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Is Betacam sp 3:1:1 or 4:2:2?

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brianluce
Is Betacam sp 3:1:1 or 4:2:2?
on Aug 12, 2005 at 2:14:17 am

I'd always assumed betacam sp was always in the 311 color space. (we use a sony d50) yet our DP said in theory it's 311 but through some kind of hocus pocus technical stuff i didn't understand the sampling is actually 422. clarification?


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R. Hewitt
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 12, 2005 at 2:02:15 pm

If memory serves me correctly, and as it's an analogue format, it can't really be described as either. However the luminance is layed in one stripe whereas the colour components are time compressed into a single stripe giving the effect of compression but it is only in the time domain and is stretched back on playback.

But as in almost all tape formats the colour information is sampled (analogue) at half the rate of the luminance ie, 13.5MHz for the luminance and ~6MHz for each of the colour components.


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Charlie King
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 12, 2005 at 4:41:21 pm

[R. Hewitt] "If memory serves me correctly, and as it's an analogue format, it can't really be described as either."

Exactly!

Charlie



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brianluce
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 13, 2005 at 4:56:32 am

If I'm not mistaken though, people like adam wilt refer to betacam sp as the "equivalent" of 3:1:1.


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Charlie King
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 15, 2005 at 4:29:06 pm

Guess I don't know any people like Adam.

Charlie


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brianluce
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 16, 2005 at 2:45:09 am

here's adam wilt's take:

Chroma resolution on BetaSP is essentially the same as on 4:1:1 DV, so were BetaSP a digital format, its sampling might be characterized as 3:1:1 for comparison purposes. Of course, BetaSP is not sampled on a fixed spatial grid, so such numerical comparisions should always be taken with a grain of salt.



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Charlie King
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 16, 2005 at 5:31:54 pm

I had a long answer typed out and decided this statement doesn't even warrant a reply.

Charlie



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brianluce
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 17, 2005 at 2:22:32 am

no time for providing info to others but plenty of time for nasty sarcasm. I like your priorities.


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Charlie King
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 17, 2005 at 3:16:12 pm

I had already given the information, I'm sorry if you miunderstood my remark. In 44 years in the business I have never heard of 3:1:1. I have never heard of analog being discussed in digital sampling terms. So, my comment was concerning the fact that I have no idea where he gets his philosophies, because I have never met anyone who discusses any of these matters in those terms.

Sorry that you took my comment as nasty sarcasm.

Charlie


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brianluce
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 18, 2005 at 2:33:34 am

I don't know where adam wilt gets his "philosophies" either but they don't hand out degrees from Princeton to every Tom Dick and Harry. So I'm much less inclined to dismiss his ideas.


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Charlie King
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 18, 2005 at 3:09:22 pm

I feel it is best that I not give my "philosophies" of many who have degrees, without experience in the real world.
So I feel it best to drop this discussion with the information I have already given.

Charlie


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R. Hewitt
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 19, 2005 at 10:07:53 am

Nicely put Charlie. I share your sentiments.


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Jonathan Miller
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 19, 2005 at 9:50:36 pm

Is BetaSP so far gone that people don't even understand the not-so-distant analog world?

I don't have my PVW series decks anymore, but it's always pleasant to turn on my UVW-1800 and it says, "Welcome to: Betacam SP" Makes me smile.

As for the postings here I, too have never heard of 3:1:1 and I'm very confused as to why Beta SP would be described in digital sampling terms. That's like making apple juice with oranges.

The correct way to put things would be to say that 4:2:2 is more like BetaSP's analog color bandwidth than DV's 4:1:1 or 4:2:0.

Jon



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Charlie King
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 19, 2005 at 9:54:16 pm

Amen brother Jonathan

Charlie


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brianluce
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 22, 2005 at 8:51:49 am

i think adam wilt was saying that beta cam sp produces an image that for the sake of comparison only, that though it's analog, were it digital, it would be roughly equivalent (note the qualifier "would be") to a digital image sampled at 3:1:1.

I got confused when one of our camera operators began insisting that betacam was 4:2:2. he backed his argument up with some highly technical gobbledigook. i think i should fire the camera operator. i came here for clarification.



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Charlie King
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 22, 2005 at 4:37:52 pm

OK, Digi-beta is 4:2:2 at a 3:1 or sometimes referred to as 2.5:1 compression ratio.
Betacam SP is analog, the color you see is the color you get. One difference you may notice in betacam is it will have some noise in the picture. When that picture is transferred to Digital, it is actually compressed and in the compression scheme the first thing to go is the noise which will give the impression of being cleaner than the analog Betacam.
I believe it is this perception that they may be talking about instead of the actual video quality, or colorimitry.

I hope this helps in your understanding. I apologize if I seemed coy or unhelpful. I just find it difficult at times to understand how a degree seems to make people more knowledgeable when my experience has seen many degrees that couldn't make it in the real world so they returned to a major university to teach. I don't mean any disrespect for anyone, cause I have also seen many degrees that hit the real world with a quest for learning more and those people have gone far, unlike the ones that taunt the degree as symbol that they know everything and are ready to conquer the world of TV, or movies.

Charlie


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glenn chan
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 26, 2005 at 5:49:19 pm

maybe the following article is helpful:

http://www.nattress.com/Chroma_Investigation/chromasampling.htm

Graeme Nattress compares DV and betaSP and digibeta in terms of color and luma resolution.
DV has slightly better luma resolution than betaSP, and slightly worse color resolution.


As others pointed out, betaSP is not a digital format so it's not really 3:1:1 or 4:2:2.
Typically you want to capture betaSP digitally with 4:2:2 color sampling to get the most out of it.


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Charlie King
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 26, 2005 at 6:35:45 pm

After reading the article, I see where it is ery difficult to get really fair comparisons in some areas. For example, starting with Digital Betaca footage, the dubs were made by SDI to the digital formats.
The dub to and from the Betaca SP would have had to be made through the analog output of the Digital Beta, then an analog output from the Beta SP. This in essence has give the eta SP a disadantage from the onset of making the video 2 generations of analog to the final destination. Since analog has losses in generational output. You are not starting with a first generation as you in essence have from the digital sources.

Just a simple observation that makes these types of comparisons a little less than perfect.

Charlie


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ScottGfx
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Aug 27, 2005 at 9:48:15 am

One more thing to consider...

4:2:2, 4:1:1 and 3:1:1 are all ratios. We know that SMPTE 259M (ITU-R 601) and DigiBeta are 4:2:2.

DVCPRO is 4:1:1

Would not 3:1:1 be some sort of guessed-upon tip-of-the-hat to BetacamSP? The ratio actually would seem to indicate a greater amount of chroma sampling to luminance than your run-of-the-mill DVCPRO 4:1:1.

Where I work, we are still in a hybrid Digital-Analog world with BetaSP and DVCPRO. It's a real toss-up. We like the resilience of DVC to tape dropouts, but we like the resulting picture of a BetaSP better. It's also much easier to pull a greenscreen matte from a BetaSP master than a DVCPRO. (Thus would indicate a smaller ratio of Chroma to Luminance sampling)



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glenn chan
Re: Is Betacam sp 3:1:1 or 4:2:2?
on Sep 4, 2005 at 7:35:49 pm

3:1:1 is something adam wilt made up to approximate betaSP sampling to the color sampling digital formats. Graeme's article indicates that betaSP is probably something more like 3.something:1.something:1.something.

Anyways, it may not be too useful to characterize betaSP as 3.something:1.something:1.something.

2- Scott, have you tried applying chroma interpolation or chroma smoothing to the signal from DVCPRO? I believe DVCPRO decks with SDI out do this.


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