Source of H.273

[[H.273]]

- H.273 : Coding-independent code points for video signal type identification
// --  https://www.itu.int/rec/T-REC-H.273-201612-I/en
--  https://www.itu.int/rec/T-REC-H.273/en
---   https://www.itu.int/rec/T-REC-H.273-202107-I/en

- [[CICP]]: Coding-independent code points

* コーデック [#we5a018d]

- [[H.265]]