0 IRE levels during transitions

John:

Thanks for that... I've been having problems with transitions expecially dissolves since FCP3 and now on FCP4, the problem still extists. Why does it do that to begin with? I'm going to try doing what you suggested.



Steven Escobar

G4 1.25MHz Dual MDD
1.25 RAM
IgniterX RT w/component
QT 6.03
OS X.2.8
FCP 4.02
Medéa drives 120G SCSI, 240G RT, 340 G RT
Igniter 6.0.3

[David Battistella] " hope Aurora support is reading this because this should not be the case at all.
"

This shouldn't be the case if you have your Igniter MJPEG or Uncompressed codec settings set to 0-255 and not 16-235. In the Audio/Video settings double click on your Sequence Preset, then select the Advanced button and then click Options. This should be at 0-255. Is it? If it's already set there let me know and I'll try to come up with another answer. But this should do it.


Michael Alberts
Ambidextrous Productions, Inc.

Michael, is there any reason to set it to 16-235?

Scott Davis

The "RGB Range" setting is global for the specific CODEC. It is not part of a sequence, capture, or render setting. If you click the QuickTime "Options..." button for an Aurora CODEC, you set it for ALL instances of that codec. If you click the "Load Factory Defaults" button on the Advanced tab of the Ignition PrefPane, you set ALL Aurora CODECs to 0-255. This is actually detailed fairly well in the OS X version of the IgniterX Manual. There are a few instances where you would want to use 16-235, but only when moving RGB data which is already scaled (ie: from a windows AVI file) into an FCP sequence.

- Mike

Yes.
What happens is this:
When you open an FCP sequence, Final Cut Pro does the following two operations:
1) Looks at the compression format for the sequence to determine if it is using a compressor that the current install supports. (For instance, you'd get a codec error if the sequence was created using an Aurora uncompressed format, but you were opening it on a machine without our board or codec.)

2) If the codec is okay, FCP hands 3 RGB frames to the compressor: a) a black slug. b) a single frame of SMPTE color bars c) the blue graphic that says, "unrendered". If the RGB range is set 16-235, the codec is being told that incomming RGB data is "pre-scaled", and that RGB values of 16 are to be mapped to YUV values of 16. Thus, RGB values of 0 get mapped to 0 in YUV space, resulting in a 0IRE black.

Now, inside a sequence, any empty portion of the timeline, or any placed black slug, results in FCP pumping out YUV result of the previously compressed RGB black slug. So, if you have the RGB range set to 16-235 when you open a sequence, all black or empty areas are output at 0 IRE.

Actually, the Range setting will only affect RENDERS from RGB space. All of your YUV-captured material should be fine.