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is SDI no loss medium?

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sushil sharma
is SDI no loss medium?
on May 14, 2011 at 11:38:41 am

well i had no luck in decklink forum so posting it here

will someone help me to do this test and prove that SDI is 10 bit yuv transfer with no loss.

make some material in quicktime 10bit yuv unc codec (anything from your footge, color bars or even some random noise pattern). take the exported clip and playback on one fcp system equipped with decklink card (clip1 ) and capture on another fcp with decklink card(clip2). take both files and apply difference key to them on same exact frames (somekind of timecode in source material will help) to see what has changed in it. if it is same then it will prove the quality of SDI as the ultimate mode in digital production.
plz some one do it because i have searched all the net, found nothing and currently don't have multiple systems to do it myself.


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Bouke Vahl
Re: is SDI no loss medium?
on May 14, 2011 at 1:54:40 pm

No need to test.
SDI is lossless digital, your codec may not be.
And SDI is the industry standard.
But analogue component is lossless as well, but analogue.

Bouke

http://www.videotoolshed.com/
smart tools for video pros


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Andrew Rendell
Re: is SDI no loss medium?
on May 14, 2011 at 5:11:56 pm

SDI is a digital feed of 4:2:2 sampled YUV, with no data compression. I once did a test where I took a picture out of a digibeta deck, into a vision mixer and back onto digibeta, then repeating that. At 40 passes you could see some changes, but that was due to the vision mixer (an Abekas A84) interpolating the bit depth internally, not the SDI links.

Really your test is one that would show whether your system is working properly, rather than to discover anything meaningful about SDI.


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Alan Lacey
Re: is SDI no loss medium?
on May 15, 2011 at 6:22:26 am

SDI spec is here:

http://en.wikipedia.org/wiki/Serial_digital_interface#Standards

Alan

FlashXDR,XDcamHD,XDcamEX,D9 etc
FCS,AE,Combustion,LiquidSilver,Vegas,Edius,
G5,MBP,Vista64,XP


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sushil sharma
Re: is SDI no loss medium?
on May 16, 2011 at 4:04:48 am

thanx a lot guys. so that does mean that if i capture from SDI source into my decklink that video is always of highest quality and can't be challenged for quality issues.
highly appreciated.


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sushil sharma
Re: is SDI no loss medium?
on May 16, 2011 at 4:59:35 am

so does it mean that if video is captured through sdi into uncompressed codec, whichever is the capture card aja decklink bluefish matrox or any other, it will be same.
thanx in advance


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Andy Mees
Re: is SDI no loss medium?
on May 16, 2011 at 6:04:17 am

The quality and length of the cable could potentially cause signal degradation issues (and the "Uncompressed" codec is still, strictly speaking, applying compression as it's recording 422 not 444 ) but basically yes, the quality of the captured footage should be enough to satisfy even your most demanding clients. What you do with it afterwards tho ... ;-)


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sushil sharma
Re: is SDI no loss medium?
on May 16, 2011 at 6:35:50 am

but codec, 4:2:2 and cable length are issues which hold for all capture cards
so if everything is identical except capture card should i make me free of worry that "capture card is degrading footage."
and not think about going for so advertised high quality capture cards.


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Richard Cooper
Re: is SDI no loss medium?
on May 16, 2011 at 5:21:49 pm

"...so if everything is identical except capture card should i make me free of worry that "capture card is degrading footage."
and not think about going for so advertised high quality capture cards."


Well, There are many things to consider here.... and the cheapest route is not necessarily the best way to go. We use AJA cards here, the best customer service in the biz and worth every penny..... Black Magic is another good option as well as Matrox..... They all do the same things AND different things for different needs... look at your needs vs budget and go with what fits your needs the best. None of them will "degrade" the video quality so that does not even need to be part of the equation.

Good Luck!

Richard Cooper
FrostLine Productions, LLC
Anchorage, Alaska
http://www.frostlineproductions.com


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