silence-cut

name

silence-cut

description

Use when the user wants to remove silent sections from a recording with real cuts (not just collapsed gaps), producing a tightened audio file. Wraps `auto-editor` for podcast/voice cleanup. Distinct from `truncate-silence` — that collapses internal silences via ffmpeg `silenceremove`; this performs threshold-driven edit decisions with margin/padding and crossfades, more aggressive at finding good cut points.

Silence Cut (auto-editor)

Tighten a recording by detecting and cutting silent sections with auto-editor. Optimised for spoken-word / podcast / voice memo cleanup where unfilled pauses, breath gaps, and dead air should be removed.

When to use

• The user has a long-form spoken recording with significant silent gaps.
• The user wants real cuts with crossfades, not in-place silence collapse.
• Used as a pre-step before EQ/loudnorm in a polish chain — saves processing time on later stages.

Do not use this skill when:

• The user wants the edit decisions (cut list / EDL) for review in a video editor → use silence-cut-edl.
• The user wants to merely shrink long pauses without changing structure → use truncate-silence.

Inputs

1. Input file — required. WAV / FLAC / MP3 / M4A all supported.
2. Threshold — silence detection level. Default: 4% (auto-editor's default). Lower = more aggressive cutting (catches quieter speech as silence). Common range: 2%–6%.
3. Margin — padding around kept audio so cuts don't clip word edges. Default: 0.2s on each side. Use 0.1s for tight edits, 0.4s for breathing room.
4. Output — defaults to <input-stem>.cut.<ext> next to the input. Caller can override.

Procedure

1. Verify auto-editor is on PATH (which auto-editor). If missing, point the user at install-deps (it's an optional dependency).

2. Build the command:

   auto-editor "<input>" \
     --edit "audio:threshold=<threshold>" \
     --margin <margin>sec \
     --output "<output>" \
     --no-open
   

   --no-open prevents auto-editor from launching a player on completion (it will otherwise on desktop systems).

3. Capture the auto-editor stdout. It reports the resulting duration and percentage cut — surface those numbers in the response.

4. Loudness sanity check (optional but recommended): run ffprobe -i <output> -hide_banner to confirm the file is valid and report duration delta.

Output

• Tightened audio file at the resolved output path.
• One-line summary: <input> (<orig-duration>) → <output> (<new-duration>, <pct>% cut).
• If the cut percentage is suspiciously high (>50%) or low (<5%), call it out and suggest threshold adjustment rather than silently accepting.

Notes

• auto-editor will re-encode to match the input format. For lossless preservation, prefer WAV input/output.
• For very long files (>2h), auto-editor uses meaningful memory — the user may want to chunk first.
• Default threshold is calibrated for clean recordings; for noisy environments raise the threshold or denoise first (/audio-production:denoise).