Thread: [Mlt-devel] Automated playing of slideshows and clips
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From: klaas.holwerda <ng...@kl...> - 2010-07-23 17:00:32
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Hi, (Only heard about kdenlive and MLT a few days ago ). Know how to use mencoder, but realize that what I really needed is melt/MLT. So i started reading API, concepts etc., and i think i get it more or less ;-) I hope this is oke to ask some questions here, i could not find other means, if not appreciated, let me know. I have a list of images and clips, which need to be played automatically in a loop on a client (after downloading them from a server). Display time for the images is know, and same for the video clips. Of course I like a nice transition in between. Besides that there will be a ticker (walking text string) at the bottom of the screen, which I do not yet know how to solve. All the data is given to the client as XML document from the server, and updated regularly. My first idea is to have a melt XML file (automatically generated by me), which is then rendered and/or played by melt. Since adding transition and all that is not so easy, I think of using kdenlive, to more or less give the XML I need for that. e.g. making something close to what I need, and use that as a template. Question: - How can I get the MLT XML from kdenlive (or is it in its project file)? - How to I achieve looping with melt (e.g. the XML file needs to played in a loop) - can i easily display an list of images several seconds each? - What is the best way to generate walking text? Should I make/generate a separate clip, and composite it on to the rest? Or is there something more advanced available. Thanks for some ideas, and even more for all this great stuff! Klaas |
From: Dan D. <da...@de...> - 2010-07-23 17:58:39
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On Fri, Jul 23, 2010 at 10:00 AM, klaas.holwerda <ng...@kl...> wrote: > Hi, > > (Only heard about kdenlive and MLT a few days ago ). Know how to use > mencoder, but realize that what I really needed is melt/MLT. So i > started reading API, concepts etc., and i think i get it more or less ;-) > I hope this is oke to ask some questions here, i could not find other > means, if not appreciated, let me know. > > I have a list of images and clips, which need to be played automatically > in a loop on a client (after downloading them from a server). > Display time for the images is know, and same for the video clips. Of > course I like a nice transition in between. > Besides that there will be a ticker (walking text string) at the bottom > of the screen, which I do not yet know how to solve. All the data is > given to the client as XML document from the server, and updated regularly. > > My first idea is to have a melt XML file (automatically generated by > me), which is then rendered and/or played by melt. > Since adding transition and all that is not so easy, I think of using > kdenlive, to more or less give the XML I need for that. e.g. making > something close to what I need, and use that as a template. good idea > Question: > > - How can I get the MLT XML from kdenlive (or is it in its project file)? It is in the project file. Kdenlive project files can be played directly with melt, and in fact Kdenlive runs melt as a child process to render projects. > - How to I achieve looping with melt (e.g. the XML file needs to played > in a loop) -repeat N That does not let you loop indefinitely. If you need indefinite, there is an eof property for mlt_playlist that can be set to loop, but I have to workout exactly what changes in the XML. Otherwise, some high repeat value like 999999 might work. > - can i easily display an list of images several seconds each? yes, see demo/mlt_slideshow in the mlt source tree. Kdenlive can also generate this using a slideshow clip. One caveat with this this technique is that it processes all files matching a filename extension in a folder. Also, there appears to be some recent regression in the transitions that I need to address. You might be best off to generate playlist XML from a list. > - What is the best way to generate walking text? Should I make/generate see demo/mlt_ticker. The caveat here is that composite does not yet do sub-pixel positioning via interpolation, and to make matters worse, because it operates in the yuv422 image format, the precision of the positioning is even pixels instead of pixel. Basically, this means it is not real smooth right now. Interpolation was recently added to the affine transition, which also does compositing, so you might be able to get it work using that. > a separate clip, and composite it on to the rest? Or is there something > more advanced available. You do not need a separately rendered video clip, but you do need a producer (pango, svg, or kdenlivetitle) and a transition (composite or affine). Alternatively, to make expression or resource management easier, you can use the watermark or affine filters and supply one of these producers as a property to the filter for its "background." > Thanks for some ideas, and even more for all this great stuff! > > Klaas > -- +-DRD-+ |