[lwneal]

This is a great use of a Makefile- notice how the audio file will only be downloaded if it does not already exist.

That said, if you're just looking for a simple one-liner you can paste into the terminal, my go-to is this one:

    cat *.jpg *.JPG *.jpeg | ffmpeg -r .5 -i - -vf "scale=w=1280:h=720:force_original_aspect_ratio=2,crop=1280:720" -y slideshow.mp4

There are many approaches described in [1], but none of them handle varying aspect ratios, which I find to be the most common problem when creating slideshows.

[1] https://trac.ffmpeg.org/wiki/Slideshow

[thosakwe]

I've started appreciating Makefiles a lot after using them more. It's honestly the simplest way to batch together tasks that might depend on each other (you can even use them to deploy applications).

[jancsika]

> This is a great use of a Makefile- notice how the audio file will only be downloaded if it does not already exist.

Is there a sane way to extend this out to check if a directory exists, and if not then download and unzip a file to create that directory?

The problem I always have with make and bash is that, for example, I only ever want two possible states-- the successfully unzipped directory or no state at all. And the more steps I add the more little state boogers my build system acquires (e.g., partial download, dangling zip file, etc.)

[gbuk2013]

Assuming directory “dir” and that “data.zip” archive will create that directory, this target will create the directory

  dir:
      wget http://.../data.zip
      unzip data.zip

[lipeltgm]

Nice to come across an appreciation of makefiles, often intimidating and frustrating to many but I feel it's a great use wrt video processing.