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There is lossless compresion, though when
deailing
with images lossless is usually the way to go since you can compress it
alot
more.
When you compress a file with winzip do you
lose
words etc? No.
If you cpmpressed a saved raw digital stream
using
something like winzip, it would be lossless. It may not compress as much,
but it
would be lossless non the less.
Steve D
"Regular people say 'if it ain't broke, don't fix it'. Engineers say:
'If
it ain't broke, it doesn't have enough features yet.'"
----- Original Message -----
Sent: Tuesday, May 28, 2002 11:37
AM
Subject: RE: [ukha_d] Lossless
Compression
The point being
Jason
that any form of compression and manipulation of the file *will* introduce loss and affect the
quality of the image. If your digibox
un-compresses
the stream then there is a loss in that, then you are re-compressing it for
storage (loss again), then decompressing it to view (still more loss)…NOT
lossless!
Any form of
capture,
compression or manipulation will introduce certain artefacts into the
picture
whether you notice them or not, although there is many a software “trick”
to
minimise the impact of such manipulation. If you like I can loan you a
couple
of good books that explain this but it isn’t exactly light reading
material.
K.
-----Original
Message-----
From: Jason
Lee
[mailto:jasonjlee@xxxxxxx]
Sent: 28 May 2002 11:27
To: ukha_d@xxxxxxxSubject: Re: [ukha_d] Lossless
Compression
OK, the PC capture of whatever
feed is lossless...
Like taking a file and using
zip
to compress it. The file when uncompressed is exactly the same as the
source.
Lossless
As opposed to using
jpeg/mpeg/mjpeg which uses tricks to compress images down. When the image
is
uncompressed it is not identical to the source. Not
lossless.
Look at matroxusers web site
vcdhelper, any big video editors website for details as to why this is a
good
idea...
I don't only capture from tv, I
capture from dv and my s-vhs deck.
----- Original Message -----
Sent:
Tuesday, May 28, 2002 11:19 AM
Subject:
[ukha_d] Lossless Compression
Jason,
This is really a question for
you...
How are you
achieving
lossless compression with SS?
I was thinking about this last night and the only way I
can see of doing
this is to
take
a feed into a SAT card in the PC direct from the LNB
to
catch the digital stream
before it is decoded thus achieving a lossless
compressed file. The problem with that is that there is
no CAM available
for Sky
Digital
to enable this to be done with a SAT card or
TV.
AFAIK the only way to
do
this, or more accurately, the only system that
can do this, is Sky+ as it actually records the stream
directly and
plays back as it
would be presented straight off the air.
If you are running it through the STB and then
transferring that signal
to
your
SS machine then that is not lossless, you are in fact,
doing
what any PVR or VHS
machine would do.
K.
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