On 9/6/2017 9:13 AM, Rafal Lalik wrote:
I would also add one other suggestion for your consideration: If you
don't necessarily need all the other features of the Kdenlive Titler in
conjunction with your typewritter effect, you might consider making the
typewriter its own stand-alone service in MLT. I could see it as either
its own producer (which you would put on its own track and then
composite into your project) or a filter (which you would apply to a
clip or track as an overlay). The implementation could be a simple
wrapper around the qtext producer. The advantage of this approach is
that it could be used by more projects than just Kdenlive (Shotcut,
Flowblade, etc).
In the first place I was thinking about writing dedicated producer, but
then I looked closely into kdelivetitle. And I didn't found anything
specific (beside the name) in it that would link it directly to kdenlive
and permit to use with other software. The data are passed in xml format
which every 3rd party software can do, and what is returned is a
rendered image. So it is irrelevant whether the producer is called
kdenlivetitle or e.g. typewriter. (my initial idea was actually to
duplicate kdenlivetitle, rename it to typewriter) and add my features,
since the only difference is that the text is modified on frame basis,
all other features like font, size color, are exactly the same.
Am I wrong somewhere here?
In theory, yes, other applications could use the kdenlivetitle plugin.
But in practice, no other applications use it because:
* It is fairly complex and specialized in its interface.
* We pretty much give Kdenlive full control over the kdenlivetitle plugin.
Opinion of developers of the other software would be also helpful for me
Shotcut has its own titler based on HTML. Shotcut has no plans to use
the kdenlivetitle plugin. But if you created a "typewriter" plugin with
a simple interface (not all the XML stuff), I might be inclined to add
it to Shotcut.
Then filter issue. Isn't that the filter works already on the rendered
frame (image) so at this point it is to late to modify the text?
If you write a filter that is a "wrapper" for another filter, then you
can modify the encapsulated filter's properties before it writes to each
frame. The dynamictext filter is an example of this. It modifies the
"text" property of the qtext filter before each frame. Actually, this
would be a good model to follow if you go that route. The same principle
applies to producers - you can encapsulate a producer and modify its
properties before each frame.
I hope I don't sound like I'm trying to influence you. You should try to
work out whatever works best for your situation. But I do believe that
if you decouple your feature from the kdenlivetitle plugin it is likely
to receive wider adoption - if that is of interest to you at all.
~Brian
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