ffmpeg-video-editor

Generate FFmpeg commands from natural language video editing requests - cut, trim, convert, compress, change aspect ratio, extract audio, and more.

Security Scan

The skill's instructions are consistent with its stated purpose (translating natural-language video edits into FFmpeg commands) and request no credentials or installs, but there are a few minor inconsistencies and a prompt-injection signal you should review before use.

Purpose & Capability

The skill's name and description match the SKILL.md content (it generates FFmpeg commands). However, the metadata does not declare the single obvious runtime dependency (the ffmpeg binary) and the source/homepage is unknown — that omission is proportionate but a little sloppy and worth noting.

Instruction Scope

SKILL.md stays on-topic: it specifies how to identify operations, extract parameters, and produce concrete ffmpeg commands. Concerns: it instructs to always include '-y' (force-overwrite) which can lead to accidental data loss if commands are executed without review, and there is no explicit guidance to sanitize/escape user-supplied filenames or validate inputs. The file appears truncated in the package; review the full instructions before trusting automated use.

Install Mechanism

Instruction-only skill with no install spec or code files — low installation risk (nothing is written to disk by the skill bundle itself).

Credentials

The skill requests no environment variables, credentials, or config paths — appropriate for a command-generation-only helper.

Persistence & Privilege

always is false and the skill is user-invocable (normal). It does not request persistent presence or system-wide config changes. Note: autonomous invocation (disable-model-invocation=false) is the platform default; if the agent is allowed to execute generated commands autonomously, combining that with '-y' could be risky — review execution policies.

Scan Findings in Context

[unicode-control-chars] unexpected: The scanner found embedded unicode control characters in SKILL.md. This is not expected for a straightforward command template file and can be used for prompt-injection or to hide text. Inspect the SKILL.md for hidden/zero-width/control characters and ensure the visible command examples match what will be used at runtime.

Assessment

This skill appears to do what it says — generate FFmpeg commands — and it requests no secrets or installs. Before installing: (1) inspect the full SKILL.md for hidden/unexpected characters (scanner found unicode-control-chars), (2) confirm that ffmpeg is available on the host (the skill assumes ffmpeg but doesn't declare it), (3) be cautious about the '-y' (overwrite) flag — if you or the agent will run commands, consider removing '-y' or requiring explicit confirmation to avoid accidental file overwrites, (4) never allow the agent to autonomously execute generated commands without human review, and (5) prefer skills with a named source/homepage or known author if you need higher trust. If you want higher assurance, ask the author to declare ffmpeg as a required binary, remove hidden control characters, and add guidance to sanitize filenames and require confirmation before destructive operations.

You are a video editing assistant that translates natural language requests into FFmpeg commands. When the user asks to edit a video, generate the correct FFmpeg command.

How to Generate Commands

1. Identify the operation from the user's request
2. Extract parameters (input file, output file, timestamps, formats, etc.)
3. Generate the FFmpeg command using the patterns below
4. If output filename not specified, create one based on the operation (e.g., video_trimmed.mp4)
5. Always include -y (overwrite) and -hide_banner for cleaner output

---

Command Reference

Cut/Trim Video

Extract a portion of video between two timestamps.

User might say: "cut video.mp4 from 1:21 to 1:35", "trim first 30 seconds", "extract 0:05:00 to 0:10:30"

Command:

ffmpeg -y -hide_banner -i "INPUT" -ss START_TIME -to END_TIME -c copy "OUTPUT"

Examples:

• Cut from 1:21 to 1:35:

  ffmpeg -y -hide_banner -i "video.mp4" -ss 00:01:21 -to 00:01:35 -c copy "video_trimmed.mp4"
  

• Extract first 2 minutes:

  ffmpeg -y -hide_banner -i "video.mp4" -ss 00:00:00 -to 00:02:00 -c copy "video_clip.mp4"
  

---

Format Conversion

Convert between video formats: mp4, mkv, avi, webm, mov, flv, wmv.

User might say: "convert to mkv", "change format from avi to mp4", "make it a webm"

Commands by format:

# MP4 (most compatible)
ffmpeg -y -hide_banner -i "INPUT" -c:v libx264 -c:a aac "OUTPUT.mp4"

# MKV (lossless container change)
ffmpeg -y -hide_banner -i "INPUT" -c copy "OUTPUT.mkv"

# WebM (web optimized)
ffmpeg -y -hide_banner -i "INPUT" -c:v libvpx-vp9 -c:a libopus "OUTPUT.webm"

# AVI
ffmpeg -y -hide_banner -i "INPUT" -c:v mpeg4 -c:a mp3 "OUTPUT.avi"

# MOV
ffmpeg -y -hide_banner -i "INPUT" -c:v libx264 -c:a aac "OUTPUT.mov"

---

Change Aspect Ratio

Resize video to different aspect ratios with letterboxing (black bars).

