Simple Video Utils

Lightweight utilities for extracting frames and metadata from videos. Built for sign language processing workflows.

Goal

Provide simple, efficient tools for video processing in sign language research and applications. Uses PyAV for fast frame extraction with support for multiple formats (MP4, WebM) and remote URLs.

Installation

pip install simple-video-utils

Usage

Extract Video Metadata

from simple_video_utils.metadata import video_metadata

meta = video_metadata("video.mp4")
print(f"{meta.width}x{meta.height} @ {meta.fps} fps, {meta.duration}s")
# Output: VideoMetadata(width=1920, height=1080, fps=30.0, nb_frames=450, time_base='1/15360', duration=15.0)

Keyframe Indices (GOP Structure)

from simple_video_utils.metadata import keyframe_indices

keys = keyframe_indices("video.mp4")
# Presentation-order frame indices of the keyframes, e.g. [0, 250, 500]
# Demux-only (no decoding) — cheap even for long videos.

Read Frames from File

from simple_video_utils.frames import read_frames_exact

# Read specific frame range (inclusive)
frames = list(read_frames_exact("video.mp4", start_frame=0, end_frame=10))
# Returns 11 frames as numpy arrays (H, W, 3) in RGB format

# Read from frame to end of video
frames = list(read_frames_exact("video.mp4", start_frame=5, end_frame=None))

# Downsample to a target frame rate (drops frames uniformly, never duplicates)
frames = list(read_frames_exact("video.mp4", fps=15))

One Open, Many Reads

from simple_video_utils.metadata import open_video, video_metadata_from_container, keyframe_indices
from simple_video_utils.frames import read_frames_exact

# Metadata + windowed frame reads from a single container open —
# e.g. sampling indices from metadata, then decoding just that window.
with open_video("video.mp4") as video:
    meta = video_metadata_from_container(video)
    keys = keyframe_indices(video)
    frames = list(read_frames_exact(video, start_frame=10, end_frame=20))

Every helper rewinds the container before reading, so call order doesn't matter. Requires seekable input; consume one frame read at a time.

open_video sets the container's decode thread_type up front (default "AUTO") — PyAV forbids changing it once a stream's codec is open, which happens on first metadata probe or frame read. Pass thread_type="NONE" if you fork worker processes around decoding (e.g. a DataLoader): an inherited AUTO-threaded decoder can deadlock post-fork.

Read Frames from Stream

from simple_video_utils.frames import read_frames_from_stream

# Useful for uploaded files or in-memory video data
with open("video.mp4", "rb") as f:
    meta, frames_gen = read_frames_from_stream(f)
    for frame in frames_gen:
        # Process each frame (numpy array)
        pass

Slice into Clips

from simple_video_utils.slicing import slice_video

# One MP4 (bytes) per (start, end) second range
clips = slice_video("video.mp4", [(0.0, 1.5), (2.0, 3.2)])

# Center-crop to a square and resize to 256x256 (e.g. for model input)
clips = slice_video("video.mp4", [(0.0, 1.5)], size=256)

Split an incoming video stream into packet-copied clips as it arrives — each clip is yielded as soon as its window has been read, without re-encoding:

from simple_video_utils.slicing import slice_video_stream

with open("video.mp4", "rb") as stream:
    for clip in slice_video_stream(stream, duration=0.5):
        process(clip)

Join clips in order. Overlapping slices from the same encoded stream are de-duplicated and remuxed losslessly; anything else is decoded and encoded once as H.264 MP4:

from simple_video_utils.joining import join_videos

video = join_videos(clips)

Remote Videos

from simple_video_utils.metadata import video_metadata
from simple_video_utils.frames import read_frames_exact

# Works with remote URLs
url = "https://example.com/video.mp4"
meta = video_metadata(url)
frames = list(read_frames_exact(url, 0, 5))

Development

pip install -e ".[dev]"
pytest tests/
ruff check .