|dpp and AS-11 file delivery via agreed shims|
As the deadline for file based standards draws ever closer (October 1st) I've been looking at solutions for delivering files within the agreed AS-11 standard, and with so many courses being run in and around the BBC, its hard not to miss it.
So, while recently using VidChecker, I was rather alarmed to see a lot of errors being flagged on the RGB Gamut checks. So I had a quick look into this and they were just that... warnings.
Checking over dpps TechnicalDeliveryStandard document it mentions within section 2.3.2. the use of EBU Rec103 which addresses the RGB Gamut issue. The document states...
2.3.2 Tolerance of out of gamut signalsIn practice it is difficult to avoid generating signals slightly outside this range, and it is considered reasonable to allow a small tolerance, which has been defined as follows under EBU Rec103:
· RGB components must be between -5 % and 105% (-35 and 735mV)
and· Luminance (Y) must be between -1% and 103% (-7mV and 721mV)
Slight transient overshoots and undershoots may be filtered out before measuring, and an error will only be registered where the out of gamut signals total at least 1% of picture area. Many monitoring devices are designed to detect errors to this specification.
However, when looking at the VidChecker Shim (marked as DPP V4.1 HD AVC-I AS-11_MS) the EBU Rec103 has to be enabled to allow this information to be processed.
|Need to enable R103 to reduce the number of RGB Gamut errors flagged|
This obviously helps to reduce the number of errors brought to the end users attention but it then begs the question why this is not turned on as standard by dpp if it is quoted in their tech specs?
It would be nice to have a locked down shim for ALL dpp compliant systems so that people can ensure they are testing against a known standard across ALL platforms, rather than testing it against another shim that may well have been tweaked to fit someone else's needs or standards? In the scheme of things this doesn't really matter as this does not affect the file from a failure point of view, but does have a dramatic impact on the number of warnings created by the system.
That said, setting a standard is not such any easy thing to do when video codecs are involved, so I think the dpp standard is a fair stab at something that will always be hard to please everyone, especially in the fast paced technology area that is video post and broadcast. You need to remember that the standard is not only addressing Technical needs but also a change in mind set that needs to be embraced by both Post Production houses and the Productions themselves, which can only be done via education and solution implementation.
More info can be found on the Digital Production Partnership web site or you can follow them on twitter @ukdpp