JPH output: ftyp compatibility list omits the 'jph ' brand (lists only 'jp2 ')

[flamsens]

Summary

When grok writes a High Throughput JPEG 2000 (.jph) file, the File Type box
(ftyp) sets the major brand correctly to jph but its compatibility
list (CL) contains only jp2 — it does not include jph . Per ISO/IEC
15444-15, a conformant JPH file's compatibility list should include the jph
brand. As a result, strict validators (e.g. jpylyzer) report the file as invalid,
even though it is otherwise well-formed and decodes correctly (including by grok's
own grk_decompress).

Version

grok v20.3.5 (release tarball), built from source, amd64.

Steps to reproduce

# any input image
grk_compress -i input.png -o out.jph -n 7 -c "[256,256]" -b "64,64" \
  -p RPCL -S --tile-parts R --plt --tlm -M 64

pip install jpylyzer            # >= 2.2 (has HTJ2K/JPH support)
jpylyzer --format jph out.jph

Observed

jpylyzer reports the file invalid with a single failing test:

<isValid format="jph">False</isValid>
...
<compatibilityListIsValid>False</compatibilityListIsValid>
...
<fileTypeBox>
    <br>jph </br>      <!-- major brand: correct -->
    <minV>0</minV>
    <cL>jp2 </cL>      <!-- compatibility list: only 'jp2 ', missing 'jph ' -->
</fileTypeBox>

The .jph decodes fine via grk_decompress, so this is purely a file-format
conformance issue in the JPH ftyp writer.

Expected

The ftyp compatibility list of a .jph file should include the jph brand
(in addition to, or instead of, jp2 ), so the file passes ISO 15444-15
conformance validation.

Notes

Appears to be a one-line addition in the code that builds the JPH File Type box's
compatibility list.

[boxerab]

Thanks for the detailed bug report - now fixed.