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Let’s Make Movies

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PCQ Bureau
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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.

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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

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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.

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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

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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.

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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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