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Video Formats and CODECS
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 Avi
or MPEG ?
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The
AVI format is supported in all versions of Windows. The MPEG format
is not supported directly by OS and it require a MPEG software player
installed which supports MCI.
New Windows Media Player can play many formats and MPEG as well.
All new Windows 98 installation should have MPEG support already
installed (or not...). For older versions of Windows you have to
carry the Windows Media Player installation or DirectShow 6 and
newer with you.
MPEG format has better compression and quality than standard AVI,
however it needs more CPU to play the video.
To make it more difficult not all AVI's are the same. AVI uses Codec's
to compress its data. (And in fact it can also use MPEG codec)
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| What
is CODEC ? |
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You can use uncompressed AVI, but you will end up with hundreds of
MB of data just for few minutes. Instead you should use a compression/decompression
software. CODEC is such software component. In order to be able to
play the video encoded with any CODEC the component must be installed
on the computer.
As always there are many Codecs, producing better or worse video quality.
You can choose any one, but remember if you go wild you will have
to also install the CODEC on the user computer before he will be able
to play your video.
There are already few Codecs installed on every Windows95, 98, 2000
by default:
Cinepak, Indeo 3.2, Indeo 4, Indeo 5, Microsoft Video 1.
Each codec is identified by 4 letters code in AVI file (for example
Cinepak is CVID) |
| Microsoft
Video 1 |
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The
original CODEC shipped with ancient Video for windows.
Quality: Bad, it is CODEC from times when 256 colors was a
luxury.
Tip: The best is to avoid this CODEC. |
| Cinepak
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Cinepak
was originally developed by Radius to play small movies on 386 from
CD ROM.
Quality: Many years ago this was amazing, however today it
doesn't compare well with newer CODECs
Tip: All Windows Versions will be able to play AVI encoded
with Cinepak. To play the video, the CODEC need just very little CPU.
If you want to have video play back on any Windows machine Cinepak
would be your choice. |
| Indeo
3.2 |
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Developed
by Intel in 80's
Quality: Not much to say, the quality is in the range of Cinpak
- which means 'medium' quality. It doesn't like fast movement.
Tip: All Windows versions should be able to play AVI encoded
with Indeo 3.2. The time needed for compressing is less than Cinepak,
however it needs faster computer to play back than Cinepak. (Today's
Pentiums are far fast enough anyway) |
| Indeo
4 and 5 |
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Some
name but different technology than Indeo 3.2.
Quality: Produces better results than Cinepak or Indeo 3.2,
but needs fast Pentium
Tip: Most of the Windows 95 and 98 will have this CODEC already
installed. However it requires a fast Pentium to play it back. |
| MPEG-1 |
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MPEG-1
provides excellent quality (audio and video)
This format is very popular and most of the MPEG files you download
from Internet are encoded in MPEG-1.
Also it is the format for VideoCD (VCD). |
| MPEG-2 |
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MPEG-2
is designed for broadcast quality digital audio and video. The image
quality is outstanding. This is the format DVD uses. To play MPEG-2
videos you need fast Pentium or special hardware. |
| MPEG-4
(ASF) |
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MPEG-4
is designed for high quality web streaming video. It is similar
to H.263 (video conferencing CODEC)
The quality is excellent even at low datarates. Microsoft has its
own implementation in the new ASF format.
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DivX:) old hacks
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The old DivX was a simply Microsoft source code for the MPEG-4 from their SDK and hacked very slightly so it could be used in AVI format. DiviX as a codec is the same as used in ASF, however ASF is build as streaming format (you don't have to download the whole thing to play it - unlike AVI) so it has different structure.
Because inside the original DiviX was a Microsoft code it may hapened that they will legaly go against DiviX and other copycats. The other codecs went with various names such as AngelPotion etc.. but they all used the same code.
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| DivX, XVid... |
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The new generation of MPEG 4 codec is a new implementation (non-MS code) of the original idea for a widespread MPEG 4 inside AVI. DivX is now a house-brand, legal commercial company, that just use the old name, but inside is their own code.
There are more and more devices that support DivX and are DivX certified (that means they will play DivX encoded files)
XVid is an open source MPEG 4 codec that decodes DivX and other MPEG 4 variations. XVid files should be playable by DivX players.
The audio in DivX files is usualy mp3, but also ac3 is sometimes used (that creates problem with older DivX players)
A MPEG 4 has a bright future because of its appealibg compress ratio, that is 3-4 times higher than of MPEG 2 for similar quality and much higher for just a slight quality loss. This makes DivX a prime candidate for on-demand internet movie services.
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| So
which CODEC? |
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Well
that's again your choice. There is no one for all. If you look at
the previous paragraphs it looks that if you want to play video on
any windows computer you use AVI format encoded with Cinepak. The
quality is nothing to write home about, but it will play on all computers
for sure. If your video has low motion (boring talking head) you can
also try Indeo 3.2
CODEC. Then if the quality is important use MPEG, but you have to
let user install Microsoft Windows Media Player first (it is free) |
