More Cineform questions regarding 8-bit vs 10-bit

[Steven Thomas]

David,

I'm currently using NEO HDV with Sony Vegas and the JVC GY-HD100U.
My current production target is for the very best image possible for DVD and HD-DVD.

Looking at your example 8-bit to CFHD 10-bit export example:
http://www.cineform.com/technology/Demo10bitVS8bit.jpg

It would of been interesting if this example also included three more images:

Image A. = 8-bit original exported to uncompressed (8-bit).
Image B. = Gamma 0.4 applied to image A exported to uncompressed (8-bit).
Image C. = Gamma 2.5 applied to Image B exported to uncompressed (8-bit).

I'm wondering what the color gradient banding looks like if all changes remain in an 8-bit format. From your example, it's obvious that converting the 8-bit original to 10-bit then applying multiple color corrections, color banding was apparent when converted back to 8-bit. The color changes to 10-bit look great.

I guess I'm wondering if this gradient banding issue is due to the image once having 10-bit information which is lost now from the 8-bit conversion. If the same color corrections were done and stayed in its native 8-bit format, would we still have a banding issue? I guess the exact same color conversions can not be done due to the limitations of the 8-bit color palette. But I'm interested in if the exact gamma changes made in 8-bit opposed to your 10-bit samples.

I'm guessing the banding in my additional tests would not be as much as the example 8-bit (D) conversion?
Similar in a manner of taking a 256 (8-bit) color jpeg image and changing it to 24bit and making color changes, overlay, etc.. and then saving it back to 8-bit. There would be a lot of banding. If I stayed with the 8-bit and made all the edits in this 256 color library, the export would have the same gradient 8-bit changes with no additional banding short of to what 256 colors offers in the first place. This may be a bad example, but am I thinking correctly here?

I'm just trying to understand the VERY best image path in taking HDV 4:2:0 to DVD and HD-DVD. NEO HDV has proved to be an excellent intermediate (4:2:2). I'm wondering if I should go to NEO HD?

I just bought NEO HDV maybe two weeks ago.

[Rob Johnson]

Originally Posted by Steven Thomas

David,

I guess I'm wondering if this gradient banding issue is due to the image once having 10-bit information which is lost now from the 8-bit conversion. If the same color corrections were done and stayed in its native 8-bit format, would we still have a banding issue?

The answer is yes. The idea is to perform color corrections/effects/compositing in a 10-bit environment through the processing stage of the data, thereby retaining 1024 levels to work with. I have experimented with what you're talking about and there is an appreciable difference, enough to make or break a film. If you work with 10-bit all throughout the processing stage where all of the heavy arithmetic operations are taking place, the final product will be far cleaner with much less banding when ultimately exporting to your 8-bit delivery format.

This was the first concept cut of a project I worked on using only Aspect HD in 8-bit. There were a lot of effects and multipass renderings being done to most of the footage, I believe 6 iterations (CF exports) in all before exporting to H.264 for web delivery. The banding is readily apparent. So much so that, if I ever wanted to transfer this to film, or even DVD, it would be out of the question.

Fallen Rider

I am currently reworking the project in Prospect HD and no such banding is present.

[Steven Thomas]

Thanks Rob,

Since I mainly use Vegas as my editor, I will probably wait until Vegas supports 10 bit. It seems odd there's no support for this. Also, since Sony now owns Vegas, it just may never happen.

[Rob Johnson]

Originally Posted by Steven Thomas

Thanks Rob,

Since I mainly use Vegas as my editor, I will probably wait until Vegas supports 10 bit. It seems odd there's no support for this. Also, since Sony now owns Vegas, it just may never happen.

Wouldn't know about Sony Vegas since I've never used it. Hopefully they will support 10-bit soon. I should have mentioned in my earler reply that the H.264 compression of course does accentuate the banding to some degree. But this is probably assumed.