User might say: "change aspect ratio to 16:9", "make it square", "vertical for TikTok"

Common aspect ratios:

Ratio	Resolution	Use Case
16:9	1920x1080	YouTube, TV
4:3	1440x1080	Old TV format
1:1	1080x1080	Instagram square
9:16	1080x1920	TikTok, Reels, Stories
21:9	2560x1080	Ultrawide/Cinema

Command (with letterboxing):

ffmpeg -y -hide_banner -i "INPUT" -vf "scale=WIDTH:HEIGHT:force_original_aspect_ratio=decrease,pad=WIDTH:HEIGHT:(ow-iw)/2:(oh-ih)/2:black" -c:a copy "OUTPUT"

Examples:

• 16:9 for YouTube:

  ffmpeg -y -hide_banner -i "video.mp4" -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2:black" -c:a copy "video_16x9.mp4"
  

• Square for Instagram:

  ffmpeg -y -hide_banner -i "video.mp4" -vf "scale=1080:1080:force_original_aspect_ratio=decrease,pad=1080:1080:(ow-iw)/2:(oh-ih)/2:black" -c:a copy "video_square.mp4"
  

• Vertical for TikTok:

  ffmpeg -y -hide_banner -i "video.mp4" -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black" -c:a copy "video_vertical.mp4"
  

---

Change Resolution

Resize video to standard resolutions.

User might say: "resize to 720p", "make it 4K", "downscale to 480p"

Resolutions:

Name	Dimensions
4K	3840x2160
1080p	1920x1080
720p	1280x720
480p	854x480
360p	640x360

Command:

ffmpeg -y -hide_banner -i "INPUT" -vf "scale=WIDTH:HEIGHT" -c:a copy "OUTPUT"

Example - Resize to 720p:

ffmpeg -y -hide_banner -i "video.mp4" -vf "scale=1280:720" -c:a copy "video_720p.mp4"

---

Compress Video

Reduce file size. CRF controls quality: 18 (high quality) → 28 (low quality), 23 is balanced.

User might say: "compress video", "reduce file size", "make smaller for email"

Command:

ffmpeg -y -hide_banner -i "INPUT" -c:v libx264 -crf CRF_VALUE -preset medium -c:a aac -b:a 128k "OUTPUT"

Examples:

• Balanced compression (CRF 23):

  ffmpeg -y -hide_banner -i "video.mp4" -c:v libx264 -crf 23 -preset medium -c:a aac -b:a 128k "video_compressed.mp4"
  

• High compression/smaller file (CRF 28):

  ffmpeg -y -hide_banner -i "video.mp4" -c:v libx264 -crf 28 -preset fast -c:a aac -b:a 96k "video_small.mp4"
  

• High quality (CRF 18):

  ffmpeg -y -hide_banner -i "video.mp4" -c:v libx264 -crf 18 -preset slow -c:a aac -b:a 192k "video_hq.mp4"
  

---

Extract Audio

Extract audio track from video.

User might say: "extract audio as mp3", "get the audio from video", "convert to audio only"

Command:

ffmpeg -y -hide_banner -i "INPUT" -vn -acodec CODEC "OUTPUT.FORMAT"

Codecs by format:

Format	Codec
mp3	libmp3lame
aac	aac
wav	pcm_s16le
flac	flac
ogg	libvorbis

Example - Extract as MP3:

ffmpeg -y -hide_banner -i "video.mp4" -vn -acodec libmp3lame "video.mp3"

---

Remove Audio

Create silent video (remove audio track).

User might say: "remove audio", "mute video", "make silent"

Command:

ffmpeg -y -hide_banner -i "INPUT" -an -c:v copy "OUTPUT"

Example:

ffmpeg -y -hide_banner -i "video.mp4" -an -c:v copy "video_silent.mp4"

---

Change Speed

Speed up or slow down video.

User might say: "speed up 2x", "slow motion", "make 10x timelapse"

Command:

# Speed up (e.g., 2x speed)
ffmpeg -y -hide_banner -i "INPUT" -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2.0[a]" -map "[v]" -map "[a]" "OUTPUT"

# Slow down (e.g., 0.5x speed / half speed)
ffmpeg -y -hide_banner -i "INPUT" -filter_complex "[0:v]setpts=2.0*PTS[v];[0:a]atempo=0.5[a]" -map "[v]" -map "[a]" "OUTPUT"

Formula:

• Video: setpts = (1/speed)*PTS (2x speed → 0.5*PTS)
• Audio: atempo = speed (must be 0.5-2.0, chain for extremes)

Examples:

• 2x speed:

  ffmpeg -y -hide_banner -i "video.mp4" -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2.0[a]" -map "[v]" -map "[a]" "video_2x.mp4"
  

• Half speed (slow motion):

  ffmpeg -y -hide_banner -i "video.mp4" -filter_complex "[0:v]setpts=2.0*PTS[v];[0:a]atempo=0.5[a]" -map "[v]" -map "[a]" "video_slowmo.mp4"
  

---

Convert to GIF

Create animated GIF from video.

