Watching movies on the PC using MPEG...
Ken Neo; Neo Mai
03/05/98 The New Straits Times
The New Straits Times Press
Computimes; 2* Page 37
(Copyright 1998)
NOT so long ago, many of us may have said "Boy, wouldn't it be great to watch movies on a personal computer (PC)". Presto, today that wish has come true. It is no longer a secret that you can watch blockbuster movies on your PC. In fact, the movies that you see on the PC are as good as those you see on hi-fi video cassette recorders (VCRs) or laser disk (LD) players.
Thanks to a great technology known as MPEG or motion picture experts group which has enabled us to store digital video nicely onto optical disks.
As you have probably known, digital video requires a huge amount of storage space. It is basically a storage-hungry "monster". However, it too can be tamed by a device known as a video codec . Codec stands for compressor/decompressor and because of it, the PC is able to process digital video.
A video codec allows raw digital video to be compressed as well as decompressed.
Video compression technology is very important as it is the only viable and cost-effective solution to handle the digital video monster on the PC.
MPEG was developed to do just that. Unlike the traditional video codecs like Indeo and Cinepak, MPEG allows digital video to be played at full screen from an optical disk like a CD-ROM as easily as we play a video tape in our VCR. MPEG has become a well-accepted standard for playing movies on our PC. A popular carrier of MPEG movies is the video CD (VCD). You can find many of them today in a wide variety of music retail outlets. VCD can be played on both your PC and TV.
There are three types of MPEG that have been developed so far. The video compression that is used in VCDs is known as MPEG-1 video. Another version of MPEG is MPEG-2 (refer to Figure 1).
Currently, MPEG-2 is being used in many satellite and broadcast stations around the world as well as in the current digital video disk (DVD) movies. The third type of MPEG is MPEG-4.
MPEG-4 is still in its development stage, but it is expected to be released by the end of this year. MPEG-4 is expected not to require such large bandwidth like its predecessors MPEG-1 and MPEG-2, and would be used for streaming video on the Internet and video-conferencing purposes.
There will not be a MPEG-3 compression for video because it was incorporated into MPEG-2 specifications. Since the last year or so, the talk of the town has been on MPEG-2 video.
Through its use in DVD movies, MPEG-2 has brought viewing movies at home to a higher plane. Like all codecs, the digital video has to be encoded with an MPEG-2 encoder during the development stage. Also, in order to playback MPEG-2 video, a MPEG-2 decoder is required.
The development of MPEG-2 started in 1988 and was finally approved in the fall of 1994. There are three standards to MPEG-2. The first was given the International Standard Organisation (ISO) standard 13818-1 which covers the MPEG-2 system stream.
The second was given the ISO standard 13818-2 which covers MPEG-2 video and the third was ISO standard 13818-3 which covers MPEG-2 audio.
All three of these ISO standards were approved in 1994. MPEG-2 has several video resolutions ranging from 352 by 240 to 1,280 by 720.
The most common resolution is 720 by 480 whereas the 1,280 by 720 resolution is designed for high-definition TV (HDTV) applications.
The developers of MPEG-2 have also enhanced the quality of the audio. In MPEG-2 audio, there are five channels and a subwoofer channel of digital sound.
To play your MPEG-1 VCD movies on your PC, you must have either an MPEG- 1 decoder card installed in your PC or a fast PC with MPEG-1 decoder software installed in the system. There are numerous MPEG-1 playback cards and software decoders available to users. An example of MPEG-1 software decoder is XingPlayer from Xing Technologies Inc.
Like the MPEG-1 decoders, MPEG-2 decodes fall into two categories. The first category is a hardware decoder which is a circuit board with MPEG-2 and AC-3 decoder chips installed in the PC.
The second category is a software-based decoder that can be installed into your hard drive but will rely on the power of the central processing unit (CPU) to decode both the video and audio data.
MPEG-2 hardware decoders have existed for several years and are being used mainly in broadcast companies.
However, today, MPEG-2 technology is available for the PC market.
MPEG-2 hardware decoders come bundled with DVD-ROM drives.
DVD-ROMs are similar to CD-ROMs in that they allow users to play CD-ROM as well as DVD-ROM disks. To take advantage of MPEG-2 capabilities, an AC- 3 decoder card is also required.
Most DVD-ROM bundles today are available from companies like Creative Labs and Pioneer.
As for MPEG-2 software decoder programs, it also requires a fast CPU to decompress and play MPEG-2 video and AC-3 audio.
These software decoders have been around since early 1996 and manufactured by companies such as CompCore Multimedia and MediaMatics.
Among these manufacturers which produce such software, they all agree that at minimum, the CPU should be an MMX-based CPU. The MMX-based CPU is already a common feature in most PCs such as the Pentiums and Pentium II machines.
Three different types of MPEG video codec :
* MPEG-1: Used in VCDs
* MPEG-2: Used in DVD, cable TV, satellite broadcast, HDTV
* MPEG-4: Still in development stage. To be used in video-conferencing, streaming video and other Internet applications.
The writers have co-authored the book The Multimedia Mosaic: Multimedia on the PC and can be contacted at Tel. 03-732-5996, Fax: 03-732-5996 or E- mail: kneo @pc.jaring.my.
Caption: Figure 3: A Creative Labs DVD ROM drive. |