The source file does look better in the NLE, but the H.264 is only accentuating what's already there. So I suspect the results when exporting to any delivery format (i.e. MPEG2 DVD) would be similar even at a higher bitrate. It's something of a subjective matter and up to the producer to decide whether it's acceptable or not for the target audience. I'd send you the CF source file if it wasn't 420MB. However, if you'd like to see it, I'll cut out a small 20MB or so chunk, where I think the banding is most pronounced, and upload it to MegaUpload where you can retrieve it.

Rob

[Paul Kepen]

So with Vegas being 8 bit, there would be NO advantage to using 10bit Prospect vesus 8bit Aspect ?

Or would the 10bit Prospect still be able to smooth the banding effects in the final output?

Finally, is the entire Adobe CS3 suite 10 bit, or just After Effects?

Thanks - PK

[David Newman]

Originally Posted by Paul Kepen

Finally, is the entire Adobe CS3 suite 10 bit, or just After Effects?

CS3 is upto 32-bit float in Premiere Pro and AE.

[Serge Victorovich]

David, how to choose 8 bit instead of 10 bit in settings of NeoHD? For editing in Vegas no need 10 bit, but full resolution 1920x1080 is better than 1440x1080 8 bit from NeoHDV.

[David Newman]

We disabled the 8-bit encoding option some time ago for good reasons. Even though Vegas is an 8-bit application, its use of video systems RGB benefits for increases encoding precision. 8-bit RGB is approximately equivalent to 9-bit YUV, and most compressors like CineForm use YUV for internal data storage (it is more effecient.) So converting 8-bit RGB to 10-bit YUV and compressing that guarantees a very accurate construction back to RGB when needed.

[Serge Victorovich]

Thank you, David, for clarification.
Next question:) It is possible when capture via HDMI 1440(1920)x1080i50(60) in real time do conversion to 1280x720p50(60) ?

[David Newman]

Originally Posted by Serge Victorovich

It is possible when capture via HDMI 1440(1920)x1080i50(60) in real time do conversion to 1280x720p50(60) ?

Not yet. We don't have 1080i60 to 60p yet, our deinterlacer only goes to 30p/25p/24p. We do have the downscale, so you can take 1080i50/60 and record 720p24/25/30, however the scaler is CPU intensive, so you would likely need a quad core.

David

[Serge Victorovich]

I dont want (now) 1080p60 :) only 720p50/60.
Just capture every field 1440x540 as frame 1280x720.
This task (upscale 540 to 720) is more cpu intensive and require a quad core cpu...Thanks!

[David Newman]

The correct process is to convert 1080i to 1080p then scale. Scale the fields only can introduce vertical jitter. Anyway we have it on the list of features.

[Rob Johnson]

Originally Posted by Paul Kepen

So with Vegas being 8 bit, there would be NO advantage to using 10bit Prospect vesus 8bit Aspect ?

Or would the 10bit Prospect still be able to smooth the banding effects in the final output?

Finally, is the entire Adobe CS3 suite 10 bit, or just After Effects?

Thanks - PK

I'm really not certain about this, Paul, and wish I could give you a better answer. I do not know how Vegas works for the fact I have never used it or read up on it.

What this all comes down to is you want to avoid primarily 2 things: working in 8 bit when heavily processing video and having any NLE truncating the exported video data back to 8 bit when exporting (unless it is your final delivery export i.e. MPEG2 for DVD or 4 for web). When exporting from PP using the CF format (Prospect), you retain 10 bit. Since I shoot in HD and do a lot of effects which require multipass renderings, this is important to me.

Something tells me there would probably be an advantage to using Prospect over Aspect even in Vegas, but I can't claim that to be technically accurate as much as just a gut feeling. CS3 is 10 bit.

[Paul Kepen]

Thanks Rob for the reply. I did find an answer, and it appears that even with Vegas you are better off with 10 bit Prospect for the reasons you specify and because Vegas is an RGB application. (I forget the details of why this matters). Don't quote me exactly on that, but I believe I read it on the Cineform web site.