32 bit for intermediaries?

jrazz wrote on 10/2/2007, 7:25 AM
I am working on some footage that I want to utilize 32 bit video for as it will be output back out to 8 bit but I want to saturate where possible and do some CC. I have a piece of footage that I will be encoding several times to speed it up to the desired speed (Cineform 60i). This will initially not have any CC or saturation done to it until I add the event to the timeline at the speed I want it. It does contain a lot of changing shades of colors (sunrise). Do I need to apply 32 bit video to the intermediaries or just the final encode?

A caveat: I attempted to apply 32 bit video to the footage and it crashed (windows message asking to send the error to MS and then it dissappeared). I attempted this again and it started to encode, but then the frames per second dissappeared and the preview was not moving. Also the progress was set at 0% and the time just kept climing it was set at 13 hours when I hit cancel. It was a 5 minute clip (using a velocity envelope and ctrl+drag from an hour long tape) I clicked cancel and waited for over 10 minutes and it never went back to where I could edit so I closed out of it via task manager.
I am currently rendering it out to 8 bit and it is working well.

j razz

Comments

Bill Ravens wrote on 10/2/2007, 8:08 AM
I've spent quite a bit of time, lately, trying to get my head around the best workflow, given the 32bit floating point math and Computer RGB/StudioRGB variables in Vegas. Here is what I have concluded:

1-Always use the Vegas WFM to monitor pluge bars(yes, this means inserting a test pattern at the head or tail of the footage.) If you use the Vegas NTSC test pattern with pluge, and you work in Computer RGB(CRGB) be sure to apply a level correction, SRGB to CRGB.
2-Throughout the workflow, work in 32 bit float, gamma 2.22, Computer RGB(monitoring and rendering intermediates). This has different effects, depending on which codec is being used. Glenn Chan has a good tutorial on codec specs. Cineform always wants to work in StudioRGB, Sony YUV wll work in Computer RGB in 32 bit mode.
3-Always monitor the pluge bars in the WFM. Make sure the WFM has the studio RGB radio button in the right position. If you have an external monitor, be sure it is also in the right mode(CRGB vs SRGB)
4-When all CC and editting is completed, and I'm ready for a "master", render to the output format. If the distribution media is the Web, render in Computer RGB output. If the distribution is television, render to Studio RGB. Whether I render in 8 bit or 32 bit, depends on the codec used.
5-Use Sony Levels FX to convert incorrect color spaces, i.e. CRGB to SRGB or SRGB to CRGB.
6-ALways be aware of whether the codec I'm using is CRGB or SRGB capable. Different codecs behave differently in 32 bit or 8 bit mode. The ONLY way to be sure is to monitor the WFM. Always be aware of the preview mode. Previewing in SRGB won't give an accurate display of colors and levels. CRGB is needed for correct monitoring on a computer.

I hope this helps. Color space in Vegas 8 is NOT trivial. One can unknowingly crush blacks, blow out highlights, make muddy blacks, or even distort final output coloring. Rendering to SRGB from CRGB, without first correcting the color space, will clip a lot of info. Rendering to CRGB from SRGB, without correcting the colorspace, will result in washed out images.

Vegas really, really, REALLY needs a tally light on the timeline, alerting the editor to the color space being used. It would also help, alot, if there was a tally light indicating what mode the WFM and preview window are in.
jrazz wrote on 10/2/2007, 8:21 AM
Thanks Bill.

I will take a look at those factors and work with what you have given me. Thanks for the time and informaiton.

Here is a question, does 32 bit even work with Cineform intermediaries (Packaged with Vegas)?

j razz
Bill Ravens wrote on 10/2/2007, 8:40 AM
According to Glenn Chan, the Cineform intermediate decodes and wants to see Studio RGB, regardless of the bit depth setting. It will output SRGB, as well.
GlennChan wrote on 10/2/2007, 1:47 PM
To answer the question...
1- You can try both paths, 8-bit and 32-bit/2.222. If the 8-bit is giving you banding, then switching to 32-bit may get rid of it.

The only thing to watch out for is that levels conversions are happening correctly in 32-bit/2.222. see
http://glennchan.info/articles/vegas/v8color/v8color.htm
In most cases you likely won't see a difference. But it depends on your source material and what you're doing with FX and image processing.

*If you see a dramatic difference in how the colors pop, it is likely due to a different levels conversion going on. Your video didn't really get better / you can do the same thing in 8-bit.

2- There is also the issue of the intermediary codec. I believe Vegas can only send 8-bit R'G'B' to Cineform. You'd be better off precision-wise rendering to uncompressed (NOT the SonyYUV codec); but right now I think there is a bug in that process if working with a 32-bit/2.222 project.


Hopefully this clarifies some things in understanding levels in Vegas...
a- The waveform monitor can be inaccurate. Whether it's accurate depends if it's setup correctly.
b- The video preview window can be inaccurate. The image may have the correct levels, but is displayed incorrectly / it's visually incorrect / looks wrong.
c- The settings for the waveform/video scopes do not change your underlying levels.