Differences

This shows you the differences between two versions of the page.

--- hdr_uhd_signalling [2016/11/21 14:41] – [AVP Modes] walkeradmin
+++ hdr_uhd_signalling [2023/03/09 22:35] (current) – external edit 127.0.0.1
@@ Line 6: / Line 6: @@
 \\
 ==== 6.1.9 Signalling Transfer Function and Colour Space ====
-\\
 \\
 The colour space and transfer function (SDR or HDR) are typically signalled in the VUI of an
@@ Line 34: / Line 33: @@
 {{:hdr_menu.png?150|}}
 \\
+\\
+The above menu allows the HDR type to be hard coded in the TS by the AVP. The options are fairly obvious except the <color red>HDR HLG10 (SDR in VUI)</color> option.
+\\
+\\
+==== HDR HLG10 (SDR in VUI) ====
+\\
+What HDR HLG10 (SDR in VUI) means is that in the VUI we signal that the stream is SDR, this is so that non HDR screens will use the standard transfer function for the luma scale (100 NITs). But the stream is actually a HDR stream, and newer 4K televisions will read the VUI, see it is signalled as SDR, then they will check the SEI, and see if the stream has been signalled as HDR, and so then they can decode as HDR.
+\\
+\\
+This only works with HLG HDR streams, PQ10 does not work the same. HLG has built in backwards compatibility that relies on the HDR information being at the end of the transform where SDR TVs will ignore it. PQ10 (Dolby Vision) has a dual layer approach for backwards compatibility. There is an SDR stream with supplemental information that a HDR decoder combines with the SDR to create HDR outputs. This dual layer approach adds 20%-30% overhead. PQ10 also has a single layer approach for HDR, but with no backwards compatibility.
+\\
+\\