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w3c / PNG-spec

Maintenance of the PNG specification
https://w3c.github.io/PNG-spec/
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Latest H.273 is not free #428

Closed svgeesus closed 3 months ago

svgeesus commented 4 months ago

From the PNG spec, the reference to H.273 points to

https://www.itu.int/rec/T-REC-H.273

From that page, there is a link to H.273 (07/21) which still works and is free. But there is also a link to a new version, H.273 (09/23) which says Document restricted to TIES users [ITU-T].

Does anyone know, is that a temporary situation (that version is described as prepublished,) or is this a new, non-free policy coming into effect?

svgeesus commented 4 months ago

This page says H.273 2021 is superseded and the 2023 version is "in force".

I have found a description of the changes between 2021 and 2023, which does not seem it impacts PNG as it is solely for non-RGB formats:

This revised Rec. ITU-T H.273 adds the specification of code point identifiers for YCgCo-R colour representation with equal luma and chroma bit depths and for the colour representation specified in SMPTE ST 2128. The new code points for YCgCo-R are referred to as YCgCo-Re and YCgCo-Ro, where the number of bits added to a source RGB bit depth is 2 (i.e., even) and 1 (i.e., odd), respectively. SMPTE ST 2128 specifies a colour representation referred to as IPT-PQ-C2 This Recommendation was developed jointly with ISO/IEC JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information, and Rec. ITU-T H.273 is maintained as technically aligned twin text with ISO/IEC 23091-2. The changes specified in this version correspond to the technical content of a not-yet-published future (third) edition of ISO/IEC 23091-2.

digitaltvguy commented 4 months ago

Superseded and in-force but not available to general public yet without a TIES login. I’m not sure when it will be fully released (pre-published).

svgeesus commented 3 months ago

(whoops)

ProgramMax commented 3 months ago

In today's meeting, we discussed this. Our understanding is that there is a short window where it is not free because a new edition is being released. But it is still generally free. So I'm closing this issue.