[AVTCORE] Francesca Palombini's Discuss on draft-ietf-avtcore-rtp-vvc-16: (with DISCUSS and COMMENT)

[Francesca Palombini via Datatracker <[e-mail]>]

Francesca Palombini has entered the following ballot position for
draft-ietf-avtcore-rtp-vvc-16: Discuss

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DISCUSS:
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# ART AD Review of draft-ietf-avtcore-rtp-vvc-16

cc @fpalombini

Thank you for the work on this document.

I have two DISCUSS points - hopefully easy to resolve - and a few non blocking
comments, but answers will be appreciated.

Francesca

## Discuss

### DONL and NALU size in figures 5 and 6

Section 4.3.2:
```
   The first aggregation unit in an AP consists of a conditional 16-bit
   DONL field (in network byte order) followed by a 16-bit unsigned size
   information (in network byte order) that indicates the size of the
```
Which indicates DONL to be a 16-bit field, but in the figure 5 DONL appears to
be 24 bits.

```
   An aggregation unit that is not the first aggregation unit in an AP
   will be followed immediately by a 16-bit unsigned size information
   (in network byte order) that indicates the size of the NAL unit in
```

Same for the NALU size: 16 bits in the paragraph above, but 24 bits in figure 6.

### IANA Media type review request missing

As specified by RFC6838, it is strongly encouraged to post the media type
registration to the media-types mailing list for review (see
https://mailarchive.ietf.org/arch/msg/media-types/3_DukpPWrpkTXO-zynjJlShtC1w/
for an example of a  registration review). Is there any reason this was not
done here? If not, please post to the media-types mailing list, and I will
remove the discuss with no objections raised in a week or so.


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COMMENT:
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## Comments

### Values from \[VVC\] undefined

In section 3.1.1, there are a number of values that are not defined:  GDR_NUT,
CRA_NUT, IDR_W_RADL, IDR_N_LP. I understand these come from \[VVC\] and are
reported as is, however they make the text harder to parse since to reference
to these values is given.

### Wrong reference

Section 4.3:
```
      header.  This payload structure is specified in Section 4.4.1.
```
4.4.1 should be 4.3.1.

### sprop-max-don-diff

sprop-max-don-diff appears first in section 4.3.1 - it would be good to add a
reference to 7.2, where its meaning is defined.

### Base 64

In Section 7.2, Base64 is used - please specify if the encoding follows "Base
64 Encoding" (Section 4) or "Base 64 Encoding with URL and Filename Safe
Alphabet" (Section 5) of RFC 4648. (This can easily be done in one sentence,
rather than repeated everytime base64 is mentioned).

## Notes

This review is in the ["IETF Comments" Markdown format][ICMF], You can use the
[`ietf-comments` tool][ICT] to automatically convert this review into
individual GitHub issues.

[ICMF]: https://github.com/mnot/ietf-comments/blob/main/format.md
[ICT]: https://github.com/mnot/ietf-comments