Sunday, January 26, 2003

A bad case of geek envy

A DVD player that can also play Divx. Oh boy, do I want one of these.

What does this mean?

Well, in the late 1970s Philips and Sony, but mostly Philips (despite what Sony sometimes tries to imply) invented the compact disc. As most people are aware, this is cabable of storing a total of 74 minutes of music, which takes up a total of 680 Mbytes of data.

If you want to store more than 74 minutes of music, or to store on a disc that requires more bandwidth than does music (for instance video), there are two ways of doing this. One way is to develop a new kind of disc that can store a larger amount of data than can a common CD. The other way of doing this is to compress data containing the music in some way so that 74 minutes takes up less than 680 Mbytes.

In order to fit more data on a disc, the limiting factor is the laser that reads the information off the disc. The smaller the wavelength of the laser, the more data that can fit on a disc. (The CD uses an infrared laser).

The more computing power in the player that will play the disc, the more it is possible to compress the data so that the music (or video) takes up less space without loss of quality.

Initially, the MPEG invented a compression scheme called MPEG-1. MPEG-1 can compress both video and audio. (MPEG-1 compressed audio is often called MP3). With MPEG-1, it is possible to store a lot more than 74 minutes of music on a CD, and it is also possible to store 74 minutes of low quality video. This is known as a Video CD or VCD, and they are incredibly common in Asia.

After this, the MPEG invented a compression scheme called MPEG-2, which allows higher quality video than MPEG-1. On top of this, a new type of disc was invented using a red laser that could hold a total of 4.7 Gbytes. With a combination of the new Disc and the MPEG-2 codec, it is possible to store three or four hours of video. This is the DVD. It is also possible to use new compression schemes to store more and higher quality audio on this new disc. Both the DVD-A and SACD formats do this.

A modern DVD player is capable of playing every format mentioned so far. It can play DVD movies, Video CDs, standard CD audio, and MP3 audio stored on either a CD or a DVD. It would also be able to play DVD-A and SACD audio, except for the fact that the record companies will not allow this because they are frightened of piracy (or something).

The MPEG has invented another compression scheme requiring even more computer power but achieving higher rates of compression: MPEG-4. This allows two or three hours of high quality video to be stored on a CD, and around 20 to 30 hours of high quality video, or two or three hours of high definition video, to be stored on a DVD. There are now official disc formats that use MPEG-4 yet, but the codec is very commonly used on PCs. People frequently use MPEG-4 video to store video that has been transmitted over the internet or generated using a digital camcorder. Having done this, people often use CD and DVD burners to store these MPEG-4 encoded movies on CDs or DVDs. The format that uses MPEG-4 to encode movies on a computer and then store them in this was is called Divx, and this was invented by a PC software company.

However, until now, people have only been able to play these Divx movies back on a PC. This new player is the equivalent of a stand alone DVD player for Divx. This can play back (Divx) MPEG-4 movies that have been recorded using both CD-burners and DVD-burners, as well as standard DVDs, Video CDs, and audio (stored on both CDs and DVDs) in both MP3 and standard DVD format. This is really cool.

Consumer electronics companies such as Sony and Matsushita should be scared sh*tless. They haven't come up with an MPEG-4 based video disc format, but the PC industry has done it for them, and has completely bypassed them . (This happened with MP3 players, too). The consumer electronics companies are, however, working on something called a Blu-Ray disc, which will use a blue laser and will be able to store 27 Gbytes of data. With MPEG-2, this should be able to store three or four hours of high definition television, or 20 hours of so of high quality ordinary television. With MPEG-4, it should be able to store 20 or so hours of High definition television or hundreds of hours of ordinary television. This will be pretty awe inspiring.

Update And here (via slashdot ) we have a hard disc based MPEG-4 camcorder, which eliminates the need for tapes or DVD type discs in the camcorder. It is able to do this, because it uses MPEG-4, which stores the movies in a much smaller space than can the MPEG-2 or DV formats of previous digital camcorders.

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