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Q: Compressing avi files ( Answered 5 out of 5 stars,   2 Comments )
Subject: Compressing avi files
Category: Computers > Software
Asked by: nautico-ga
List Price: $5.00
Posted: 02 Nov 2003 07:08 PST
Expires: 02 Dec 2003 07:08 PST
Question ID: 271867
I'm looking for a good user-friendly program for compressing avi video
files for email attachment and transmission. Has anyone had any
personal experience with such a program and, if so, what are the
mechanics of using it for compression?

Clarification of Question by nautico-ga on 02 Nov 2003 11:01 PST
I create the avi's from within Logitech's Image Studio, the software
companion to the Logitech webcam. The program is designed to produce
an avi file, then further compress it before it's attached to an email
msg. My Image Studio, however, is giving me an error msg (invalid
class string) just as it starts the compression, such that a
compressed version of the file doesn't get created. If I want to
attach the uncompressed file. I have to save it to the desktop and
attach it from outside Image Studio (i.e., in Outlook Express).
Nothing in Logitech's web site alludes to this issue, though I have
emailed tech support. If I don't get a satisfactory answer from
Logitech ("within 2 business days"), I'll continue to seek a third
party program that will accomplish the FURTHER compression. Without
that further compression, a 10-sec avi amounts to 800+KB!
Subject: Re: Compressing avi files
Answered By: hibiscus-ga on 02 Nov 2003 13:40 PST
Rated:5 out of 5 stars
Hi Nautico, 

As shiva777 pointed out, it's often not possible to compress an AVI
file.  Somewhat like a Zip file, AVI is usually already compressed. 
But unlike a Zip, AVI files can take all sorts of formats, some
producing small files, some large, and some using no compression at

The compression is controlled by the codec that is used when writing
the file, and on the various settings of the codec.  A codec is an
application that takes the raw video data and performs the compression
that gets written into the AVI file.  It is also used to decode the
compressed file for playback in the video player application, like
Media Player.

Your problem may be that you are just writing a raw AVI file, in which
case you'll end up with a gigantic file for even very small clips. 
You may want to see if you can change the codec when saving your file.
 Unfortunately I don't know the Logitech application so I can't help
you with it.

If that doesn't work out, there are simple programs out there for
recompressing video.  A very simple one is called Advanced AVI
Splitter.  It's available here:

If you want to get more advanced you can try VirtualDub, available
here: but I wouldn't recommend it for
simple tasks.

I'll give you some basic instructions on how to recompress your file
using AVI Splitter.

To recompress an AVI file, open the original AVI file from within AVI
Splitter.  Select the start and the end points of the file that you
want to output (you can, as the name suggests, split the file into a
smaller segment if you wish).  Do this by sliding the location slider
all the way to the left (first frame), then clicking the Start
Selection button (a blue line with a 1 under it).  Slide the location
slider to the end, click the End Selection button (blue line with a 1
and 2 under it).  Now save the file.

In the save dialog box you can click the check box for 'Recompress
video stream' and then click the Choose button to select a codec. 
You'll probably have a few already installed on your system, and you
can use one of those if you like.  Microsoft Video 1 or the Intel
Indeo codecs are likely to be there.  But if you want very small file
sizes you should download and install the DivX codec from which is free.

The settings on the DivX codec can be a bit daunting, but you can
probably just accept the defaults and you'll find the file size is
much smaller than what you're getting now.  If you want to make it
smaller still you can click the Configure button in the codec
selection box and reduce the encoding bitrate.  This just means that
there's more compression on the file, though the tradeoff is a lower
image quality.

You should be aware that in order to view the DivX encoded file your
recipient will also have to install the DivX codec.

I hope this helps you out with your video troubles.


