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Pull frames from video files at specified intervals for analysis, thumbnails, or training data.

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Problem

You have video files and need to extract frames for:
  • Object detection on video content
  • Creating thumbnails or previews
  • Building training datasets
  • Scene analysis and classification

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Solution

What’s in this recipe:
  • Extract frames at a fixed rate (FPS)
  • Extract a specific number of frames
  • Extract only keyframes for efficiency
You create a view with a FrameIterator that automatically extracts frames from each video. New videos are processed without extra code.

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Setup

%pip install -qU pixeltable

import pixeltable as pxt
from pixeltable.iterators import FrameIterator

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Load videos

# Create a fresh directory
pxt.drop_dir('video_demo', force=True)
pxt.create_dir('video_demo')

Connected to Pixeltable database at: postgresql+psycopg://postgres:@/pixeltable?host=/Users/pjlb/.pixeltable/pgdata
Created directory ‘video_demo’.
<pixeltable.catalog.dir.Dir at 0x1695d2650>
# Create table for videos
videos = pxt.create_table('video_demo.videos', {'video': pxt.Video})

Created table ‘videos’.
# Insert a sample video
videos.insert([
    {'video': 'https://raw.githubusercontent.com/pixeltable/pixeltable/main/docs/resources/bangkok.mp4'}
])

Inserting rows into `videos`: 1 rows [00:00, 212.90 rows/s]
Inserted 1 row with 0 errors.
1 row inserted, 2 values computed.

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Extract frames at fixed rate

Create a view that extracts 1 frame per second: 
# Extract 1 frame per second
frames = pxt.create_view(
    'video_demo.frames',
    videos,
    iterator=FrameIterator.create(
        video=videos.video,
        fps=1.0  # 1 frame per second
    )
)

Inserting rows into `frames`: 19 rows [00:00, 8687.65 rows/s]
# View extracted frames
frames.select(frames.frame, frames.pos).head(3)

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Extract keyframes only

For faster processing, extract only keyframes (I-frames): 
# Extract only keyframes (much faster for long videos)
keyframes = pxt.create_view(
    'video_demo.keyframes',
    videos,
    iterator=FrameIterator.create(
        video=videos.video,
        keyframes_only=True
    )
)
keyframes.select(keyframes.frame).head(3)

Inserting rows into `keyframes`: 7 rows [00:00, 3277.53 rows/s]

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Explanation

Extraction options:
Only one of fps, num_frames, or keyframes_only can be specified. When to use keyframes:
  • Quick video scanning and thumbnails
  • Initial content classification
  • Processing very long videos
Frame metadata: Each frame includes:
  • frame: The extracted image
  • pos: Frame position in the video
  • pts: Presentation timestamp

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See also