movis.layer

The layer module defines base protocols for representing various kind of video layers in Layer and BasicLayer. The remaining classes in this module represent its implementations.

Composition

movis.layer.composition.Composition	A base layer that integrates multiple layers into one video.
movis.layer.composition.LayerItem	A wrapper layer for managing additional info.

Image, Video, Audio, etc.

movis.layer.media.Image	Still image layer to encapsulate various formats of image data and offer time-based keying.
movis.layer.media.ImageSequence	Image sequence layer to encapsulate various formats of images.
movis.layer.media.Video	Video layer to encapsulate various formats of video data.
movis.layer.media.Audio	Audio layer to encapsulate various formats of audio data.
movis.layer.media.AudioSequence	Audio sequence layer to handle multiple audio files.

Drawing layers

movis.layer.drawing.Line	Draw a line from start to end.
movis.layer.drawing.Rectangle	Draw a rectangle with rounded corners.
movis.layer.drawing.Ellipse	Draw an ellipse.
movis.layer.drawing.Text	Draw a text.
movis.layer.drawing.FillProperty	A property for filling a shape.
movis.layer.drawing.StrokeProperty	A property for stroking a shape.

Texture layers

movis.layer.texture.Gradient	A layer that generates a gradient image.
movis.layer.texture.Stripe	A layer that generates a stripe pattern.

Layer-to-Layer Composition

movis.layer.layer_ops.AlphaMatte	A layer that applies alpha matte to the target layer using the mask layer.
movis.layer.layer_ops.LuminanceMatte	A layer that replaces the alpha channel of the target layer with the luminance of the mask layer.

Protocol

class movis.layer.protocol.Layer(*args, **kwargs)

The protocol that defimes the minimal interface for a layer.

__call__(time: float) → ndarray | None

The minimum required method to implement a layer. All layers must implement it.

Specifically, this method returns a numpy.ndarray of shape (H, W, 4) with RGBA order and dtype as numpy.uint8, or None, given a time. When a numpy.ndarray is returned, Movis considers this array as an image and uses it as one of the layers for rendering the video. If None is returned, Movis does not render its layer.

Args:

time: A scalar variable representing time.

Returns:

None if nothing is to be rendered, otherwise numpy.ndarray.

class movis.layer.protocol.BasicLayer(*args, **kwargs)

The protocol that defines the basic interface for a layer with some optional properties.

__call__(time: float) → ndarray | None

The minimum required method to implement a layer. All layers must implement it.

Specifically, this method returns a numpy.ndarray of shape (H, W, 4) with RGBA order and dtype as numpy.uint8, or None, given a time. When a numpy.ndarray is returned, Movis considers this array as an image and uses it as one of the layers for rendering the video. If None is returned, Movis does not render its layer.

Args:

time: A scalar variable representing time.

Returns:

None if nothing is to be rendered, otherwise numpy.ndarray.

property duration: float

An optional but desirable property for any layer implementation.

This property should return the duration for which the layer will persist. If not implemented, it is assumed that the layer has an indefinitely large duration.

Returns:

The duration for which the layer will persist.

get_key(time: float) → Hashable

An optional but desirable method for any layer implementation.

This method returns a hashable value representing the ‘state’ of the layer at a given time. If the keys are the same, the array returned by this layer must also be identical. It is used for caching compositions, and in the case of videos where static frames persist, Movis will use the cache to accelerate video rendering.

If not implemented, Movis assumes that the layer is independent at each time frame, i.e., it will not use cache-based rendering.

Returns:

A hashable key that represents the state of the layer at the given time.

class movis.layer.protocol.AudioLayer(*args, **kwargs)

__call__(time: float) → ndarray | None

The minimum required method to implement a layer. All layers must implement it.

Specifically, this method returns a numpy.ndarray of shape (H, W, 4) with RGBA order and dtype as numpy.uint8, or None, given a time. When a numpy.ndarray is returned, Movis considers this array as an image and uses it as one of the layers for rendering the video. If None is returned, Movis does not render its layer.

Args:

time: A scalar variable representing time.

Returns:

None if nothing is to be rendered, otherwise numpy.ndarray.

get_audio(start_time: float, end_time: float) → ndarray | None

An optional method for implementing an audio layer.

This method returns an audio clip of the layer between the given start and end times. The returned audio clip should be a two-dimensional numpy.ndarray with a shape of (2,T), where T is the number of samples in the audio clip and 2 is the number of channels. The sample rate of the audio clip should be AUDIO_SAMPLING_RATE (= 44100).

If not implemented, Movis assumes that the layer does not have any audio.

Args:

start_time: The start time of the audio clip. end_time: The end time of the audio clip.

Returns:

A two-dimensional numpy.ndarray with a shape of (2,T) and sample_rate is an integer representing the sample rate of the audio clip.