jump-cut-pacing
تدوین سریع و طبیعی ویدئوهای گفت‌وگومحور با حذف مکث‌های اضافی و جامپ‌کات امن برای چهره
این مهارت ویدئوهای talking-head و مصاحبه را با شناسایی سکوت‌ها، حفظ مکث‌های طبیعی و حذف شروع‌های ناموفق یا هوای مرده کوتاه‌تر می‌کند. برش‌ها در مرز جمله‌ها قرار می‌گیرند تا ریتم سریع‌تر شود، بدون اینکه گفتار مصنوعی یا نفس‌گیر به نظر برسد.
برای هر بخش، برنامه‌ی برش، میزان punch-in و نقطه‌ی برش عمودی امن برای چهره تعیین می‌شود و سپس با FFmpeg رندر می‌گیرد. خروجی از نظر پیوستگی صدا، قاب‌بندی صورت، حرکات دست و تکراری‌نشدن الگوی زوم بررسی می‌شود.
چه چیزی می‌گیرید
- تحلیل سکوت‌ها و ساخت cut plan شامل بازه‌های گفتار و padding تنفس
- حذف هدفمند dead air، تپق‌ها و شروع‌های رهاشده به‌جای پاک‌کردن همه‌ی مکث‌ها
- جامپ‌کات و punch-inهای متناوب با حفظ پیشانی، چشم‌ها و چانه در قاب
- رندر بخش‌ها و اتصال ویدئو و صدای اصلی با FFmpeg
- کنترل کیفیت ریتم، پیوستگی صدا و طبیعی‌بودن اجرای نهایی
برای چه کاری خوب است
- ویدئوهای آموزشی، پادکست تصویری و talking-head با یک گوینده
- مصاحبه‌هایی که مکث‌های طولانی، تپق یا شروع‌های دوباره دارند
- پروژه‌هایی که به ریتم فشرده‌تر و جامپ‌کات‌های ظریف نیاز دارند
برای چه کاری نیست
- اجراهایی که مکث در آن‌ها بخشی از درام، کمدی یا تأکید معنایی است
- ویدئوهایی که ریتمشان به حرکت پیوسته‌ی دوربین یا همگام‌سازی با موسیقی وابسته است
- فوتیج چنددوربینه‌ای که تغییر قاب طبیعی، مشکل تدوین را از قبل حل کرده است
دربارهٔ این اسکیل
Jump Cut and Pacing
Treat pacing as editorial direction, not automatic silence deletion.
The goal is to remove dead air while preserving breath, thought, emphasis, and the speaker's physical continuity. A fast cut is not automatically a better cut.
Decision gate
Use this skill when the source is mainly a presenter or interview and the editing problem is cadence.
Do not use it as the main solution when:
- pauses are intentional dramatic beats
- the source depends on performance timing, comedy, or music sync
- a cut would remove a breath needed for intelligibility
- the reference uses continuous camera movement rather than editorial punch-ins
- the speaker already changes framing naturally between cameras
When uncertain, preserve the pause and flag it for review.
Editorial rules before automation
- Keep micro-pauses that make speech human.
- Cut retakes, abandoned starts, and dead air more aggressively than sentence breathing.
- Place cuts at phrase boundaries when possible.
- Avoid two hard cuts inside one short clause.
- Use a punch-in to clarify a cut, not on every sentence by habit.
- If the speaker moves strongly across a cut, prefer a wider frame or b-roll bridge instead of a tighter crop.
Read references/pacing-rules.md before changing the default thresholds.
Workflow
Step 1: Build the cut plan
Use the bundled planner:
~~~bash
python3 scripts/cut_plan.py "$WORK/src.mov" --min-silence 0.45 -o "$WORK/cut_plan.json"
~~~
The planner probes the source duration with ffprobe when total duration is omitted. FFmpeg or ffprobe failure is a hard failure and must not produce a successful empty plan.
The plan contains:
- source start and end for every kept speech segment
- preserved lead padding before speech
- preserved tail padding after speech
- alternating zoom values
- zoom_anchor_y for face-safe vertical framing
Step 2: Review the plan as an editor
Before rendering, inspect:
- whether a meaningful pause was classified as dead air
- whether any kept segment is too short to read naturally
- whether two cuts happen too close together
- whether zoom alternation matches emphasis rather than becoming a metronome
If a section feels rushed, restore time. Do not lower the silence threshold globally just to fix one sentence.
Step 3: Render each segment with its planned framing
A cut plan is not complete until the zoom fields affect the pixels.
For every segment with source interval S to E, zoom Z, and anchor A, build a video branch using this pattern:
~~~text
[0:v]
trim=start=S:end=E,
setpts=PTS-STARTPTS,
scale=iw*Z:ih*Z,
crop=iw/Z:ih/Z:(iw-ow)/2:(ih-oh)*A
[vN]
[0:a]
atrim=start=S:end=E,
asetpts=PTS-STARTPTS
[aN]
~~~
Then concatenate the matching video and audio branches in plan order:
~~~text
[v0][a0][v1][a1]...[vN][aN]concat=n=SEGMENT_COUNT:v=1:a=1[outv][outa]
~~~
For Z equal to 1.0, this resolves to the original framing. For a punch-in, the scaled frame is cropped back to delivery size with the vertical crop controlled by zoom_anchor_y.
If the active project already uses HyperFrames or another deterministic timeline, translate the same segment plan into that runtime instead of building a second renderer.
Step 4: Protect the face
Verify at least:
- crown and hair are not clipped
- eyes stay comfortably above center
- chin is not trapped against captions
- hand gestures are not removed by a punch-in
- the crop still works if the presenter leans during the segment
Step 5: Protect audio continuity
Use the camera or production master audio. Do not reintroduce transcription audio into the final edit.
Check the assembled output for:
- clipped consonants
- missing word tails
- clicks at cuts
- sudden room-tone changes
- accidental loudness pumping
Rhythm patterns
A useful sequence can be:
wide -> punch -> wide -> hold -> punch
A weak sequence is:
wide -> punch -> wide -> punch -> wide -> punch
The second pattern exposes the automation. Break the pattern when the meaning changes.
Creative QA
Hard-fail the edit if:
- the speaker sounds unnaturally breathless
- zooms happen with no semantic reason
- face framing becomes less stable after the edit
- the same two zoom states repeat for the whole video
- a cut lands inside a meaningful word or gesture
- the output is shorter but less comprehensible
What I learned the hard way
- Centered crops often clip foreheads in vertical talking-head footage.
- Removing every pause makes natural speech feel synthetic.
- Alternating zoom is useful camouflage, but visible repetition becomes its own defect.
- The rendered video is the evidence. A correct JSON plan is not proof that pacing works.