What is the MiniDisc (MD) and What is the difference between the 60,74 and 80 min of MD?

The creation of the MiniDisc MD

MiniDiscs were announced in 1991 by Sony as a disc based digital medium for recording and distributing consumer audio that is “near CD” in quality.

In 1993 Sony announced MD Data, a version of the MiniDisc for storing computer data.

There are two physically distinct types of discs: Pre-mastered MDs, similar to CDs in operation and manufacture, and Recordable MDs, which can be recorded on repeatedly and employ magneto-optical technology. The disc itself is enclosed in a small (7cm x 7cm), convenient, cartridge.

Nearly 160MB for 74 min. in audio mode [140MB in Data Mode]

What is the difference between the 60,74 and 80 min of MD?

The pregroove wobble is at a higher linear frequency (cycles/cm.) on the 74 minute blanks, causing the recorder to spin the disc slower (74 min: 1.2 m/s vs. 60 min: 1.4 m/s) and thereby record more information in the same linear space.

The 80 minute discs are made by decreasing the track pitch (i.e. space between tracks) from the MD standard’s 1.6um to 1.5um (micrometers), the minimum allowed by the MD specification; like the 74′ blanks, they also run at 1.2 m/s.

There is also information encoded in the read-only TOC near the inner circumference of the disc telling the player how long the disc is.

What is a Disc master? How to make a good Master stamper?

The Manufacturing Process

The process of manufacturing a CD, DVD or Blu-ray begins with a data disc master. A data master (also known as disc master) has the program (either digital CD audio or computer files) as it will be on the manufactured disc.

This disc master is used to make a stamper (typically a nickel alloy) that has the inverted pattern of pits and lands, which contain the data. This stamper is attached to one side of a split-cavity mold.

Molten polycarbonate is squeezed into the mold at precise speed and pressure, then cooled. As the polycarbonate cools, additional pressure is placed on it by the mold cavity, pressing the pattern of pits and lands into the top-surface of the disc.

For a good data disc master:

  • Check, double-check, and triple-check your files! Once a stamper is made, it cannot be changed. If you find errors after the stamper is made, a new stamper will have to be made!
  • Use standard file formats for data discs. Avoid using exotic or proprietary files formats where possible to promote end-customer satisfaction.
  • Burn data disc masters to high quality recordable media using DAO (Disc-At-Once) write mode ONLY. Do NOT use TAO (Track-At-Once) or SAO (Session-At-Once) modes. Although a stamper can be prepared from these, it requires additional processing and prevents bit-to-bit comparison of the replicas to the data disc master. A good alternative is to use a disc image in a standard format (DDP, ISO (DVD or data CD), or BIN/CUE (CD Audio) stored on removable media such as flash drives or cards (a DDP image is, in fact, ideal.) Checksums can be made to ensure data integrity.
  • If using recordable media masters, ensure that the write session is “closed” when completed.
  • Normalize audio tracks before mastering.
  • Check your DVD menus thoroughly to ensure that they are easy to navigate and work properly.
  • Try to keep CDs to less than 650 MB (74 minutes of audio) and DVDs to less than 4.7Gb (DVD5) or 8.5Gb (DVD9).
  • Although modern recordable media sometimes have much higher capacities, the ISO standards were written for the above capacities. Discs exceeding these recommended sizes may not conform to readability standards and consequently, may have slight to severe readability issues.
  • If distributing .pdf formatted files, it is recommended to include the freely distributable Adobe Acrobat reader so that end-customers can install it if they do not have a .pdf reader. Freely distributable readers for most other file formats exist as well and should be considered for inclusion where appropriate, especially if unusual or proprietary file formats are used.
  • Check your data again, you can never be too certain.

Explaining the process of manufacturing a CD or a DVD

Step-by-Step Guide To CD Manufacturing

The process of making a CD begins with a data master. A data master has the program (either digital CD audio or computer files) as it will be on the manufactured disc.

This master is used to make a stamper (typically a nickel alloy) that has the inverted pattern of pits and lands, which contain the data. This stamper is attached to one side of a split-cavity mold.

Molten polycarbonate is squeezed into the mold at precise speed and pressure, then cooled. As the polycarbonate cools, additional pressure is placed on it by the mold cavity, pressing the pattern of pits and lands into the top-surface of the disc.

