Tech Tip: Compression for CDs and DVDs Part 3: Video

Written by Donald R.J. White

As mentioned twice above, the real CD and DVD compression advantages are nearly all reserved for images. This is readily understood when looking at a typical photograph. If an outdoor landscape, note the blue sky may take up 20% of the photo. Why waste all the hundreds of thousands of pixels when a few bytes will describe the sky color and then its location, height and width take up a small amount more. Only when the neighboring pixels are exhibiting a change does that information need to be preserved. Thus depending upon the simplicity or complexity, video compression techniques may provide for lossy compressions from 5:1 to 200:1 with 50 being a typical order of magnitude.

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Tech Tip: Compression for CDs and DVDs Part 2: Data

Written by Donald R.J. White

There are different compression techniques that can be used for compressing plain text languages such as English, latin-based, Slovak and the like. Two examples are (1) RLE for Run length encoding and (2) LZ encoding to cover entropy encoding and Lamped-Ziv compression. While impressive compressions are available for video, as described in the next section, the best that can be expected for plain text is about 3:1.

Thus, a strong argument can be used for not bothering to compress alphanumerics at all, especially if there is embedded video such as graphics, sketches, drawings, and photos. For example, assume a report has 80 % plain text and 20% graphics.

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Tech Tip: Compression for CDs and DVDs Part 1: Music

Written by Donald R.J. White

One Byte = 8 bits = 28, or 256 options or quanta levels. CDs can store 670 MB of information and DVDs (single sided) store 4.7GB. DVDs store 4700MB/670MB = seven times more capacity. For example, 50 CDs of music can be stored on seven DVDs. Compression tools can compress disk space from about three to 200 times, depending on the stored information (i.e. text, music, video, etc). Music compresses from 1.2x to 3:1 times (MP3 format for 10:1 times), and text compresses only about three times. But, video can compress enormously, depending upon if is (1) stills, like a picture gallery or a power point presentation, or (2) movies which compress the best (roughly 100 times). The amount of compression of video depends upon the acceptability level (quality control) of lossy compression techniques.

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Tech Tip: Blu-Ray: The Successor

Written by Donald R.J. White

In the mid 1990s, commercial high definition TV (HDTV) sets began entering a larger market. Since there was no cheap way to record or play back more demanding HD content (4x+), and a non-HD movie already takes up the storage of a single DVD, a new media format was needed. Blue lasers with shorter wavelengths for HD DVDs yield optical storage with higher density than red lasers for DVDs (0.62x for wavelength ratio). As a result, two new competing media were created: HD-DVDs (spearheaded by Toshiba) and Blu-Ray DVDs (led by Sony). However, within the past two years, Warner Bros, Best Buy, Wal-Mart and others stalwarts announced they would no longer support HD-DVD format, but join the Blu-Ray camp. In February of 2008, after losing US$ 1 billion, Toshiba announced its decision to discontinue development and marketing of the HD DVDs. Thus, the backers and followers of Blu-Ray technology won the HD "format war".

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Warner Brother's embrace Blu-ray

With all these big studios embracing the Blu-ray format, Microsoft is finding themselves alone in the HD corner... again...

marantz' new Blu-ray player at CEDIA

the good folks at engadget are reporting news on the new Blu-ray player being displayed at this year's CEDIA conference. pictures *YES* and details about audio codecs are included.

smaller size CDs and DVDs...

according to appleinsider.com, apple has issued a patent for "a collapsable hardware solution that would allow [their] company to reduce shipping and packaging costs by selling software on smaller discs which could then be used in slot-loading optical drives built for standard 12 cm CDs and DVDs, a new filing has revealed."

An additional quote states, "Software is traditionally shipped on the 12 cm discs, but many applications exist today that require less storage capacity than what is available on the those discs, the filing adds. However, slot-loading drives found in notebooks and car audio systems are only designed only to accept 12 cm discs."