by January 1, 2001 0 comments

The technical concepts of video are similar to audio. Like
samples in audio, video has segments and chunks. Without getting into the
details, we can safely say that the header of the video file includes the number
of frames stored, the time delay between the frames, and the height and width of
the video frame. It also contains other information, like the way the audio data
is stored along with the frames. A common term used in digital video is codec (COmpression/DECompression).
Codecs are specific to video formats and each codec differs in its inherent
coding. So, you need to install the codec of a particular video before you can
work on the video. You must also always work on videos using the fastest machine
you can find because video editing and conversion is an intensive process that
requires a lot of power, RAM, and hard disk space.

AVI

Most digital recordings are first made in Audio Video
Interleave (AVI) because it doesn’t use any compression. This keeps all the
data intact, making it better to work with. AVI is a format originally meant for
Microsoft’s Video for Windows standard. Once you’ve recorded something in
AVI, you can use any of a host of tools available that allow you to convert them
to other formats like MPEG or MOV. AVIs can be edited using tools like Adobe
Premier. Several freeware and shareware tools are also available to cut, paste
or add special effects to them. AVIs can be made using webcams or video capture
cards that can take video cameras, VCRs, etc as the input.

MPEG

The first file format introduced by MPEG (Moving Picture
Experts Group) was the MPEG-1. This is a compressed format that is optimized for
CD-ROM video, i.e., video-CDs. Because it is compressed, it is a ‘lossy’
format (one where you lose some data to achieve compression). It supports data
transfer rates of up to 1.5 Mbps. Just as redundant data in wav files is removed
to create MP3s, MPEG encoding uses the Discrete Cosine Transform (DCT) algorithm
and Huffman encoding to remove redundant data from each video frame. Some data
is also removed from between frames by using motion compensated prediction. The
audio inside videos is also encoded and compressed. MPEG-1 claims to be better
than VHS in quality. However, MPEG-1 encoded video is blocky to look at and
often glary too. The audio, too, is trimmed down.

The version after MPEG-1 is the MPEG-2 standard. This uses a
different and much better variant of MPEG video and a different audio
compression algorithm. MPEG-2 is meant for broadcast quality video and supports
coding at above four Mbps. It is used for digital TV signals and putting video
on DVDs. Software and hardware that works with MPEG-2 is also compatible with
MPEG-1.

You may ask, ‘What about MPEG-4?’ Sure, it is becoming
popular, especially amongst freelance developers. Big companies are jumping on
the bandwagon and trying to be the first ones to hit the market. However, it is
not clear as to what the standard is. Some even confuse it with DivX.

RealVideo

RealNetworks has been one of the forerunners in the field of
providing streaming content over the Internet. Video content is streamed in the
RealVideo format. This content can either be stored on remote servers or could
even be live. RealVideo uses a variety of data compression technologies to suit
the the available bandwidths. Such content can be streamed both over normal IP
connections as well as IP Multicast connections. Because video data needs to be
compressed a lot to be transmitted over the Internet (due to obvious limitations
of bandwidth), the video quality gets compromised. The compression and encoding
algorithms used here take out a lot more data from the actual video as compared
to other encoding methods.

ASF

Microsoft came out with ASF (Advanced Streaming Format) as a
contender against the Real Media format. Again, as in the case of Real Video,
ASF content can be either on remote servers or live. The links to ASF streams
are called ASX, which can be put up on Websites. Not many Website developers use
ASF as a streaming solution because it is difficult to setup. But on corporate
LANs running on Windows 2000 servers, it makes sense to setup such a streaming
server because the content creation software is a component of Windows 2000.

QuickTime

Apple has their own audio and video formats. Like the AIFF
for audio, there is QuickTime (QT). It is interesting to note that QT was
decided upon as the basis for the new MPEG-4 standard by ISO.

Home videos

For home videos, you have the option of video tapes, VCDs,
laser discs (LD) and DVDs. Video tapes have been the storage medium for ages
now. But their limitations are similar to audiotapes’. Also, the amount of ‘work’
you can do with video video tape is limited and cumbersome. VCDs revolutionized
the home entertainment market mainly because of their better video quality and
longer life. In fact, now you can even play a VCD on an ordinary PC. LDs never
really took off in the market because specialized hardware is required to play
them. Then came DVDs that give even better picture quality, but are expensive,
and currently hard to find in the country. Worldwide, DVDs have become very
popular. VCDs store data as DAT files while DVDs as VOB files.

Does all this jargon worry you? Well, once we get down to the
actual job and you see the magic, your worries will disappear.

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