Request for Answer Clarification by nautico-ga on 02 Nov 2003 14:19 PST
I installed Advanced AVI Splitter. Your instructions were followable
until I got to Recompress Video Stream. The single choice for video
codec was Cinepak Codec by Radius. I next clicked Choose, got the
Video Compression window and a drop-down menu of the following
compressor choices:

Cinepac Codec by Radius
Intel 4.2.0 Video V2.50
Intel Indeo(R) Video R3.2
Intel Indeo Video 4.5
Intel IYUV Codec
Microsoft RLE
Microsoft Video 1
Indeo Video 5.10
Microsoft H.263 Video Codec
Microsoft H.261 Video Codec
Intel I.263 Video Driver 2.55.01
DivX Pro 5.0.2 Codec

How does one know which of these to select?!

Request for Answer Clarification by nautico-ga on 02 Nov 2003 14:23 PST
I just tried compression using the Microsoft Video 1 codec and,
ironically, the allegedly compressed file turned out to be larger than
what I started with (2.76MB vs. 2.16MB) for a 10-second file!

Clarification of Answer by hibiscus-ga on 02 Nov 2003 14:56 PST
Hi Nautico, 

It looks like you already have the DivX codec installed which is a
good thing.  Select DivX Pro 5.0.2 Codec and then click configure to
adjust the bitrate.  700 is usually perfectly good for the average
video, but you may be able to make it smaller without too much quality
loss.  You'll have to fiddle with it a bit to see what you get.


Request for Answer Clarification by nautico-ga on 02 Nov 2003 15:20 PST
This gets curiouser and curiouser. I used the DivX codec, or at least
tried to, but got the following error msg: floating point division by
zero. Huh??

Clarification of Answer by hibiscus-ga on 02 Nov 2003 18:40 PST
Hmm.. that's frustrating, and very strange.  

The divide by zero could be caused by a bad AVI source file, or it
could be something funny on your computer.  Probably the first place
to start is to get the latest version of the DivX codec (it's at 5.1
now) and try again.  If that doesn't work either then I suppose it's
possible that it's the AVI Splitter program, in which case we can try
something else.  I can give you instructions on how to do what you
want with VirtualDub, but it's considerably more complicated, so I
think for now you should try upgrading the codec and see how that

Let me know if that still doesn't work for you.


Request for Answer Clarification by nautico-ga on 03 Nov 2003 05:20 PST
I'm already using DivX 5.1. I've emailed DivX tech support about that
error message. Perhaps it's a common issue. Will also call Logitech
today and approach the question from that end as well. In any event,
you have expended more than enough effort here for my meager bid, and
so I am closing this question. Many thanks.

Clarification of Answer by hibiscus-ga on 03 Nov 2003 08:51 PST
I'm sorry it hasn't been as easy as you might have hoped.  With luck
that error can be tracked down.

If you do decide to try another application, some very quick
instructions on using VirtualDub (which can be a terribly overwhelming

Open the file in VirtualDub, then on the menu select Video -> Full
Processing Mode (this means that it will re-analyze the data strem
when saving).  Then click Video -> Compression and select your codec. 
Click OK to get out of that window.  If you want to try to recompress
the audio to a smaller size too click Audio -> Full Processing Mode,
then select Audio -> Compression. MP3 compression is best, and usually
something in the 3 to 4 kb/s range is good enough.

Then just save the file by clicking File -> Save As AVI Format.

Best of luck to you with all of this.  Video files are finicky and
often annoying.

And also, thanks for the tip!

nautico-ga rated this answer:5 out of 5 stars and gave an additional tip of: $5.00
Many thanks!

Subject: Re: Compressing avi files
From: shiva777-ga on 02 Nov 2003 10:51 PST
AVI is video that has already been compressed. Similar to MP3's
running them through Winzip or something similar would probably yield
very little more compression. I've never tried, but I'm pretty sure
thats the case. Maybe some researcher here will prove me wrong.
Subject: Re: Compressing avi files
From: nautico-ga on 03 Nov 2003 08:25 PST
I solved the problem! Called Logitech tech support and learned that I
needed to download and install the latest version of MS's Windows
Media Encoder.

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