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above links.
Problem
You need to add text to videos—captions, watermarks, titles, or dynamic
labels. Manual video editing doesn’t scale for batch processing.
Solution
What’s in this recipe:
- Add simple text overlays
- Create styled captions with backgrounds
- Position text with alignment options
- Crop a rectangular region from a video
Use video.overlay_text() to burn text into videos with full control
over styling and position, and video.crop() to extract a rectangular
region.
Setup
%pip install -qU pixeltable
# Create a fresh directory
pxt.drop_dir('overlay_demo', force=True)
pxt.create_dir('overlay_demo')
Connected to Pixeltable database at: postgresql+psycopg://postgres:@/pixeltable?host=/Users/pjlb/.pixeltable/pgdata
Created directory ‘overlay_demo’.
<pixeltable.catalog.dir.Dir at 0x17e873990>
Load sample videos
# Create a video table
videos = pxt.create_table(
'overlay_demo/videos', {'video': pxt.Video, 'title': pxt.String}
)
# Insert a sample video
videos.insert(
[
{
'video': 's3://multimedia-commons/data/videos/mp4/ffe/ffb/ffeffbef41bbc269810b2a1a888de.mp4',
'title': 'Sample Video',
}
]
)
Created table ‘videos’.
Inserted 1 row with 0 errors in 3.21 s (0.31 rows/s)
1 row inserted.
Add a simple text overlay
# Add a simple watermark in the corner
videos.add_computed_column(
watermarked=videos.video.overlay_text(
'My Brand',
font_size=24,
color='white',
opacity=0.7,
horizontal_align='right',
horizontal_margin=20,
vertical_align='top',
vertical_margin=20,
)
)
Added 1 column value with 0 errors in 1.25 s (0.80 rows/s)
1 row updated.
Add YouTube-style captions
# Add a caption with a semi-transparent background box
videos.add_computed_column(
captioned=videos.video.overlay_text(
'This is a sample caption',
font_size=32,
color='white',
box=True, # Add background box
box_color='black',
box_opacity=0.8,
box_border=[6, 14], # Padding: [top/bottom, left/right]
horizontal_align='center',
vertical_align='bottom',
vertical_margin=70, # Distance from bottom
)
)
Added 1 column value with 0 errors in 1.08 s (0.92 rows/s)
1 row updated.
Add dynamic titles from table columns
# Add video title as an overlay (dynamic per video)
videos.add_computed_column(
titled=videos.video.overlay_text(
videos.title, # Use the title column!
font_size=48,
color='yellow',
opacity=1.0,
horizontal_align='center',
vertical_align='top',
vertical_margin=30,
)
)
Added 1 column value with 0 errors in 1.15 s (0.87 rows/s)
1 row updated.
# View all versions
videos.select(
videos.title,
videos.video,
videos.watermarked,
videos.captioned,
videos.titled,
).collect()
Crop a region from a video
Use video.crop() to extract a rectangular region from a video. This is
useful for focusing on a specific area of interest, removing borders, or
preparing clips for object-specific analysis.
# Crop using xywh format (default): [x, y, width, height]
videos.add_computed_column(cropped=videos.video.crop([100, 50, 320, 240]))
# Crop using xyxy format (common in object detection pipelines):
# videos.add_computed_column(
# cropped_xyxy=videos.video.crop([100, 50, 420, 290], bbox_format='xyxy')
# )
Added 1 column value with 0 errors in 0.56 s (1.78 rows/s)
1 row updated.
Explanation
Positioning options:
Styling options:
Background box options:
Requirements:
- FFmpeg must be installed and in PATH
See also
