Nekochan Net

Official Chat Channel: #nekochan // irc.nekochan.net
It is currently Wed Apr 16, 2014 11:19 pm

All times are UTC - 8 hours


Forum rules


Any posts concerning pirated software or offering to buy/sell/trade commercial software are subject to removal.



Post new topic Reply to topic  [ 8 posts ] 
Author Message
Unread postPosted: Fri Aug 26, 2005 1:08 pm 
Offline
User avatar

Joined: Wed Apr 06, 2005 1:29 pm
Posts: 182
Location: M.E
This week I heard something that sounded very strange to me , there was this man who does wiring for studios , and he said that SDI video has the same quality as component analoge and that SDI is being used mainly for ease of use ( less cables going around )

I was like 'huh' ???

does anyone know if this is true ?


Top
 Profile  
 
 Post subject:
Unread postPosted: Sun Aug 28, 2005 11:27 am 
Offline
User avatar

Joined: Sat Mar 20, 2004 5:23 am
Posts: 589
Location: The Netherlands
SDI can be compared to component analoge video as you can compare Hi8 to MiniDV.
They both can carry the same resolution but Hi8 does have all the disadvatages of analoge video.

This is probably not a very good example but it does give you an idea in what direction to think.
( DV is digital video but in order to get the smallest digital stream possible it does compress
color information in a big way. You can see the result of this when trying to use a chroma key
on some DV footage :wink: )

As where the quality is concerned SDI is far better than lets say RGB analoge video.
The SDI signal in a video cable is made up of 1 and 0's, this means that all the video information
is completely digitized before it enters the stream.
This includes the color coding, scaling and levels which are all digital.
It can carry a video signal for more then 200 meters whithout any loss what so ever.
This opposed to analoge component video where the cable lenght of the 3 ( RGB or Y, R-Y, B-Y ) components must be
exactely the same and no longer than 50 meters in order to prevent artyfacts in the resulting signal.

So you can conclude that both systems have the same resolution in video quality but in practice
SDI is the overall winner.
And this is not only the result of carrying the signal from one room to the other over a certain distance
It has also to do with the complete line of recorders and player mixers switchers DVE's and so on.
Because the SDI core of these systems is digital and not analoge.

I hope this will clear up some ...

_________________
I can feel it, my mind is going ....


Top
 Profile  
 
 Post subject:
Unread postPosted: Tue Aug 30, 2005 7:31 pm 
Offline
User avatar

Joined: Wed Apr 06, 2005 1:29 pm
Posts: 182
Location: M.E
This is exactly what I always thought untill this weird discussion

When I met him later I tried to find out what he really meant , and his argument was that digibeta's have D to A converter internally that processes the image in Analogue then a D to A at the output , so the signal is analogue internally anyways

another peice of information I have serious doubt about , but I'm no expert in tape players though , have to double check


Top
 Profile  
 
 Post subject:
Unread postPosted: Tue Aug 30, 2005 9:22 pm 
Offline
User avatar

Joined: Tue Nov 02, 2004 10:44 am
Posts: 411
Location: California
What? I have heard some strange things, but this is not correct - what he MAY mean (and I only somewhat believe this) is that you can, if properly configured, get a cleaner signal through a BetacamSP and it's component signals than on a Digi. Heard that one from Dave Blum, and so it sounds good, but a little weird...
Digi signals are slightly compressed and are, well Digital, I don't think that the signal on the tape is really Analog and there are just D/A on the input and A/Ds on the output.
of course I can also be wrong about this, but I think I'm pretty sure on this one.


Top
 Profile  
 
 Post subject:
Unread postPosted: Sat Mar 04, 2006 11:25 am 
Offline
User avatar

Joined: Sat Feb 07, 2004 5:43 pm
Posts: 453
Location: Lubbock, Texas
BetacamSP is only as good as your technician. It's a lot easier to maintain a digital deck than an analog deck. In general, the digital decks either work or they don't. Analog decks have a wide range of quality depending on how the heads, tension, etc are adjusted.

I would believe that BetaSP can put out a better image than DigiBeta, but only if the BetaSP was a PVW series deck, had new heads, was recently adjusted and tuned, was using a brand new tape, AND was a first generation copy. See where I'm going with this?


Top
 Profile  
 
 Post subject:
Unread postPosted: Sun Mar 05, 2006 6:49 am 
Offline
User avatar

Joined: Sat Mar 20, 2004 5:23 am
Posts: 589
Location: The Netherlands
colin wrote:
I would believe that BetaSP can put out a better image than DigiBeta, but only if the BetaSP
was a PVW series deck, had new heads, was recently adjusted and tuned, was using a brand new tape,
AND was a first generation copy. See where I'm going with this?


We must concider the way this platform of analoge versus digital is stated.

Here's an example, due to the way the analoge signal is recorded onto the tape of an Betacam SP
machine, there's a factory garantee that you will record or playback one dropout every ten minutes.
( this is stated by SONY, you know the guys who invented and build the thing... )
And concidering that SP is analoge we're not even discussing signal to noise ratio's here.
You can compare it with tuning in to a radiostation, you never can tune it 100 %.

You don't have these issues with Digital Betacam since the recording and playback of video is
done completely digital, the recording heads are actually writing ones and zeros onto the tape
with a checksum and a lossless compression.
The word lossless here say's it all the 2:1 compression ratio used in a Digital betacam is nondestructive
the signal that is compressed can be extracted with no loss what so ever.

_________________
I can feel it, my mind is going ....


Top
 Profile  
 
 Post subject:
Unread postPosted: Wed Mar 08, 2006 3:18 pm 
Offline
User avatar

Joined: Fri Dec 12, 2003 12:49 am
Posts: 217
Location: Boston, MA
FYI -

I just read an article by Graeme Nattress last week and was absolutely flabbergasted at finding this out:

Clone Dubbing

Some video recorders, such as Digital Betacam do not give the outside world access to the uncompressed data on the tape, so cannot be edited natively. This also means that you cannot do a perfect clone dub of a Digital Betacam tape.

The compressed output, which we use to edit a video format natively, can also allow a perfect clone of a digital tape to be made. You can easily make a perfect (within the bounds of dropout and data related errors which might, theoretically, over many repeated such dubs reduce the picture quality) dub by connecting a firewire cable from one DV deck to another, pressing play on the first and record on the second. Some DVCAM decks will also copy the timecode from the original over to the new copy too.

When tape-to-tape dubbing via an uncompressed SDI output you cannot make a clone copy. This is because the video must be uncompressed on the play-out machine, and then re-compressed on the recorder, which will theoretically reduce the picture quality (perhaps only slightly in the case of formats like Digital Betacam) and not be a perfect clone. In practice, dubbing from Digital Betacam to Digital Betacam over SDI is visually lossless over hundreds of generations, and indeed, the error correction used in Digital Betacam is so good that tapes with errors on them can often be improved through a Digital Betacam to Digital Betacam over SDI dub.


I was really surprised that you can't make a digital clone of a DigiBeta tape.

Nattress really knows his stuff, so I trust him on this.

The full article is here:

http://www.kenstone.net/fcp_homepage/be ... tress.html

Hmmm - I learn something new every day.


Top
 Profile  
 
 Post subject:
Unread postPosted: Mon Jul 17, 2006 9:07 am 
Offline

Joined: Thu Dec 11, 2003 1:33 pm
Posts: 74
but can the naked eye notice the difference on a lets say 14 inch Sony BVM grade one monitor??


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC - 8 hours


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group