SceneFileWriter

Qualified name: manim.scene.scene\_file\_writer.SceneFileWriter

class SceneFileWriter(renderer, scene_name, **kwargs)

Bases: object

SceneFileWriter is the object that actually writes the animations played, into video files, using FFMPEG. This is mostly for Manim’s internal use. You will rarely, if ever, have to use the methods for this class, unless tinkering with the very fabric of Manim’s reality.

sections

used to segment scene

Type:

list of Section

sections_output_dir

where are section videos stored

Type:

pathlib.Path

output_name

name of movie without extension and basis for section video names

Type:

str

Some useful attributes are:

“write_to_movie” (bool=False)

Whether or not to write the animations into a video file.

“movie_file_extension” (str=”.mp4”)

The file-type extension of the outputted video.

“partial_movie_files”

List of all the partial-movie files.

Methods

add_audio_segment	This method adds an audio segment from an AudioSegment type object and suitable parameters.
add_partial_movie_file	Adds a new partial movie file path to scene.partial_movie_files and current section from a hash.
add_sound	This method adds an audio segment from a sound file.
begin_animation	Used internally by manim to stream the animation to FFMPEG for displaying or writing to a file.
clean_cache	Will clean the cache by removing the oldest partial_movie_files.
close_movie_pipe	Used internally by Manim to gracefully stop writing to FFMPEG's input buffer
combine_files
combine_to_movie	Used internally by Manim to combine the separate partial movie files that make up a Scene into a single video file for that Scene.
combine_to_section_videos	Concatenate partial movie files for each section.
create_audio_segment	Creates an empty, silent, Audio Segment.
end_animation	Internally used by Manim to stop streaming to FFMPEG gracefully.
finish	Finishes writing to the FFMPEG buffer or writing images to output directory.
finish_last_section	Delete current section if it is empty.
flush_cache_directory	Delete all the cached partial movie files
get_resolution_directory	Get the name of the resolution directory directly containing the video file.
init_audio	Preps the writer for adding audio to the movie.
init_output_directories	Initialise output directories.
is_already_cached	Will check if a file named with hash_invocation exists.
next_section	Create segmentation cut here.
open_movie_pipe	Used internally by Manim to initialise FFMPEG and begin writing to FFMPEG's input buffer.
output_image
output_image_from_array
print_file_ready_message	Prints the "File Ready" message to STDOUT.
save_final_image	The name is a misnomer.
write_frame	Used internally by Manim to write a frame to the FFMPEG input buffer.
write_opengl_frame
write_subcaption_file	Writes the subcaption file.

Attributes

force_output_as_scene_name

add_audio_segment(new_segment, time=None, gain_to_background=None)

This method adds an audio segment from an AudioSegment type object and suitable parameters.

Parameters:

• new_segment (AudioSegment) – The audio segment to add

• time (float | None) – the timestamp at which the sound should be added.

• gain_to_background (float | None) – The gain of the segment from the background.

add_partial_movie_file(hash_animation)

Adds a new partial movie file path to scene.partial_movie_files and current section from a hash. This method will compute the path from the hash. In addition to that it adds the new animation to the current section.

Parameters:

hash_animation (str) – Hash of the animation.

add_sound(sound_file, time=None, gain=None, **kwargs)

This method adds an audio segment from a sound file.

Parameters:

• sound_file (str) – The path to the sound file.

• time (float | None) – The timestamp at which the audio should be added.

• gain (float | None) – The gain of the given audio segment.

• **kwargs – This method uses add_audio_segment, so any keyword arguments used there can be referenced here.

begin_animation(allow_write=False, file_path=None)

Used internally by manim to stream the animation to FFMPEG for displaying or writing to a file.

Parameters:

allow_write (bool) – Whether or not to write to a video file.

clean_cache()

Will clean the cache by removing the oldest partial_movie_files.

close_movie_pipe()

Used internally by Manim to gracefully stop writing to FFMPEG’s input buffer

combine_to_movie()

Used internally by Manim to combine the separate partial movie files that make up a Scene into a single video file for that Scene.

combine_to_section_videos()

Concatenate partial movie files for each section.

Return type:

None

create_audio_segment()

Creates an empty, silent, Audio Segment.

end_animation(allow_write=False)

Internally used by Manim to stop streaming to FFMPEG gracefully.

Parameters:

allow_write (bool) – Whether or not to write to a video file.

finish()

Finishes writing to the FFMPEG buffer or writing images to output directory. Combines the partial movie files into the whole scene. If save_last_frame is True, saves the last frame in the default image directory.

finish_last_section()

Delete current section if it is empty.

Return type:

None

flush_cache_directory()

Delete all the cached partial movie files

get_resolution_directory()

Get the name of the resolution directory directly containing the video file.

This method gets the name of the directory that immediately contains the video file. This name is <height_in_pixels_of_video>p<frame_rate>. For example, if you are rendering an 854x480 px animation at 15fps, the name of the directory that immediately contains the video, file will be 480p15.

The file structure should look something like:

MEDIA_DIR
    |--Tex
    |--texts
    |--videos
    |--<name_of_file_containing_scene>
        |--<height_in_pixels_of_video>p<frame_rate>
            |--<scene_name>.mp4

Returns:

The name of the directory.

Return type:

str

init_audio()

Preps the writer for adding audio to the movie.

init_output_directories(scene_name)

Initialise output directories.

Notes

The directories are read from config, for example config['media_dir']. If the target directories don’t already exist, they will be created.

is_already_cached(hash_invocation)

Will check if a file named with hash_invocation exists.

Parameters:

hash_invocation (str) – The hash corresponding to an invocation to either scene.play or scene.wait.

Returns:

Whether the file exists.

Return type:

bool

next_section(name, type, skip_animations)

Create segmentation cut here.

Parameters:

• name (str) –

• type (str) –

• skip_animations (bool) –

Return type:

None

open_movie_pipe(file_path=None)

Used internally by Manim to initialise FFMPEG and begin writing to FFMPEG’s input buffer.

print_file_ready_message(file_path)

Prints the “File Ready” message to STDOUT.

save_final_image(image)

The name is a misnomer. This method saves the image passed to it as an in the default image directory.

Parameters:

image (ndarray) – The pixel array of the image to save.

write_frame(frame_or_renderer)

Used internally by Manim to write a frame to the FFMPEG input buffer.

Parameters:

frame_or_renderer (np.ndarray | OpenGLRenderer) – Pixel array of the frame.

write_subcaption_file()

Writes the subcaption file.