Review of JPEG 2000 subsection in AS-07

Review of JPEG 2000 subsection in AS-07
Revised to reference new terminology in ST 422:2013 (CF, 2/20/2014)
6.1.10.2.1 JPEG 2000 Essences and SMPTE ST 422 (informative)
This encoding, especially in the lossless or reversible mode, is typically selected by an archive
that is formatting or reformatting content as a part of its own pre-ingest or ingest activity, e.g.,
transferring content from a videotape carrier, or scanning film, and also prefers to store a
reduced-data file as compared to an uncompressed file.
The required carriage for JPEG 2000 essences in section 6.1.10.2.2 references the 2013 revision
of SMPTE ST 422, which included new standards for the GC Element for interlaced picture data,
summarized here. The revised standard refers to these as cases, and AS-07's two preferred cases
are, in order of preference:
 Case I1. Interlaced Frame Wrapping, 1 field per KLV Element. An essence container
that wraps JPEG 2000 compressed interlaced data with one field per KLV Element and
one frame per Content Package shall comprise one or more pairs of KLV triplets each of
which shall contain one JPEG 2000 codestream.
 Case I2. Interlaced Frame Wrapping, 2 fields per KLV Element. An essence container
that wraps JPEG 2000 compressed interlaced data with two fields per KLV Element and
one frame per Content Package shall comprise one or more KLV triplets each of which
shall contain two JPEG 2000 codestreams.
In addition, ST 422 includes a third option:
 Case F1. Field Wrapping, 1 field per KLV Element. An essence container that wraps
JPEG 2000 compressed interlaced data with one field per KLV Element and one field per
Content Package shall comprise one or more KLV triplets each of which shall contain
one JPEG 2000 codestream.
6.1.10.2.2 JPEG 2000 Essences and SMPTE ST 422 (requirements)
AS-07 encoders shall place JPEG 2000 picture essences in a SMPTE ST 422-compliant GC
Element. Interlaced picture data in JPEG 2000 encodings shall be formatted in accordance with
case I1, case I2, or case F1 as specified in SMPTE ST 422:2013.
Carriage of JPEG 2000 essences in a GC Element shall also employ SMPTE ST 422-compliant
tagging of the component (YCrCb) ordering sequence.
In addition to the wording above, we ask:
Do we continue to embrace case F1? I think the answer is yes because there is a manufacturer
whose system does it that way. If we accept F1, do we need to adjust the content integrity
wording? Perhaps no change is required if the wrapping is declared to be field wrapping, not
frame wrapping, as would be declared for I1 and I2.
Here's the wording we have now in our informative section:
Frame-wrapped picture may be progressive-scanned or interlaced. Picture data for
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progressive-scanned content will be represented as the V in a KLV triplet, and the
calculation of fixity is straightforward. Picture data for interlaced video will very often
be carried with the data from both fields represented as a single V in a KLV triplet. This
is the case for uncompressed video mapped according to SMPTE ST 384 and ST 377-1
(annex G.2.25), and also for JPEG 2000 compressed video case I2 (frame wrapping,
interlaced two fields per KLV triplet) mapped according to SMPTE ST 422:2013.
The exception to the general rule outlined in the preceding paragraph is the JPEG 2000
interlaced picture wrapping identified as case I1 in SMPTE ST 422:2013, where each
field is wrapped as a separate KLV triplet. In this case, AS-07 requires that the
concatenated V values for pairs of KLV triplets be hashed as one. AS-07 uses this
approach so that the integrity data for interlaced video is always at the frame (edit unit)
level. The same hash value would be calculated as from case I2, and this outcome
supports integrity monitoring if an essence is re-wrapped from I1 to I2 or vice versa.
And in the requirements section
6.6.2.2 CRC-32C values per KLV essence triplets
When required by a shim, AS-07 encoders shall calculate a Castagnoli CRC-32C Cyclic
Redundancy Code (IETF RFC 3385) value for every V or value data unit in the KLV
triplets that represent frame-wrapped essences, with the exception of interlaced JPEG
2000 that is wrapped according the case I1 specified in SMPTE ST 422:2013, the case in
which each field is wrapped as a separate KLV triplet. In the latter case, when integrity
data is required by a shim, AS07 encoders shall calculate the Castagnoli CRC-32C for the
concatenated values of the two Vs in the pair of KLVs.
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