24x DVD write speed - why not 24x read?

I don’t understand why the latest drives (AD-7240s) can achieve 24x DVD write speed, but they are still stuck at 16x read speed! :rolleyes:
Any explanations? :confused:

The reason is Marketing.

The “x” number is used for marketing purposes and if a drive can write a single type of DVD at 24x, then the claim can be said to be true. The drive doesn’t have to be able to read anything at 24x in order to claim “24x” in a big font on the box of a retail DVD burner.

Drive manufacturers think that only the drives with the highest “x” numbers will be able to sell, since the public wants what’s “best” and the highest “x” number must obviously be better than a lower “x” number. They are probably mostly right in thinking so, which is a shame.

Of course, I agree, but isn’t a plus to be able to read also @ 24x? :wink:

Let me rephrase my question: is there any technical constraint which prevents reading @ 24x? :slight_smile: (I don’t think so, since writing @ 24x is feasible…)

[quote=bedazzled;2260897]Of course, I agree, but isn’t a plus to be able to read also @ 24x? :wink:

Let me rephrase my question: is there any technical constraint which prevents reading @ 24x? :slight_smile: (I don’t think so, since writing @ 24x is feasible…)[/quote]
This burner and any other burner will only be able to burn at 24X with very few media codes. This can be very misleading, there is no 24X media for sale anyplace in the world. Taiyo Yuden 16X media and Verbatim media may be the only media able to reach these unneeded speeds. So I find it a little misleading advertising 24X burner without mentioning it will only attain these speeds with few medias.

…and with those very few codes that can be written at 24x [even the Verbatim/MCC/MKM codes have only officially been allowed up to 20x on one of the 24x drives, so far as I’ve seen!], not even all the discs from each of those disc models are mechanically sound for being written at 24x; only the best batches perform well with 24x writing.

Thus, the list of discs that would be mechanically sound and easily READ at 24x, without actually taking MORE time than a stable read speed of 18x [the official maximum read speed of a few DVD-ROMs and one of the best unofficially supported overspeeds on newer Samsung and LiteOn DVDRW drives], is slim.

You’d think that reading would be easier than writing, but refer back to Samsung’s 18x drives, and some of LiteOn’s earlier 20x drives, that could not read at 18x with a consistent stability, and could not always do DL media at 12x read speeds.

@[B][B]alan1476[/B]
[/B]I am aware of that fact… and obviously 24x is achieved at the very end of the disc (P-CAV), I am not that noob.[B] :stuck_out_tongue:

@[/B][I][I]Albert[/I]
[/I]I’ve seen a few scans from 24x written discs and they seem perfect (OK, nobody knows what is gonna happen after 1-2-3-5 years, maybe there is a catch/side effect of deteriorating faster, who knows… :o)

And yes, I think reading is easier than writing… what do you mean by [I]"[/I]mechanically sound"? Is there a danger of the disc breaking?
It reminds me of the 52x CD era (and even 54-56x if I remember correctly), a lot of drives caused discs to break… they need about ~12000 RPM to achieve these speeds I think…

[QUOTE=bedazzled;2260936]what do you mean by [I]"[/I]mechanically sound"? Is there a danger of the disc breaking?[/QUOTE]I’m not necessarily saying the discs will break. I am, however, saying that different disc models will be made to different thickness, and not all discs will be of an even thickness. There may be issues with discs warping at high speeds/certain RPMs, and some discs just don’t have a great balance. For these discs, if they could be read at 24x, I’d imagine that they’d make a great deal of noise [something most consumers don’t look for], or would require a new drive pick-up mechanism [designers would have to make a new pick-up mechanism to compensate for poor balance].

Still other discs are physically crippled, but in a more minuscule way. For example, a B-grade 16x rated disc may only be written well at a lower speed, like 12x or 8x or even lower sometimes, and the physical problems with these low-quality media will also require a lower read speed. [The physical problems may cause tracking errors, focus errors, etc]. I’d imagine that very few discs have been machined to a level of quality at which the drives can keep a proper tracking and focus at the 24x RPM to the outer edge of the disc, even if the disc had been written to the best possible quality.

