ACES Metadata File Development

Instead of RRT use referenceRenderingTransform

Oh right, I don’t really mind the short forms, especially because they have been around for a while people know them.

That said now that you mention it seeing ODT and OutputTransform is somehow not very elegant and using OT certainly not very clear.

In order for AMF to be really interoperable (for example, embedding AMF elements into an IMF package as part of either a SCM .xml or an ISXD ,mxf file), clear indications on the AMF namespace and its usage in AMF-specific element names, should be clearly and unambiguously described.

I am referring to clear indications. Is amf the chosen namespace, or wouldn’t it be better to use one namespace aces for all ACES-related XML files (including CLF) ?

Also, whatever the namespace is chosen, it should be mandatory in all AMF characteristic namspaces. Therefore, it’s <amf:RRT> or <amf:referenceRenderingTransform>, not <RRT> alone.

I just picked amf. Happy to change it if that makes sense. Note CLF is not ACES only. Hence, I don’t think it makes sense to make the CLF tags part of a aces namespace.

Is this best practice? I’m not an xml expert. Would it just be reflected as a change in the example, or is there as way to require the namespace via the xsd?


Hi Alex.
Strictly speaking, good XML syntax requires that each element has its own namespace prepended.

In real-world, I’ve seen XML files where, after assigning a namespace to an element, that namespace becomes the default for all of its children, which are then entered without namespace – unless some children are given specific, different namespace specifications – in which chase the latter have precedence.
But, in such a case, problems may arise if the AMF embeds chunks from other XML schema (e.g. CDL, CLF, etc.) or -vice versa- AMF is embedded into a bigger XML file. This latter case may happen if AMF is embedded as part of:

  • SCM or ISXD components of IMF packages (which I’d love to see in the ADSM for binding AMF metadata to an IMP)
  • digital signature wrapping the AMF for sealing its integrity and authorship
  • a video processing application’s own XML-based project file (e.g. R&S Clispter, FinalCut Pro, NUKE, etc.)

Just look at how the CPL component of any SMPTE-compliant DCP looks like, particularly at the usage of elements from the XML Signature standard, which are usually assigned the namespace ds.

Let me clarify a single point though. The namespace name (e.g. either amf or ampas) is just a convention. The real namespace is the URI reference to the XML schema file given by the xmlns attribute value; you can define any namespace name as long as this is consitently used throughout the same XML document.

Happy to have a conversation to you for more clarifications.

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