[Kdenlive-devel] Support for more clip types

Till Theato root at ttill.de
Mon Feb 18 18:00:01 UTC 2013

Hash: SHA1

On 02/18/2013 05:05 AM, Brian Matherly wrote:
> Hi,
> I've been inspired to add support in Kdenlive for more of the
> producers in MLT. Right now, you can make color clips and you can
> use the generator plugin to create a noise and count down clip. But
> MLT exposes some other producers: like the Frei0r test patterns.
> And I'd like to add some audio test tone synthesizers.
> I've been researching this part of the Kdenlive code and I found
> that there are two ways that MLT producers are exposed: "clips" and
> "generators". My frist inclination was to make generators for all
> producers. But I don't care for the fact that you end up with
> another MLT file to manage with the project and that the generated
> clips can not be extended on the timeline by clicking and draging.
> It seems to me that it would be better if the clips were
> implemented like the color clip. But that would require more code
> in the clip manager - and I don't know how scalable that would be.
> It would sure be nice if the clip manager supported a generic MLT
> wrapper architecture like the effects stack. That way, when new
> producers are added in MLT, Kdenlive could adopt them just by
> adding a new XML file.
> I'm willing to put in some time to make the clip manager more
> generic. But I'd like to hear your thoughts on that first. If you
> aren't excited about having changsd made in there, then i would be
> content to just implement more generator plugins.

Hey Brian,

in case you do not need this feature immediately you might want to
have a look at the refactoring branch. There we have
AbstractProjectClip (src/core/project/abstractprojectclip.h),
AbstractClipPlugin and AbstractTimelineClip which can be subclassed
for different types of clips/producers (See src/plugins/cliptypes).
Currently the implementations of image (qimage/pixbuf) and video
(avformat, should be renamed to av) are started. These two cannot be
made more generic because of things like exif data or the requirement
to have different base producers for different tracks (audio issues
with avformat).

But especially all the "generators" which do not use an input file
could probably be handled by one single clip type plugin. For example
by making using XML files similar to the ones used for effect
descriptions. Just as you proposed.
What do you think?


> Thanks for your thoughts,
> ~Brian

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