[FFmpeg-user] encoding video from png diffs

[Joshua Grauman]

That's exactly what I need! Hadn't heard of the png_pipe option. I was 
thinking I might have to write a kernel module to create a bunch of /proc 
files or something! Thanks!

Josh

On Fri, 2 Sep 2016, Cley Faye wrote:

> 2016-09-01 19:31 GMT+02:00 Joshua Grauman <jnfo at grauman.com>:
>
>> I could of course generate all the pngs, but it would take up a lot of
>> space and I'm wondering if anyone knows of any creative way to do this?
>> Thanks!
>
>
> ​You could just do that. There is no need to write them anywhere though;
> you can pipe png sequences into ffmpeg directly (I create animations this
> way).
>
> I'm not familiar with vcdiff, but as long as you have a tool that produce a
> png on a standard output, you could loop over your diffs, piping the output
> info ffmpeg. Maybe you'll need a temporary variable storing the resulting
> png for the next step, but that will be held in RAM so no worries. Be
> careful if you do that though; binary data and shell script variables are
> not too friendly. I'd do that in python or another language.
>
> Once you have your script that output the sequence of png on it's standard
> output, you can pipe them to ffmpeg using '-' as the input name. Something
> like this:
> $ your_script | ffmpeg -f png_pipe -i - out.mp4
> Don't forget to specify framerate etc.
>
> (of course, if ffmpeg does support such format by itself, ignore this
> message; I'm not familiar with *all* the stuff ffmpeg supports either).
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