On Fri, May 6, 2011 at 9:38 PM, Brian Matherly <[email protected]> wrote:
> Nice work. It looks like you knew I'd be asking for this. I've spent some 
> time playing with data_show. It looks promising. A couple of questions:
>
> 1) Is there any way to apply the meta.attr.* properties to the playlist, or 
> the entire timeline? The only way I  can make it work is to add the meta 
> properties to every producer. If someone wants the timecode to apply to the 
> entire output, it is a bit cumbersome to apply the properties to each 
> producer.
>

If you are using melt, see the -group option.  Another way is to
include a xml playlist file as a clip within another composition where
the attributes are added. Otherwise, a tool that uses mlt can apply
the properties automatically according to its rules taking away the
tedium.

> 2) Can you show an example of how to use the data_feed filter? I can't seem 
> to get it to do anything.

The data_feed is applied automatically to producers. See
core/loader.ini as used by the loader producer, which is the default
"super" producer. Likely there are ways to use data_feed more
manually, but I do not know it so well. Just do not assume all
services have a visible or audible effect. They can also coordinate
things (loader) or do things with data/properties.

> 3) It appears that MLT has properties for the file name - which I think would 
> be useful as an overlay. How would I go about overlaying the file name for 
> all files in the track?
>

Currently, the data_show only does things with meta.attr. properties
and special keywords 'timecode' and 'frame'. Of course, some
tool/script could process a composition or mlt object model and copy
the filename to a meta.attr.

> 4) Ultimately, I want to overlay the file creation date. That information is 
> not currently a property that is available within MLT. The application (or 
> user) would have to add the creation date to the producer for each file. This 
> isn't too difficult for an application, but it is cumbersome to do by hand. 
> Do you have any interest in having MLT get the file creation date and make it 
> available within the framework? Or is that a task best left to the 
> application?
>

That is something that could be added to a producer (avformat would
cover most cases except still images), or it can be the responsibility
of a tool. I dunno. The avformat and image producers are already very
complicated, and I hesitate to give them more duties. A thing to keep
in mind is that this list could grow, and one needs to also think
about date strings formats. Mlt does not have a native date type to
which it can convert to and from string. Another thought is one could
learn to author comps in Python or other scripting language with mlt
binding where you can use functions to lookup things and pass their
result to an mlt object. In a bash-like shell you can embed a
command's output into melt options with $(). It does seem like you may
want move up to scripted generation of mlt xml and/or melt command
lines.

+-DRD-+

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