The clear polycarbonate disc is then cooled until it is firm enough to hold its shape and then sent down a cooling tunnel to a metallizer. In the metallizer, a micro-thin layer of aluminum, just thick enough to be fully reflective to red laser light is deposited on the disc by a process known as sputtering.

The disc is then coated in a thin layer of lacquer and spun at high speed to smooth the lacquer. The lacquer protects the fragile aluminum coating from physical damage such as scratches and from oxidation. The lacquer is flash-cured under intense UV light and then taken to a separate machine to have the label printed.

CD Replication Machine - Data Verification Stage
CD Replication Machine – Data Verification Stage

Step-by-Step Guide To DVD Manufacturing

Like CDs, the making of a DVD begins with a data master. DVD data masters are somewhat different, because DVDs can have up to two sides, and up to two layers on each side, so the DVD data master can be as many as four separate discs.

There are many formats for DVDs, but the most common are DVD5 and DVD9. DVD9 has one side and two layers of data, so must have two stampers made, one for each layer.

The stampers are loaded into two molders. Each molder will press a “half-disc”, one for the top, and one for the bottom, each with data. The two halves are moved separately to metallizers. The metallizer for the top half will deposit a fully reflective aluminum layer similar to a CD (though on the bottom side of the half-disc).

The metallizer for the bottom half-disc deposits a semi-transparent layer on the top-side of the half-disc. Lacquer is applied to the bottom half-disc, then the top half-disc is put on top. Air is squeezed out as the two halves are spun together.

When the lacquer is flash-cured in a process similar to that for CDs, the two half-discs are permanently bonded together. When a DVD9 is read, the laser must shift focus between the two layers in order to read from one or the other.

For this reason, the thickness of the lacquer bonding layer must be very tightly controlled. A DVD5 is made in a similar way, but the bottom half-disc is fully reflective, and the top half-disc is (usually) left clear.

Understanding Blu-ray Replication Vs. Duplication

Blu-ray Replication

Blu-Ray replication is the process which most Blu-ray disks (BDs) are made. Replication involves making a glass master from the digital audio, video, or data that will be on the disk.

This glass master has the shape of the pits and lands that are used to store the data on the disk. The glass master is used to make a metal stamper, which is a negative image of the BD.

The stamper is used as part of an injection molding machine to impress the shape into liquid polycarbonate as it cools inside the mold in a process called “coining”.

The polycarbonate disk is then coated in aluminum in a process called sputtering to reflect the laser beam of the reader so the disk can be read. The disk is then coated in lacquer to protect the data from scratches and oxygen.

If the BD is multi-layered, the other layers will be embossed into the lacquer which will then be sputtered with a semi-transparent layer of aluminum, then coated in lacquer again.

This process is repeated for each layer of data. A second type of lacquer (TDK® Super Hard Coat) is applied last to give it extra scratch resistance.

The BD is made to extremely tight tolerances for flatness, and this includes the lacquer layers. Then, finally, the BD is printed with a label. BD replication is the most efficient way to make a large number of identical BDs. The BDs produced by replication last much longer than duplicated disks.

Blu-ray Duplication

Blu-Ray disks may be duplicated by “burning” a copy of the information from one Blu-ray disk (BD) onto a recordable BD (BD-R). A laser in the recorder melts a pattern into the recordable disk that mimics the pattern of pits and lands found on a replicated BD.

BD duplication is good for making a small number of copies of a disk, but is not well suited to making large batches of BDs. Duplicated BDs do not last as long as replicated BDs, and are more prone to be damaged by things like sunlight or heat.

How Can a USB Flash Drive Be Used As a Promotional Tool?

Custom Swivel USB Flash Drives
How Custom USB Flash Drives can be used in promoting your business:

  • A Custom USB flash drive can promote your company by your customers using them and spreading your corporate identity everywhere they go. Using such an office friendly device is a constant reminder that they have received from you one of the most value-added devices that will be in marketplace circulation.
  • A branded partitioned Custom USB flash drive can be the promoter of your company by your customers using them and also containing valuable content. This content can be: PDFs, a company catalog (PDF or eBook), a company video, or an assortment of documents. This is definite intrinsic value that spreads your corporate image everywhere they go in the marketplace. This is also a value-added device that is a constant reminder because of the content.

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Custom USB Drive Design AreaFor both of these uses, your customers become your sales force and it does not cost you a dime for their efforts except for the initial cost of the flash drive. The capacity and cost can vary accordingly from 1 GB to 64 GB.