Re: Lossy & Compression

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From: noone (anonymous_at_discussions.microsoft.com)
Date: 03/20/04 

Date: Sat, 20 Mar 2004 12:31:07 -0800

I seem to have missed several messages on this topic. I had not realised that a comparison between what you can get with a bmp against a jpeg still image was in question or that putting the resultant compressed file onto a cd. I just wanted to say that here I can compress a DV-AVI file so that it ends up being 2/3 its original size, I have now tried it with the three files I have the results were 30% for a 114mb file, 34% for a 1.8gb file and 28% for a 1.5gb file. I would say that that result is a long haul from what bob said. maybe i am wrong but lets not labour it any more
     
     ----- PapaJohn (MVP) wrote: -----
     
     When I think about compression, like taking a BMP image and making a zipped
     file from it, I expect about 85% compression.... and I don't expect much
     gain when compressing a JPG....
     
     I think Bob's point is valid in that the gain by a zipping isn't substantial
     because of the already compressed nature of the format... but sometimes a
     30% gain is all you need to make a short DV-AVI clip fit on a CD without
     having to get into multiple discs.
     --
     PapaJohn
     
     Movie Maker 2 - www.papajohn.org
     Photo Story 2 - www.photostory.papajohn.org
     
     ..
     "noone" <anonymous@discussions.microsoft.com> wrote in message
     news:4D2B7A3C-82FB-41DB-9259-F95106AE691F@microsoft.com...
> Hi Bob, yes thats right, you did not say you could not compress it....you
     said You will not be able to compress it much (if any) more by zipping it
     and all I was trying to show was that even with a fairly small DV-AVI you
     can get up to 30% compression. as the size of the file to be compressed
     increases then usually so does the chance of even higher compression.
>> you should try compressing a small file you can sometimes end up with a
     file that is bigger than the original and thats because of the gain
     compressing the small file is less than the overhead in tagging all the
     code.
>> I did not realise that DV-AVI was compressed I always thought it was a
     differential stream of data and sometimes called RAW. I suppose you could
     call that a compression of a kind.
>> you might also be interested to know that the new version of winzip has an
     even higher compression capability. I did not use that higher ability in my
     examples because it is only available to users of version 9.
>> ----- Bob [MVP] wrote: -----
>> I didn't say you could not do it. I just said you wouldn't be able
     to
> compress it much more. And the reason I suggested that you not waste
> your time, is that I assumed you were going to try to compress much
> larger files, like several GB.
>> But the main point I was trying to make was that DV-AVI video _IS_ a
> compressed format. Many people incorrectly believe it is
     uncompressed.
>> -Bob
> ____________________________
> Microsoft MVP
> Windows XP Media Center Edition
> www.microsoft.com/ehome
>>> "noone" <anonymous@discussions.microsoft.com> wrote in message
> news:96F02072-2120-4101-9915-CF8814FCC70A@microsoft.com...
>> My message was to Bob, who said that you cannot zip a DV-AVI file.
     I
> was telling him that you can by up to 30% and still have access to
     the
> uncompressed format of DV-AVI. It was not meant in any way to be a
> comparison over what the uncompressed video quality of a DV-AVI would
     be
> like when compared to the highly compressed and lossy format of WMV
>>

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