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77 lines
2.7 KiB
Markdown
77 lines
2.7 KiB
Markdown
# speed
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## Description
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Changes the playback speed of the input video and audio simultaneously.
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This module is useful for slow motion, fast motion, timelapse, rhythmic edits, and any effect requiring temporal compression or expansion.
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## Purpose
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`speed` is designed for creators who want to:
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- increase or decrease playback speed uniformly,
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- generate slow-motion or fast-motion stylization,
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- build rhythmic visual edits synced to music,
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- create timelapse effects without external tools,
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- maintain audio pitch relationship unless later reprocessed.
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## How It Works
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1. **Timebase Adjustment**
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Video frames are retimed according to the provided speed factor.
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2. **Audio Resampling**
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Audio is also sped up or slowed down to match the new video duration.
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3. **Encoding**
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The resulting retimed clip is encoded using global Videobeaux settings (codec, CRF, pixel format).
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### Notes
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- Speed values **greater than 1.0** = faster playback.
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- Speed values **less than 1.0** = slower playback.
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## Program Template
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```bash
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videobeaux -P speed \
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-i input.mp4 \
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-o output.mp4 \
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--speed_factor VALUE
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```
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## Arguments
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- **speed_factor** — Multiplier for playback speed.
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- `0.5` → half-speed (slow motion)
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- `2.0` → double-speed (fast motion)
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- `0.25` → quarter-speed
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- `4.0` → 4× speed
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## Real World Example
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```bash
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videobeaux -P speed \
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-i myvideo.mp4 \
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-o speed_styled.mp4 \
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--speed_factor EXAMPLE
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```
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## Program Output
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<video controls preload="metadata" style="max-width:100%; border-radius:8px; margin:1em 0;">
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<source src="https://github.com/schwwaaa/videobeaux/assets/7625379/c27efdb1-ae81-4d8d-a153-de6294b7fedf" type="video/mp4">
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Your browser does not support the video tag.
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</video>
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## Technical Notes
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- Audio pitch will shift unless processed later with an external pitch-correction tool.
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- High speed factors may expose motion judder depending on frame rate.
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- Very slow speeds may require additional interpolation if smooth motion is desired (use `frame_interpolate` first).
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- Retime operations do not introduce new frames; they only alter timing unless combined with interpolation.
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## Recommended Usage
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- Music video edits synced to rhythmic patterns.
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- Timelapse creation.
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- Slow-motion mood sequences.
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- Fast-motion montage, humor, or surreal pacing.
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- Preprocessing before LUTs or effects when timing matters.
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## Quality Tips
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- For the cleanest slow motion, run `frame_interpolate` before `speed` to create missing frames.
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- Use lower CRF for crisp motion edges when speeding up footage.
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- Use higher CRF for intentionally grittier motion artifacts.
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- Pair with `looper_pro` for smooth motion loops.
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- Combine with `nostalgic_stutter` or `bad_animation` for stylized cadence distortion.
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