There may still be the issue of a poorly designed/machined/bonded disc becoming unreliable at the 24x RPM and breaking, but I don’t see that as being too much of an issue.

If 24x reading was supported, it would likely be on a per-disc model basis, probably only supporting the same media as is supported for 24x writing.

I could see 18x reading being incorporated, but the promise of reading discs at 24 speed seems about as useless as writing discs at 24 speed; too many discs would just fail to be read stably at that speed.

It’s perhaps very straight forward why 16x is max read speed.
When writing at 24x the drive use AOPC. If it has problems it will slow the burn down, to cope with the media. When reading, it doesn’t have this, and would probably just fail with an error.

I would also presume that the industry is not too keen on you being able to rip discs at 24x! That said, I think Dee is right about AOPC – although I recall some BenQ drives inadvertently using WOPC on ripping and having speed drops on CD Speed scans as result every gigabyte or so (with certain firmwares). I guess if BenQ can make that work, so can everyone else.

The thickness must be 1.2mm (with a tolerance of ±10%?), that’s what the standards say at least… or else it won’t get the certification for CD/DVD/BD/whatever (I remember some dual-mode CD+DVD-Audio discs in the past which were 1.5mm thick and Pioneer warned the customers that they may not be read well…)

http://www.google.com/search?q=dvd-audio+1.5mm

Not an issue, there’s already AD-7240s and according to marketing (and NEC’s good reputation of course), consumers will embrace it…

That would be a fair deal I think. :slight_smile: For example AD-7240s + TYG03 media…

[quote=Dee-27;2260973]It’s perhaps very straight forward why 16x is max read speed.
When writing at 24x the drive use AOPC. If it has problems it will slow the burn down, to cope with the media. When reading, it doesn’t have this, and would probably just fail with an error.[/quote]
Isn’t it technically feasible to use AOPC in reading also? It could slow down if there is a problem…

[QUOTE=bedazzled;2261013]Isn’t it technically feasible to use AOPC in reading also? It could slow down if there is a problem…[/QUOTE]Probably, in fact, NEC chipset drives are excellent for TRT tests, as the drive will [B]slow[/B] if its having difficulty in reading a disc. but at 24x speed, it wouldn’t be given much of a chance to slow down, more than likely, it would just fail with an error. I recall C0deKing tried some experimental firmware on Lite-On drives (reading @18x) and i seem to remember there were problems with those drives as well.

…but poorly made discs will have uneven thickness over the surface of the disc, and while its average may be 1.2mm ±10% (as you have mentioned), there is no guarantee that it is perfectly at that thickness every time. :frowning:

…but they don’t know that it’s only limited to certain media. I also haven’t heard of some new-fangled way to balance those discs, and the price of the 7240 suggests that it uses similar components of earlier 22x writers. Marketing… :rolleyes:

…but not everyone has premium TY 16x media… :sad:

[QUOTE=bedazzled;2261013]Isn’t it technically feasible to use AOPC in reading also? It could slow down if there is a problem…[/QUOTE]

It is technically feasible, but if the firmware/chipset is too limited to allow more advanced programming (BenQ has those great Nexperia chipsets), no amount of programming will make it happen. Drives slow down normally when they encounter a problem with the disc, but most revert to a slower speed after that point.

As much as I’d like to have a 24x read speed, do drives have such a detection feature that selectively allows it to read at 24x (for certain discs only) like how it does when in the procedure of writing? :confused: I wouldn’t want a 24x read if it will only kill my drive (and shatter my discs) inadvertently.

