| Re: animated gif speed [message #87585 is a reply to message #87584] |
Sat, 15 February 2014 16:15   |
Paul Levine
Messages: 29
Registered: February 2008
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Junior Member |
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On 2014-02-15 23:53:13 +0000, David Fanning said:
> Paul Levine writes:
>
>> So far, when it comes to animations, my needs have been very simple,
>> and I have been able to accomplish what I want (using new graphics)
>> with the /APPEND keyword to the write method and the GIF file suffix,
>> which gives me a nice little animated gif.
>>
>> Now I would like to be able to control the "playback speed" of the
>> animated gif, which if I understand correctly, is basically a delay (in
>> 1/100th of a second) specified for each frame that it waits before
>> advancing to the subsequent frame. But it seems my rather simple method
>> is too limited for this, as there is no DELAY_TIME keyword in new
>> graphics as there is in the WRITE_GIF procedure.
>>
>> I have looked at http://www.idlcoyote.com/tips/howmovie.html but as I
>> am an IDL neophyte with a less-than-rudimentary understanding of how to
>> use objects, it will take some substantial learning on my part to
>> figure out how to actually implement any of that advice. Of course,
>> learning is never a bad thing, but with the limited time I have, I am
>> trying to figure out whether I would be better served learning the ins
>> and outs of the IDLffVideoWrite object (and object oriented programming
>> in general) or whether there is an easier way to take the output of my
>> already-existing function graphics and create an animated GIF (or
>> otherwise) with control over the playback speed
>
> I'm guessing it might take 5 or 10 seconds to learn how to use
> IDLffVideoWrite, assuming you have GIF files sitting around somewhere.
>
> Cheers,
>
> David
Thank you for the suggestion. Though I must admit, I'm unsure how
having GIF files will help with learning about IDLffVideoWrite; doesn't
the IDLffVideoWrite object deal directly with movie files (AVI, MP4)
rather than GIF files?
It seems the conceptual hurdle I am having a hard time getting over is
not the actual use of IDLffVideoWrite itself, but how to get my data in
the form that feeding it to IDLffVideoWrite::Put will give me a video
that appears how I want it.
My data is a sequence of 2D floating point arrays; I am using the
function graphics (am I supposed to call them "new" graphics?) to
byte-scale the data to a color table, warp it to a map projection, draw
continents, map grids, and color bar, etc. Is the trick simply to
follow the equivalent steps from
http://www.idlcoyote.com/gallery/avi_movie.pro where each frame is
created (with map grid, continents, etc.), saved to a file, then read
back in from the file to be loaded into the video stream?
Thanks!
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