HDMI: Handling of reserved values

[LigH]

According to the HDMI 1.3a specification (http://www.microprocessor.org/HDMISpecification13a.pdf) (document page 95, PDF page 111), even in RGB full range, the valid range for 8 bit per component video is 1-254. The reserved values 0 and 255 belong to Timing Reference Signals.

How is this handled technically? Will super black and white video content be clipped to the valid range before submission (e.g. from the PC desktop to the PC monitor)? Is it certain that digitally captured HDMI video will be slightly limited even in RGB "full range" mode, thus not bit-exactly "lossless"?

[pandy]

According to the HDMI 1.3a specification (http://www.microprocessor.org/HDMISpecification13a.pdf) (document page 95, PDF page 111), even in RGB full range, the valid range for 8 bit per component video is 1-254. The reserved values 0 and 255 belong to Timing Reference Signals.

How is this handled technically? Will super black and white video content be clipped to the valid range before submission (e.g. from the PC desktop to the PC monitor)? Is it certain that digitally captured HDMI video will be slightly limited even in RGB "full range" mode, thus not bit-exactly "lossless"?

For RGB You have two modes Full (default for DVI and only allowed - optional for HDMI) and Limited Range.
In Full Nominal Black level is 0 and Nominal White is 255, in Limited Nominal Black level is 16 (and valid range 1) Nominal White is 235 (valid range 254). - Same principle as in 601/656.
For YCbCr Full Range is not allowed thus same principle as for Limited Range in RGB mode - 16-235 are Nominal and 1-254 are Valid.
As Source and Sink are designed in same way - there is no loss (i.e. Source can't send 0 - 255 video - it must be transformed to 1-254 and usually it is transformed to 16-235).