Regarding "gold", there is no magical metallization, dye, or brand, just
effort. Careful selection of media, writer, and reader will provide results
that are competitive with other forms of mass storage with the exception of
Playback of every CD or DVD disc generates hundreds of thousands of errors.
These are detected and corrected at multiple levels in the read drive. The
first level handles the easy ones, while more serious ones are passed along
to higher levels.
Regarding playback, you are correct about the importance of read drive
quality. This is often overlooked. All CD discs have two powerful levels of
error detection correction that can flawlessly read a disc containing a one
mm hole. CD-ROM discs have an additional level that expands error detection
and correction capabilities. DVD discs utilize a powerful product code that
conducts error detection and correction in two passes.
Read drives generally differ in the characteristics of their servos that
maintain precise axial focus and radial tracking of the read laser. Errors
are generated when a defect, such as dust or a scratch causes either of
these to temporarily unlock, and errors then continue until the defect
passes by and the servo relocks.
An excellent read drive may flawlessly read through a defect. A normal read
drive may generate a few correctable errors. A poor quality read drive may
fail to successfully read the disc. CD-DA (Digital Audio) discs that lack a
third level of error correction may utilize methods such as interpolation or
muting in an attempt to conceal uncorrectable errors, but the results may be
detectable by a careful listener.
All methods of digital archiving require careful selection of media, writer,
and reader along with good handling and storage procedures.
Media Sciences, Inc.
> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
> Sent: Friday, November 12, 2010 3:04 AM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] Falcon Optical Media
> I don't post much here, but have been reading posts here for about 6
> months. My focus is on audio and video preservation. We (AMIPA) only
> use CDs and DVDs as access media - NOT for preservation. We have had
> problems with "Gold" DVDs as they are often unplayable on players in
> computers, though I've never seen one fail to play in our dedicate DVD
> player. I can't help but wonder if Corey's observations might be tied
> to the ability of his playback device to correctly read all of the data
> from "Gold" CDs? Could it be that the playback device is compensating
> for data it can't retrieve and thus dropping or reinterpreting part of
> the spectrum using it's own software? I'm not an expert when it comes
> to digital playback. Many digital playback devices we are using now
> "impose" themselves via hardware based software on our data. The data
> stream coming out of one device will often not match bit-for-bit the
> data stream from another device that reads from the same media. That is
> certainly the case with DV video (and other digital formats) where the
> playback device massages the raw data from the tape (concealment is the
> example I've most often seen used when discussing DV). This all gets
> really messy. So to keep it short - I wonder if the problem Corey noted
> is with the media or with the playback device he used?
> --greg schmitz
> Alaska Moving Image Association
> Anchorage Alaska
> On 2010-11-11 2:00 AM, Tom Fine wrote:
> > For what it's worth, I have found that blue-dye silver discs, I prefer
> > Toyo-Yuden just because I have years of good experiences (successful
> > burns, near-universal playability), seem to work best as playback
> > media. In fussy car players, in old home players, in early DVD
> > players, etc. I also have heard similar things to what Corey heard in
> > a gold MAM vs. a blue-dye T-Y, played back in a mid-90's vintage
> > Philips CD player. Played back via my Tascam CD recorder, I couldn't
> > hear any difference. I am guessing that older CD players have trouble
> > reading the gold-backed CDs and thus either more error correction is
> > going on or for some reason jitter is being induced, or some other
> > digital-realm thing is going on. My conclusion was to pursue the same
> > recommendations as Corey -- blue-dye/silver for playback, gold-back
> > for archiving (although I highly recommend a maintained hard-drive
> > archiving strategy).
> > -- Tom Fine