Vegas Pro... 8bit vs. 32bit Samples...

[John Miller]

Originally Posted by Bill Ravens

I think you guys are a little confused. Vegas doesn't convert 8-bit data to 32-bit. Universal law-you can't get something from nothing. What Vegas does do is process(as in calculate) the data with 32 bit floating point math precision , instead of 8bit fixed point math. Yes, you get more accuracy(as in decimal places) and less banding.

Just to make an important distinction: the calculations themselves are not 8-bit. They are almost certainly either 16- or 32-bit integer - the latter being most likely. This is what processor extensions such as SSE/SSE2 etc use. Performing true 8-bit calculations is a very inefficient and slow method (ironically). In essence, the incoming 8-bit frame is converted to 32-bit (integer). Once the calculations are complete for a given effect, the new frame is then converted to 8-bit.

For single effects/transitions etc, the 8-bit mode perfectly adequate. For multiple effects on the same frame, that's where the 32-bit floating point becomes a benefit. All the intermediate frames are kept at 32-bit floating point. The downside to 32-bit floating point is that it is very CPU intensive. Beyond simple add/subtract/multiply, calculations can't be done using SSE/SSE2/SSE3/SSSE3 etc. They have to fall back to the ancient x87 co-processor which is v-e-r-y slow.

[Bill Ravens]

John..Thanx. My understanding is, obviously, incomplete. Thanx for speaking up...at last, someone who knows what they're talking about.

[Alastair Brown]

As one of the ones that "doesn't" know what he is talking about, all I can say is to my humble eyes, the 32bit looks a better image. This then spurred me on to correct my 8bit one to look more like it.

[Bill Ravens]

Alastair...

I'm sorry...didn't mean to be insulting. There's so much misinformation coming from people who think they know, myself included in this category, that it's nice to get an explanation that is technically correct.

In the end, the best judge is one's own eyes. Or the customer's ;o)

[Glenn Chan]

As one of the ones that "doesn't" know what he is talking about, all I can say is to my humble eyes, the 32bit looks a better image. This then spurred me on to correct my 8bit one to look more like it.

The dramatic difference is because some (but not all) codecs change behaviour depending on whether the project is 8-bit or 32-bit. This is not that intuitive in my opinion, but is what Vegas does.

If you apply a "studio RGB to computer RGB" color corrector preset onto a clip, it should give the same effect. This is assuming your clip is a codec whose behaviour changes, e.g. HDV or MPEG-2. Also, be in 2.222 compositing gamma (not the other one).

2- The problem originates because of how Vegas is designed... in many cases, Vegas doesn't show the image as it should look in the preview. The Video Preview window is often wrong. And this problem was there all along, before Vegas 8.

3- Some information on how to get your levels correct:
http://glennchan.info/articles/vegas...or/v8color.htm

[Alastair Brown]

Originally Posted by Bill Ravens

Alistair...

I'm sorry...didn't mean to be insulting.

And now you just compound it further by spelling me name wrong!

None taken. I am most definetly in the "throwing rocks at the moon" camp when it comes to getting a handle on this. Like I said, my mistake just led me somewhere interesting, that may end up helping me get better looking footage. Plus I did ask for the "Big Guns", so I guess I got what I asked for.

So....I'm happy!

[Bill Ravens]

Seems like the gun always goes off just when it's pointed at my foot!
Not so sure how big my gun is...LOL.
Anyway, it's been corrected.

[Adam Letch]

2- The problem originates because of how Vegas is designed... in many cases, Vegas doesn't show the image as it should look in the preview. The Video Preview window is often wrong. And this problem was there all along, before Vegas 8.


How then is it possible then to colour correct in Vegas?? If you can't trust what Vegas spits out?

[Mike Kujbida]

Originally Posted by Adam Letch

How then is it possible then to colour correct in Vegas?? If you can't trust what Vegas spits out?

If it's SD, check it on a properly calibrated monitor.
If it's HDV (different colour space) your guess is as good as mine. Most folks are using their HD TV as a reference.

[Bill Ravens]

I tend to rely, pretty heavily, on the WFM to set black and hi-light levels. This methods works quite well for me. Colors are a little more difficult, but, again, applying the right FX level helps a lot. The only thing the Preview window is really misleading about is the sharpness of the image. I tend to oversharpen footage, because Vegas doesn't show previews at the real resolution.

[Glenn Chan]

How then is it possible then to colour correct in Vegas?? If you can't trust what Vegas spits out?

You need to manually set things up correctly.

For DV footage, preview via firewire out to a broadcast monitor (you have to calibrate the broadcast monitor). Use the default Vegas codec.
You can also use the Windows secondary monitor as a preview... check color management, and check the studio RGB box (in the same preferences page).

For HDV footage, either set the Windows secondary preview up correctly (you have to refer to the table). Or, go HD-SDI out.

2- You could also apply a "studio RGB to computer RGB" preset to the video preview level to get things right in certain situations (e.g. when working with DV footage) and looking at the video preview window... but this is dangerous if you forget to take it out.

The only thing the Preview window is really misleading about is the sharpness of the image. I tend to oversharpen footage, because Vegas doesn't show previews at the real resolution.

?
You can set the video preview window to show full resolution (don't use the draft mode or half-resolution modes), make sure that the video isn't stretched to fill the video preview window, use the (full) preview modes, and turn off simulate device aspect ratio.

Granted, in some cases you can't have it all (fast preview, correct PAR) and get resolution looking as it should be (1:1 pixel mapping).

[Adam Letch]

as usual always prompt and willing and helpful, I know your efforts are greatly appreciated on this forum.

Regards

Adam

[Adam Letch]

you've been great as well, just some of the many people that make this forum so worth while!

Cheers

Adam

[Bill Ravens]

Glenn...

Even with these settings, the images are blurry and out of focus when viewed via a Windows Secondary Display. The same footage is razor sharp when viewed on the same monitor on an application outside of Vegas.

Adam...
Thanx, mate.

[Stuart Campbell]

So, (please excuse the cameraman who's not an engineer)! would V8 let you edit 8 bit footage in 8 bit and any transitions, effects and CC occur in 32bit? Or does it have to be all one and not part of the other? From a discussion currently ongoing in the JVC GYHD forum Paolo Ciccone recommends editing in 8 bit then export to AE for example and carry out any compositing and CC work in 32bit. Reason being any CC work done to 8bit in 8bit tends to impair the original work.

I've been looking at maintaining the image quality right to the end but have been finding any CC work or compositing does slightly impair the result. I'm now considering using something like Adobe AE (if this is compatible with VEgas???) to carry out anything additional to normal cuts. However, having not yet installed the V8 upgrade from 7 can I save myself the cash and use V8 to do all CC work in 32bit?

Stuart