[QUOTE=evo69;2261029]As much as I’d like to have a 24x read speed, do drives have such a detection feature that selectively allows it to read at 24x (for certain discs only) like how it does when in the procedure of writing? :confused: I wouldn’t want a 24x read if it will only kill my drive (and shatter my discs) inadvertently.[/QUOTE]NEC chipsets have this feature. Pioneer use it on their drives, where certain media is restricted to lower reading speeds. The problem most likely would be, that the chipset is only designed for reading at 16x max, so higher speeds are technically not possible anyway.
But i can only guess this. :slight_smile:

I wouldn’t want that too.
I guess that must be the explanation. There are more chances breaking a WORM disc while reading it, rather than writing it (you do that only once after all, statistics)…

Isn’t it strange that we had 52x CD burners 6-7 years ago, but now we are limited @ 48x? :wink:
Maybe it’s the same case, not a coincidence…

[QUOTE=bedazzled;2261038]I wouldn’t want that too.
I guess that must be the explanation. There are more chances breaking a WORM disc while reading it, rather than writing it (you do that only once after all, statistics)…

Isn’t it strange that we had 52x CD burners 6-7 years ago, but now we are limited @ 48x? :wink:
Maybe it’s the same case, not a coincidence…[/QUOTE]

Reading was also limited, i remember the 48/24/48 plextor was limiting the read speed to 40x, if you wanted 48x you had to keep pressing the eject button for 2-3 seconds.

[QUOTE=bedazzled;2261038]
Isn’t it strange that we had 52x CD burners 6-7 years ago, but now we are limited @ 48x? :wink:
Maybe it’s the same case, not a coincidence…[/QUOTE]

Yeah, that underlines that marketing theory!!!

Its sadly all about marketing BS this time.
What comes next?

I see absolutely no sense for 24x or 20x dvd burning - 16x is enough or maybe even 18x with TOP media. That few seconds will not make the fish fly… :bigsmile:

[QUOTE=bedazzled;2260809]I don’t understand why the latest drives (AD-7240s) can achieve 24x DVD write speed, but they are still stuck at 16x read speed! :rolleyes:
Any explanations? :confused:[/QUOTE]

goodmorning chap. this has always been my question too. if writing at high speeds is achieved(which i think is more complicated procedure than read) why not high speed read? there was a mate in here who answered me in the liteon forum. he said that different variables happen during read and writing and though reading may sound more simple than writing, in fact it isn’t. i am sure that there will be the time that a company will advertise a 26x dvd recording with 26x reading capability. at least to the media that supports 26x.

[QUOTE=Dee-27;2261028]Probably, in fact, NEC chipset drives are excellent for TRT tests, as the drive will [B]slow[/B] if its having difficulty in reading a disc. but at 24x speed, it wouldn’t be given much of a chance to slow down, more than likely, it would just fail with an error. I recall C0deKing tried some experimental firmware on Lite-On drives (reading @18x) and i seem to remember there were problems with those drives as well.[/QUOTE]
The LiteOn 20A3 reads perfectly at 18x and the iHAS series up to 20x. I haven’t tried any faster than 20x yet. The current patched FR firmware for the A3 and iHAS drives allows 18x reading, as a compromise for speed and safety, and has no problems.

LiteOn also recently released a DVD-ROM drive that reads SL ROM media at 18x but everything else is 8x or less.

I agree that the burn speed looks good on the box. When they can’t make them burn any faster they will start increasing the read speed. :iagree:

[QUOTE=vroom;2261191]Reading was also limited, i remember the 48/24/48 plextor was limiting the read speed to 40x, if you wanted 48x you had to keep pressing the eject button for 2-3 seconds.[/QUOTE]
48/24/48 drives were the previous generation from 52/32/52 ones. :wink:
And there were even 54/32/54 and 56/32/56 models! :eek:

[QUOTE=GDRIVER;2261217]i am sure that there will be the time that a company will advertise a 26x dvd recording with 26x reading capability. at least to the media that supports 26x.[/QUOTE]
26x is too much, even for writing, 24x must be the upper limit for DVDs, just like Blu-Rays will reach a maximum @ 12x…

Well, the media to be burned at 24x are mainly/solely Jap TY which are new and usually in pristine condition ie. predictable controlled conditions. Media to be read can be in any condition, from new to badly scratched rentals so it may be futile trying to read them at too fast a speed. It may just cause the motor to spin up and down resulting in even longer read times.

I actually had a 6.2x DVS DVDROM (cheap Korean make, 6.2x is faster than plain 6x you know :bigsmile: ) which burned out spinning up and down trying to install a borrowed kiddie game ie. it never gave up reading what must have been a bad disc.