Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

ADM: Add MCA notes for IMF ADM Audio Track Files #75

Merged
merged 1 commit into from
Jun 14, 2024
+15 −0
Merged

ADM: Add MCA notes for IMF ADM Audio Track Files #75

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
15 changes: 15 additions & 0 deletions docs/audio_definition_model.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,8 @@ ADM, chunk_id=axml, RFC5646SpokenLanguage="en-GB", MCATitle="Default", MCATitleV
ADM, chunk_id=axml, MCATitle="No Commentary", MCATitleVersion="n/a", MCAContent="PRM", MCAUseClass="FCMP", ADMAudioProgrammeID="APR_1002"
```

_See below for guidance on writing `mca.txt` including specific IMF advice_

## SMPTE ST 2131 and SMPTE ST 2067-204

SMPTE ST 2131 defines a mechanism for mapping Resource Interchange File Format (RIFF) Chunks containing audio metadata to MXF files to augment MXF Sound Tracks. It defines additional MXF support specifically for the mapping and labeling of content described by Audio Definition Model (ADM) metadata (Recommendation ITU-R BS.2076) which is often carried in Broadcast Wave 64-bit (BW64) RIFF files (Recommendation ITU-R BS.2088).
Expand Down Expand Up @@ -169,6 +171,19 @@ The following extra properties can be used on any line where the `chunk_id` prop
* ADMAudioContentID
* ADMAudioObjectID

### MCA details for IMF ADM Audio Track Files

If an IMF Audio Track File is being created following Operational Mode A (see SMPTE ST 2067-204) then the following example approach to creating MCA is likely to be appropriate:

* Write one soundfield group (SG) "label line" for each audioProgramme element defined by the ADM metadata, with the audioProgramme ID put into ADMAudioProgrammeID
* Start each soundfield group (SG) "label line" with `ADM, chunk_id=axml`
* Set RFC5646SpokenLanguage and MCATitle to match the ADM metadata (see ST 2067-204 for details)
* RFC5646SpokenLanguage can be left out when appropriate
* RFC5646SpokenLanguage uses RFC 5646 language tags whereas ADM suggests the use of older ISO 639-1 or -2 codes so translation might be needed
- MCATitleVersion is always "n/a" unless there are special requirements
- Set MCAContent and MCAUseClass to properly represent the content of each audioProgramme
- Refer to SMPTE ST 377-41 for values and to https://www.imfug.com/TR/audio-track-files/ for examples (Note: the IMF UG document uses the same values but populates older MCA properties)

### MXF creation commandline for MCA

Example:
Expand Down
Loading