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(PeteCresswell) 02-05-2013 01:15 AM

16x: Max Read Speed?
 
Am I wasting my time looking for a drive that will read the typical
commercially-produced DVD movie disc at more than 16x?
--
Pete Cresswell

Mike S. 02-06-2013 04:10 PM

Re: 16x: Max Read Speed?
 

In article <83n0h8926shambu1oifmlds351c8r3vlc2@4ax.com>,
(PeteCresswell) <x@y.Invalid> wrote:
>Am I wasting my time looking for a drive that will read the typical
>commercially-produced DVD movie disc at more than 16x?


You'd have better luck looking for a drive for which custom firmware is
available to avoid manufacturer-imposed limits on rip speed, etc.



(PeteCresswell) 02-06-2013 04:48 PM

Re: 16x: Max Read Speed?
 
Per Mike S.:
>
>You'd have better luck looking for a drive for which custom firmware is
>available to avoid manufacturer-imposed limits on rip speed, etc.


I might be up for that.

Could somebody elaborate?

Why would manufacturers impose limits on rip speed? To avoid excessive
errors?

Is there a significant increase to be had - like 50% ?
--
Pete Cresswell

Justin 02-06-2013 07:03 PM

Re: 16x: Max Read Speed?
 
(PeteCresswell) wrote on [Wed, 06 Feb 2013 11:48:39 -0500]:
> Per Mike S.:
>>
>>You'd have better luck looking for a drive for which custom firmware is
>>available to avoid manufacturer-imposed limits on rip speed, etc.

>
> I might be up for that.
>
> Could somebody elaborate?
>
> Why would manufacturers impose limits on rip speed? To avoid excessive
> errors?
>
> Is there a significant increase to be had - like 50% ?


Problems with vibration, owing to limits on achievable symmetry and strength in mass-produced media, mean that CD-ROM drive speeds have not massively increased since the late 1990s. Over 10 years later, commonly available drives vary between 24×(slimline and portable units, 10×spin speed) and 52×(typically CD- and read-only units, 21×spin speed), all using CAV to achieve their claimed "max" speeds, with 32×through 48×most common. Even so, these speeds can cause poor reading (drive error correction having become very sophisticated in response) and even shattering of poorly made or physically damaged media, with small cracks rapidly growing into catastrophic breakages when centripetally stressed at 10,000–13,000 rpm (i.e. 40–52×CAV). High rotational speeds also produce undesirable noise from disc vibration, rushing air and the spindle motor itself. Thankfully, most 21st-century drives allow forced low speed modes (by use of small utility programs) for the sake of safety, accurate reading or silence, and will automatically fall back if a large number of sequential read errors and retries are encountered.

Other methods of improving read speed were trialled such as using multiple optical beams, increasing throughput up to 72×with a 10×spin speed, but along with other technologies like 90~99 minute recordable media and "double density" recorders, their utility was nullified by the introduction of consumer DVDROM drives capable of consistent 36×CD-ROM speeds (4×DVD) or higher. Additionally, with a 700 MB CD-ROM fully readable in under 2½ minutes at 52×CAV, increases in actual data transfer rate are decreasingly influential on overall effective drive speed when taken into consideration with other factors such as loading/unloading, media recognition, spin up/down and random seek times, making for much decreased returns on development investment. A similar stratification effect has since been seen in DVD development where maximum speed has stabilised at 16×CAV (with exceptional cases between 18×and 22× and capacity at 4.3 and 8.5 GiB (single and dual layer), with higher speed and capacity needs instead being catered to by Blu-ray drives.



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