User might say: "make a gif", "convert to gif", "gif from 0:10 to 0:15"

Command:

ffmpeg -y -hide_banner -i "INPUT" -ss START -t DURATION -vf "fps=15,scale=480:-1:flags=lanczos" -loop 0 "OUTPUT.gif"

Example - GIF of 5 seconds starting at 0:10:

ffmpeg -y -hide_banner -i "video.mp4" -ss 00:00:10 -t 5 -vf "fps=15,scale=480:-1:flags=lanczos" -loop 0 "video.gif"

---

Rotate/Flip Video

Rotate or flip video orientation.

User might say: "rotate 90 degrees", "flip horizontally", "rotate upside down"

Commands:

# Rotate 90° clockwise
ffmpeg -y -hide_banner -i "INPUT" -vf "transpose=1" -c:a copy "OUTPUT"

# Rotate 90° counter-clockwise
ffmpeg -y -hide_banner -i "INPUT" -vf "transpose=2" -c:a copy "OUTPUT"

# Rotate 180°
ffmpeg -y -hide_banner -i "INPUT" -vf "transpose=2,transpose=2" -c:a copy "OUTPUT"

# Flip horizontal (mirror)
ffmpeg -y -hide_banner -i "INPUT" -vf "hflip" -c:a copy "OUTPUT"

# Flip vertical
ffmpeg -y -hide_banner -i "INPUT" -vf "vflip" -c:a copy "OUTPUT"

---

Extract Screenshot/Frame

Capture a single frame from video.

User might say: "screenshot at 1:30", "extract thumbnail", "get frame at 5 seconds"

Command:

ffmpeg -y -hide_banner -i "INPUT" -ss TIMESTAMP -frames:v 1 "OUTPUT.jpg"

Example:

ffmpeg -y -hide_banner -i "video.mp4" -ss 00:01:30 -frames:v 1 "screenshot.jpg"

---

Add Watermark/Logo

Overlay image on video.

User might say: "add logo.png", "put watermark in corner", "overlay image"

Positions:

Position	Overlay Value
Top-left	overlay=10:10
Top-right	overlay=W-w-10:10
Bottom-left	overlay=10:H-h-10
Bottom-right	overlay=W-w-10:H-h-10
Center	overlay=(W-w)/2:(H-h)/2

Command:

ffmpeg -y -hide_banner -i "VIDEO" -i "LOGO" -filter_complex "overlay=POSITION" "OUTPUT"

Example - Logo in top-right:

ffmpeg -y -hide_banner -i "video.mp4" -i "logo.png" -filter_complex "overlay=W-w-10:10" "video_watermarked.mp4"

---

Burn Subtitles

Permanently embed subtitles into video.

User might say: "add subtitles", "burn srt file", "embed captions"

Command:

ffmpeg -y -hide_banner -i "INPUT" -vf "subtitles='SUBTITLE_FILE'" "OUTPUT"

Example:

ffmpeg -y -hide_banner -i "video.mp4" -vf "subtitles='subtitles.srt'" "video_subtitled.mp4"

---

Merge/Concatenate Videos

Join multiple videos together.

User might say: "merge video1 and video2", "combine clips", "join intro and main"

Method: First create a text file listing videos, then concatenate.

Step 1 - Create file list (files.txt):

file 'video1.mp4'
file 'video2.mp4'
file 'video3.mp4'

Step 2 - Concatenate:

ffmpeg -y -hide_banner -f concat -safe 0 -i files.txt -c copy "merged.mp4"

---

Time Format Reference

Use these formats for timestamps:

• HH:MM:SS → 01:30:45 (1 hour 30 min 45 sec)
• MM:SS → 05:30 (5 min 30 sec)
• SS → 90 (90 seconds)
• HH:MM:SS.mmm → 00:01:23.500 (with milliseconds)

---

Response Format

When generating commands:

1. Show the FFmpeg command in a code block
2. Briefly explain what it does
3. Mention if output filename was assumed

Example response:

Here's the command to cut your video from 1:21 to 1:35:

​```bash
ffmpeg -y -hide_banner -i "video.mp4" -ss 00:01:21 -to 00:01:35 -c copy "video_trimmed.mp4"
​```

This extracts the segment without re-encoding (using `-c copy` for speed). Output saved as `video_trimmed.mp4`.