Re: Lossless Compression

["Steve D" <steve@xxxxxxx>]

Sorry, wrote this hours ago, but outlook never sent it till a bit ago
:(
please ignore it, iv'e read the rest of the thread...


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 -----
From: Steve D
To: ukha_d@xxxxxxx
Sent: Tuesday, May 28, 2002 12:35 PM
Subject: Re: [ukha_d] Lossless Compression


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 -----
From: Kenneth Watt
To: ukha_d@xxxxxxx
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@xxxxxxx
Subject: 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.

Jason


----- Original Message -----
From: Kenneth Watt
To: ukha_d@xxxxxxx
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.


For more information: http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx
Subscribe:  ukha_d-subscribe@xxxxxxx
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx
List owner:  ukha_d-owner@xxxxxxx
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

For more information: http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx
Subscribe:  ukha_d-subscribe@xxxxxxx
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx
List owner:  ukha_d-owner@xxxxxxx
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.



For more information: http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx
Subscribe:  ukha_d-subscribe@xxxxxxx
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx
List owner:  ukha_d-owner@xxxxxxx
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.


For more information: http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx
Subscribe:  ukha_d-subscribe@xxxxxxx
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx
List owner:  ukha_d-owner@xxxxxxx
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.



For more information: http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx 
Subscribe:  ukha_d-subscribe@xxxxxxx 
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx 
List owner:  ukha_d-owner@xxxxxxx

Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.