Manim: Reactivation of the gif export

[kolibril13]

There are still the optional arguments:
"-i", "--save_as_gif" for saving scences into gif.
This feature was added to 3b1b's repo here https://github.com/3b1b/manim/commit/c42ae8a55bb2f1ef8259a719f17eaf519c46f3f8
and removed here https://github.com/3b1b/manim/commit/61bb4944fad2ee889145bbf8a3253fb07c71bf7d where Grant wrote:

It seems strange to me that the "-c copy" line breaks things when you're trying to make a gif, is there a more natural way to address whatever the underlying issue is here? In a perfect world, we should be able to make things so that if you set "movie_file_extension" in the SceneFileWriter to ".gif", it figures out the settings it needs and renders the gif. Having a bunch of extra attributes for gifs strikes me as redundant.

So my idea would be to add to manim/scene/scene_file_writer.py something like

if self.save_as_gif:
            os.system("ffmpeg -i PATH_TO_VIDEO/input.mp4  output.gif")

This way, the video get's first rendered to mp4 and then to gif, but I think that's the most forward option.

[Tony031218]

This is indeed the best solution for exporting gifs. I think it also needs to support controlling the bit rate and setting the default bit rate.
In some cases, high-resolution and high-bitrate gifs may not look good.

[kolibril13]

Here is a first idea of the implementation:

from manim import *

class WriteStuff(Scene):
    def construct(self):
        dot = Dot()
        circ = Circle()
        squ = Square()
        self.play(Write(dot))
        self.play(Write(circ))
        self.play(Write(squ))

from pathlib import Path
if __name__ == "__main__":
    scene_name= "WriteStuff"
    script = f"{Path(__file__).resolve()}"
    os.system(f"manim -i -l -p -c 'BLACK' --video_dir ~/Downloads/ " + script + " " + scene_name)
    os.system("ffmpeg -i ~/Downloads/" + scene_name + ".mp4" + " "+  "~/Downloads/"+ scene_name + ".gif")

with an adjusted output dir in scene_file_writer.py:

  # Output directories and files
    def init_output_directories(self):
        module_directory = self.output_directory or self.get_default_module_directory()
        scene_name = self.file_name or self.get_default_scene_name()
        if self.save_last_frame:
            image_dir = guarantee_existence(os.path.join(
                dirs.VIDEO_DIR,
                #module_directory, #removed here
                #scene_name,
                #"images",
            ))
            self.image_file_path = os.path.join(
                image_dir,
                add_extension_if_not_present(scene_name, ".png")
            )
        if self.write_to_movie:
            movie_dir = guarantee_existence(os.path.join(
                dirs.VIDEO_DIR,
                # module_directory, #removed here
                # scene_name,
                # self.get_resolution_directory(),
            ))

[leotrs]

I'm not sure I follow your original post. Are you saying the -i flag is broken? If so, yes we should fix it. Grant's comment is about the -c flag so I'm not sure how that is related.

[huguesdevimeux]

@leotrs Yes, --save_as_gif seems to be broken (as it is not used in the code at all).

I think that the idea of Grant was to actually use a flag to set the extension of the movie file generated (maybe this is the -c that he is talking about) , and then to use this flag with gifto create a .gif.

I am not sure that this is the correct way to do that. We should (re ?) implement --save_as_gif.

[leotrs]

Agreed, let's just implement -i for now. Any takers?

[yoshiask]

Sounds good to me.

I also want to point out that having a flag that changes the file type of the output would be useful for add-ons. For example, my PowerPoint add-on adds the --save_as_pptx flag, which could be removed in favor of adding .pptx as a valid output format. E.g. `-c [ mp4 | mov | gif | pptx | ... ]

[Aathish04]

Agreed, let's just implement -i for now. Any takers?

I re-added it in the fix-gifs branch some time ago.

It can be merged, unless it can be implemented in a better way.

[leotrs]

@Aathish04, I just came across this again when working on #98. Any quick fixes we can PR here? If I understand this part of the code correctly, it seems the member gif_file_path is correctly set in scene_file_writer.py (or at least it's correctly set in the latest commit of #98...), but it's just never used.

[Aathish04]

@leotrs Yeah, I just made one.