the disc would not improve playback. However, cleaning the disc would mean that future recordings & playback should be fine.


I had the dust problem with DVD-RAM discs a few times before I switched to the cartridges. The cartridges have a protective shutter that prevents dust from getting inside. I've been using some DVD-RAM cartridges for several months now without a single problem.

 

[Church AV Guy]

I have been using some for months without problems too, BUT just this one disk is damaged. There is no dust, smudge or fingerprint on it. It's just not working. Anyone know where to return it for a replacement? It came in a package of ten, but only one was bad. It's not very important to me though, because I recently bought some 5X -RAM disks and I use them mostly now. I doubt I'll miss that bad 3X one.

 

[Church AV Guy]

Well this is an odd one. Last night I examined the "bad" ram disk with a magnifying glass and found nothing that would account for the pixilation and drop outs. The surface looked perfect. I read in a thread here that someone else had a disk with this problem, so he cleaned it and it started to work again. Well, I decided, nothing ventured, nothing gained, so I carefully washed the disk with mild detergent and a cotton ball. I dried it with a soft tissue (without aloe, and with my wife its hard to find a tissue without aloe) and put it into one of my recorders and filled it up. There were no problems this time.


How weird is that? Was something on the surface of the disk that I couldn't see but interfered with the laser? I'm at a loss, but the disk now works.

 

[jpurkey]

I would still bet my money on dust causing a problem with the recording. It was probably just gone by the time you inspected the disc.


With the non-catridge DVD-RAM it is always a good idea to take a quick glance at the disc before inserting it to see that it is clean. Fine dust doesn't seem to be a problem, it is the larger/easily visible pieces that can cause write errors. And even once the disc is clean you'll continue to get the error during playback until you record over that section again.

 

[rgazzara]

Quote:

Originally Posted by jpurkey I would still bet my money on dust causing a problem with the recording. It was probably just gone by the time you inspected the disc. With the non-catridge DVD-RAM it is always a good idea to take a quick glance at the disc before inserting it to see that it is clean. Fine dust doesn't seem to be a problem, it is the larger/easily visible pieces that can cause write errors. And even once the disc is clean you'll continue to get the error during playback until you record over that section again.

Is dust more of a problem with the DVD-RAM disks that it is with other DVD disks? In other words are you saying the we need to be more careful about dust on DVD-RAM disks than on, say, DVD-R/W disks?


RG

 

[Sean Nelson]

Quote:

Originally Posted by rgazzara Is dust more of a problem with the DVD-RAM disks that it is with other DVD disks? In other words are you saying the we need to be more careful about dust on DVD-RAM disks than on, say, DVD-R/W disks?

This is actually a very good question. CDs and DVDs use quite sophisticated ECC (Error Checking and Correction) codes which can recover the data if it's not readable. What's particularly interesting about these codes is that they're distributed along a track so that the data and the codes that protect it are far apart (ie, 180 degrees around the disc track). This reduces the chance that a flaw in a particular spot on the disc will affect both the data and the ECC codes, thus improving the chance of being able to read the data even when the disc is scratched or abraded.


DVD-RAM, on the other hand, records data in relatively short sectors on the disc. You can actually see the sector boundaries stamped into the disc. I'm guessing that the data and the ECC info for that data all have to go together into the same sector. If that's true then it could mean that problems with the disc might have a higher chance of causing an unrecoverable error than for a DVD or CD.


This difference in design is necessary because DVD-RAM is designed to be "block replaceable" (ie, you can overwrite the data in any one block or sector without affecting the adjacent blocks), whereas writeable CDs/DVDs can only accept large quantities of data recorded all at once in "sessions".


It would be interesting to hear from someone with more than speculative information on the subject...

 

[rgazzara]

Sean,


Good analysis and very interesting.


Do others have any ideas?


RG

 

[jpurkey]

Quote:

Originally Posted by rgazzara Is dust more of a problem with the DVD-RAM disks that it is with other DVD disks? In other words are you saying the we need to be more careful about dust on DVD-RAM disks than on, say, DVD-R/W disks?

I'm not sure, but you can get the DVD-RAM discs in cartridges and since switching to the cartridges I haven't had a single problem.


If you are going to use DVD-RAM for time-shifting then I would recommend buying some cartridges. Get the doubled sided type if you can. You do have to flip them to use the other side, but it's more convienent than using two discs, especially if you don't keep your discs stored within easy reach.

 

[Church AV Guy]

While I don't doubt that you have had no problems since switching to cartridge type -RAM disks, was the switch such an improvement? I have close to fifty -RAM disks, and so far I have had one disk with a problem. It was consistent as to where the problem was on the disk, and since I cleaned the disk, that problem has gone away. I'm not sure that there is too much room for improvement. With the exception of that one disk, all my non cartridge -RAM disks have been perfect. The cartridge disks are more expensive aren't they?