Digital Wanderer

We live as long as we fly

CD and DVD Media - Part 3, Practical

  So, in reality on DVD the following scheme is applied
A block of data is written, at the end of which there is information for integrity checking and error recovery. An error occurring inside such a block is called PI. (Parity Inner)  (The numbers in the picture mean nothing, they are just for beauty)
Data
Information for error correction within the block
{1 0 0 1 0 0 1 0}  {0 1 1 0}
    But what happens if there are so many errors in the block that they cannot be corrected using the redundant data at the end of the block itself? For this situation, after every 208 blocks, additional blocks are written with redundant data meant for correcting entire bad blocks that couldn't be fixed by the data at the end of the block. (I apologize for endlessly repeating the word Block, but then again I love him like the poet)
Data blocks
Information for error correction within the block  
Error block correction area

{1 0 0 1 0 0 1 0}   {0 1 1 0} 
{1 0 1 0 0 0 1 0}   {0 1 0 0}  
{1 0 1 0 1 0 1 0}   {0 1 0 1} 
{1 0 1 0 0 1 1 1}   {1 1 1 1}   . . . . .  etc. 208 times

{1 0 1 0 0 1 1 1}   {1 1 1 1}
{1 1 1 0 1 1 1 1}   {1 0 0 1}
{1 0 1 1 1 1 1 1}   {1 0 0 0}


  An uncorrectable error inside a block is called PIF (Parity Inner Failure) or PO (Parity Outer), and such a block is corrected entirely using the data marked in blue. However, if there are too many bad blocks, it's impossible to correct them, and the drive cannot read the disc, throwing a CRC Error message, which actually doesn't correspond to reality (for optical discs). It should be saying Unrecoverable PO errors. For us, the most interesting thing is that on Lite-On DVD drives you can check the error level using the Nero CD-DVD Speed or K-Probe programs. Drives from  Sony and some other brands - are also Lite-On). In Nero CD-DVD Speed, which is almost always included in the NERO suite, you have to select from the menu "Disc Quality Test" and set the speed to 4x, which is the standard for checking quality.
   So, up to a certain number of errors, the drive's microchip can correct them and continue reading. I won't give exact calculations and explanations here, I'll just say that for our purposes it's enough to know that the PI level displayed by the programs shouldn't stay above 280 for a long time,  and PO (PIF) - above 32. Isolated peaks don't count - they might be read or write glitches. But more or less long stretches will make the disc unreadable, although in practice a lot depends on the reading drive. Naturally, a lot also depends on the recording device. Plextor and Pioneer used to be famous, now cheap and high-quality-writing NECs are popular. Unfortunately, the saying "the Chukchi isn't a reader, the Chukchi is a writer"  works 100% here - it happens that NEC drives can't even read the discs they burned themselves (I mean the case of horribly low-quality discs). But blanks are crucial - even in the worst drive,  TY will most likely burn perfectly and be preserved for a very long time (excluding cases of incompatibility between the drive and discs, which happens)

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Lordi

Врубил запись Lordi с Евровидения  и кайфую. Как сказал мой друг: "Зарядимся положительной энергией - и к делу!"
Пошёл качаццо.

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Пиии

Сдох усилок от моих колонок.
Это пиздец.

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CD and DVD Blanks - Part 1, Economics

   Recently I wrote about how my Verbatim-made DVD blanks wouldn't read right after being burned.  It later turned out that many of them, which read fine during verification right after burning, stop reading a week or two later. Ultimately, I got incredibly pissed off and upset by the fact that I threw over $60 down the drain - what trust can you have in blanks, 1/3 of which become unreadable almost immediately?
  In the end I managed to talk my sister  mistrale1514 into buying and sending me for my birthday two 50-packs of the best blanks in the world - made by the Japanese company Taiyo Yuden. Oh, how much that sound means to the heart of someone in the know! The incredible quality of TY blanks has long since become a cult and a legend. Blanks better than these simply do not exist - except maybe KODAK CD blanks, back when they were still being produced, and rare specimens of HP.

   Next comes the story of why some blanks are better than others and how to figure it out. It isn't overloaded with technical details, so read on bravely if you're interested or just have nothing better to do.
  So, to start with, I'll briefly explain the basic economic tenets from the world of blanks. Optical media are produced by relatively few large corporations at their own factories. (Examples - Pprodisc, Mitsubishi Chemicals Corporation, CMC Magnetics Corp.) But in stores we see a huge number of different brand names. Why does this happen? The clever ones have already guessed that in blank manufacturing, as everywhere else these days, globalization reigns supreme, or more precisely its manifestation in the form of OEM production. Just like ghostwriters chained in a dark basement worked day and night, churning out novels published under the name of Dumas père, so hardworking Chinese and Taiwanese crank out tech gadgets that are then sold under cool brands like Sony, Philips, etc.
   This state of affairs suits everyone - the Chinese don't need much, and they get theirs through the sheer massive scale of production. Famous transnational corporations make a killing selling thin air in the form of their brands, and marking up the gadgets supplied to them by Asian manufacturers by 2-3 times. In return, they more or less control the quality, and the end consumer is perfectly happy, getting a merely decent product at a doubly inflated price.
  Taiyo Yuden is one of the prestigious OEM suppliers of CD/DVD blanks, whose services are used by titans like Sony and Plextor. Fortunately, Taiyo Yuden also sells blanks under its own brand, as many OEM manufacturers do.  Furthermore, unlike the Chinese and Taiwanese, TY doesn't play dirty games with the consumer. Let me explain what I mean.
 First of all, the quality of discs produced by the "Chinese" is highly inconsistent. For their partners - the big-name brands - they generally make excellent discs. For themselves (and their own brands) – of passable quality. And for crowds of obscure vendors – either bad, or really bad.
 Secondly, the quality can vary wildly from batch to batch, which is due to poor process control and using equipment way past the lifespan it was designed for. They set up new machines, calibrated them, checked the quality - the batch is spectacular. But a year or two later they forgot and stopped giving a damn - resulting in chunks of useless plastic  instead of optical media.
  Fourthly, discs from completely different manufacturers can hide under one and the same brand. And while in the case of reputable companies like Sony this isn't a big deal thanks to quality control, smaller companies that don't manufacture, but only sell discs, frequently change suppliers, which makes the quality completely unpredictable.
  Thirdly, discs produced at the factories of one and the same company, but in different countries, differ in quality like night and day. A classic example is Verbatim, under whose brand they actually sell discs from several different manufacturers. Verbatim itself usually manufactures discs at the factories of Mitsubishi Chemical Corporation (MCC), of which it is a part. But while the quality of the Singaporean factories is excellent, and the Taiwanese ones - acceptable, the Indians crank out the most atrocious garbage. What's more, the cunning Verbatim sells low-quality discs only in third-world markets. To our sorrow, in Verbatim's eyes the ex-USSR clearly falls into that category. Meanwhile, the US and Europe mostly get the cream of the crop. I  that time ended up with Made In India, and not Taiwan at all, which is so not very deservedly.
   So anyway - Taiyo Yuden is a Japanese company whose mind-blowing matrices (I'm definitely a robot) are sold under the names Sony, Plextor, and a few others. For example, Verbatim puts out the Verbatim Pastel series, which in reality are exactly  TY's products. See them at a good price - grab them without hesitating.
That concludes part one, the economic one.

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