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.

Parameters:

• renderer (CairoRenderer | OpenGLRenderer)

• scene_name (str)

• kwargs (Any)

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_partial_movie_stream	Close the currently opened video container.
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.
encode_and_write_frame	For internal use only: takes a given frame in np.ndarray format and writes it to the stream
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.
listen_and_write	For internal use only: blocks until new frame is available on the queue.
next_section	Create segmentation cut here.
open_partial_movie_stream	Open a container holding a video stream.
output_image
print_file_ready_message	Prints the "File Ready" message to STDOUT.
save_image	This method saves the image passed to it in the default image directory.
write_frame	Used internally by Manim to write a frame to the FFMPEG input buffer.
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.

Return type:

None

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 | None) – Hash of the animation.

Return type:

None

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

This method adds an audio segment from a sound file.

Parameters:

• sound_file (StrPath) – 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 (Any) – This method uses add_audio_segment, so any keyword arguments used there can be referenced here.

Return type:

None

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.

• file_path (TypeAliasForwardRef('~manim.typing.StrPath') | None)

Return type:

None

clean_cache()

Will clean the cache by removing the oldest partial_movie_files.

Return type:

None

close_partial_movie_stream()

Close the currently opened video container.

Used internally by Manim to first flush the remaining packages in the video stream holding a partial file, and then close the corresponding container.

Return type:

None

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.

Return type:

None

combine_to_section_videos()

Concatenate partial movie files for each section.

Return type:

None

create_audio_segment()

Creates an empty, silent, Audio Segment.

Return type:

None

encode_and_write_frame(frame, num_frames)

For internal use only: takes a given frame in np.ndarray format and writes it to the stream

Parameters:

• frame (PixelArray)

• num_frames (int)

Return type:

None

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.

Return type:

None

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.

Return type:

None

finish_last_section()

Delete current section if it is empty.

Return type:

None

flush_cache_directory()

Delete all the cached partial movie files

Return type:

None

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>
                |--partial_movie_files
                |--<scene_name>.mp4
                |--<scene_name>.srt

Returns:

The name of the directory.

Return type:

str

init_audio()

Preps the writer for adding audio to the movie.

Return type:

None

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.

Parameters:

scene_name (str)

Return type:

None

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

listen_and_write()

For internal use only: blocks until new frame is available on the queue.

Return type:

None

next_section(name, type_, skip_animations)

Create segmentation cut here.

Parameters:

• name (str)

• type_ (str)

• skip_animations (bool)

Return type:

None

open_partial_movie_stream(file_path=None)

Open a container holding a video stream.

This is used internally by Manim initialize the container holding the video stream of a partial movie file.

Parameters:

file_path (TypeAliasForwardRef('~manim.typing.StrPath') | None)

Return type:

None

print_file_ready_message(file_path)

Prints the “File Ready” message to STDOUT.

Parameters:

file_path (StrPath)

Return type:

None

save_image(image)

This method saves the image passed to it in the default image directory.

Parameters:

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

Return type:

None

write_frame(frame_or_renderer, num_frames=1)

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

Parameters:

• frame_or_renderer (PixelArray | OpenGLRenderer) – Pixel array of the frame.

• num_frames (int) – The number of times to write frame.

Return type:

None

write_subcaption_file()

Writes the subcaption file.

Return type:

None