Attach is a patch that makes MLT aware of metadata (avformat and vorbis
producers). Basically, it stores metadata in the producer properties. This
can be quite usefull for Kdenlive.
Let me know if you agree with the idea of having metadata read by MLT, and if
the patch is ok, I can commit it.
From: Dan Dennedy <dan@de...> - 2006-12-11 23:41:03
On Sunday 10 December 2006 4:40 am, jb wrote:
> Hi everyone.
> Attach is a patch that makes MLT aware of metadata (avformat and vorbis
> producers). Basically, it stores metadata in the producer properties. This
> can be quite usefull for Kdenlive.
> Let me know if you agree with the idea of having metadata read by MLT, and
> if the patch is ok, I can commit it.
Yes, this is a good idea, but the patch needs a little work. One of the
problems we have in MLT is property naming - conflicts and meaning.
Therefore, we have started using a dot notation for qualifying property names
to create namespaces. None of this is documented at the moment. For this
patch, you _must_ qualify the property names using the prefix "meta." but
preferrably "meta.attr.". Then, you might even go so far as making the
metadata attribute name be a stem for a set of possible values. For example,
the textual value is merely one attribute of the metadata item. There could
also be a content-type and charset, for example.
I encourage you to take a look at the data_show filter along with the
mlt/demo/mlt_attributes. MLT contains a templating system that is a little
complex and undocumented. You can, for example, create a titling template.
Then, you can feed metadata into the template's place-holders. The existing
templates - see src/modules/feeds - establish a precedent for using the
suffix ".markup" for the content of the metadata property name. For example,
your filter could set meta.attr.author.markup. (I am thinking "content"
instead of "markup" would have been a better precedent.")