Add SMPTE ST 2067-201:2026 IAB Plugin Level 0 support: MCA Content/Use Class, IABMaxObjectCount, IABChannelSubDescriptor11 - #169
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- Replaced the exact-match test (iabAudioDescription != 0x80) with a proper MSB test (iabAudioDescription & 0x80), so any value 0x80–0xFF with the top bit set (e.g. 0x81, 0xC0) correctly permits AudioDescriptionText — matching ST 2067-201 Annex E.2.5 and ST 2098-2 §10.3.13. - Made it bidirectional: text present but MSB clear → rejected; MSB set but text absent → rejected (the item must be present iff the MSB is set). - Fixed the stale comments (line 145 and the wrong "0x08" on line 150) and cited the governing spec clauses.
Added full support for the two new MCA items the 2026 revision adopts from ST 377-4:2021 / ST 377-41:2023.
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Summary
This PR extends the AS-02 IAB implementation to cover SMPTE ST 2067-201:2026
(IAB Plugin, Level 0) and the associated ST 377-41 MCA labeling items. It adds
the new structural metadata to the library, wires it through the
AS_02::IAB::MXFWriter, and exposes it in the command-line tools. All newwriter parameters are optional with backward-compatible defaults, so existing
callers are unaffected.
Changes
New / extended structural metadata (
Metadata.h/.cpp,MDD.h/.cpp)MCAContentandMCAUseClassoptional properties to
MCALabelSubDescriptor(read/write/copy/dump),per SMPTE ST 377-41:2023 (ST 2067-201:2026 §5.10.3). New item ULs
registered in the MDD table.
ui16_titem onIABEssenceDescriptor(ST 2067-201:2026, Table 3).InterchangeObjectsubclass(ST 2067-201:2026, Annex E) with items
IABBedMetaID(ui32),IABChannelID(ui32),IABAudioDescription(ui8) and optionalIABAudioDescriptionText(UTF-16). Includes the set key + item ULs, andregistration of an object factory so the descriptor is parsed on read.
Writer (
AS_02_IAB.h/.cpp)MXFWriter::OpenWritegains three optional trailing parameters:write_max_object_count,max_object_count, and a vector ofIABChannelSubDescriptors. When supplied,IABMaxObjectCountis set onthe essence descriptor and the channel subdescriptors are cloned (with
fresh InstanceUIDs) and linked into the essence descriptor's
SubDescriptors list.
SetEditRateis now applied after descriptorsetup and
SetPrimerLookupis wired to the header primer.Command-line tools
as-02-wrap-iab— new options:-m <count>— IABMaxObjectCount.-c <bedMetaId>,<channelId>,<audioDescription>[,<audioDescriptionText>]— add an IABChannelSubDescriptor (repeatable).
-C <mca-content>/-u <mca-use-class>— MCA Content / Use Class.Input is validated before writing:
(bedMetaId, channelId)pairs must beunique, and
AudioDescriptionTextmust be present iff the MSB (0x80) ofAudioDescriptionis set (ST 2067-201:2026 Annex E.2.5 / ST 2098-2§10.3.13).
as-02-info— reportsIABMaxObjectCountwhen present.as-02-unwrap— IAB frames are now written out to.iabfiles(honoring
file_prefix,number_width,no_write_flag, andfb_size),replacing the previous hexdump-only path and the hardcoded 24000-byte
frame buffer capacity.