[ogg-dev] Metadata

[Ralph Giles]

On 13-07-22 11:19 AM, Brendan Bolles wrote:
> Hey everyone, according to Wikipedia's 4-year-old information, there is no standard for putting metadata into an Ogg file.  That metadata must be included in the codec.

That's correct in that there's no container-level metadata. The
'mapping' specs for various sets of codecs embedded in Ogg describe how
metadata is stored.

> For example, what if I want to make a Theora movie and include information about the color space or embed an ICC profile?

Theora only supports two fixed colourspaces--defined in the spec--and
'unspecified'. There's generic metadata, so you could do something
custom with a base64-encoded ICC profile and an undefined colourspace
flag if you want to track this, but we generally discourage that. Theora
is a distribution format; it's best to convert to one of the fixed
output colourspaces at encode time if care about calibration.

See section 4.3 of http://theora.org/doc/Theora.pdf for details.

> Or can I include general textual information, like copyright?  What about timecode?

You can include standard tag information in theora videos like title,
author, copyright and license; just put them in the theora metadata
header. I'm not aware of a convention for timecode (if you mean timecode
offset of the first frame; theora is a fixed-framerate codec so there's
no need for per-frame timecode) but you could make something up for your
application, or use the 'Basetime' of the skeleton spec.
http://wiki.xiph.org/Ogg_Skeleton_4

HTH,
 -r