inSaiAI Intelligent Editing

Use when performing video/audio processing tasks including transcoding, filtering, streaming, metadata manipulation, or complex filtergraph operations with FFmpeg.

Security Scan

This is an instruction-only FFmpeg reference (shell-command output) that is internally consistent with its stated purpose and requests no credentials, installs, or extra privileges.

Purpose & Capability

Name/description match the content: the SKILL.md is a comprehensive FFmpeg guide (transcoding, filtering, metadata, filter_complex examples). Nothing in the file asks for unrelated resources or credentials.

Instruction Scope

Instructions are limited to FFmpeg/FFprobe command examples and explanations, referencing expected local files (input.mp4, watermark.png, filelist.txt, etc.). There are no steps that read unrelated system files, call external endpoints, or request secrets. Note: the skill's output-format is 'shell-command', so the agent will produce shell commands an executor might run — those commands should be reviewed before execution.

Install Mechanism

No install spec and no code files — lowest-risk form. The skill assumes ffmpeg/ffprobe are available on the host but does not attempt to fetch or install anything.

Credentials

The skill declares no required environment variables, credentials, or config paths. The content does not access or require secrets beyond typical local file inputs.

Persistence & Privilege

always is false and the skill is user-invocable; it does not request persistent or elevated platform privileges and does not modify other skills or system settings.

Assessment

This skill is a text-only FFmpeg how-to and appears coherent. Before installing or running commands produced by the agent: ensure ffmpeg/ffprobe are installed in a safe environment; always review the generated shell commands before executing them (they can overwrite files or run long CPU/GPU tasks); avoid running commands on sensitive systems or with privileged accounts; when processing untrusted media, run in an isolated sandbox or VM to limit potential risks. If you want the agent to execute commands automatically, require an explicit approval step to review each command first.

Comprehensive guide for professional video and audio manipulation using FFmpeg and FFprobe.

Core Concepts

FFmpeg is the leading multimedia framework, able to decode, encode, transcode, mux, demux, stream, filter and play almost anything that humans and machines have created. It is a command-line tool that processes streams through a complex pipeline of demuxers, decoders, filters, encoders, and muxers.

Common Operations

# Basic Transcoding (MP4 to MKV)
ffmpeg -i input.mp4 output.mkv

# Change Video Codec (to H.265/HEVC)
ffmpeg -i input.mp4 -c:v libx265 -crf 28 -c:a copy output.mp4

# Extract Audio (No Video)
ffmpeg -i input.mp4 -vn -c:a libmp3lame -q:a 2 output.mp3

# Resize/Scale Video
ffmpeg -i input.mp4 -vf "scale=1280:720" output.mp4

# Cut Video (Start at 10s, Duration 30s)
ffmpeg -i input.mp4 -ss 00:00:10 -t 00:00:30 -c copy output.mp4

# Fast Precise Cut (Re-encoding only the cut points is complex, so standard re-encoding is safer for precision)
ffmpeg -ss 00:00:10 -i input.mp4 -to 00:00:40 -c:v libx264 -crf 23 -c:a aac output.mp4

# Concatenate Files (using demuxer)
# Create filelist.txt: file 'part1.mp4' \n file 'part2.mp4'
ffmpeg -f concat -safe 0 -i filelist.txt -c copy output.mp4

# Speed Up/Slow Down Video (2x speed)
ffmpeg -i input.mp4 -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2.0[a]" -map "[v]" -map "[a]" output.mp4

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Processing Categories & When to Use

Codecs & Quality

Option	Use When
-c:v libx264	Standard H.264 encoding (best compatibility)
-c:v libx265	H.265/HEVC encoding (best compression/quality)
-crf [0-51]	Constant Rate Factor (lower is higher quality, 18-28 recommended)
-preset	Encoding speed vs compression (ultrafast, medium, veryslow)
-c:a copy	Pass-through audio without re-encoding (saves time/quality)

Filters & Manipulation

Filter	Use When
scale	Changing resolution (e.g., scale=1920:-1 for 1080p width)
crop	Removing edges (e.g., crop=w:h:x:y)
transpose	Rotating video (1=90deg CW, 2=90deg CCW)
fps	Changing frame rate (e.g., fps=30)
drawtext	Adding text overlays/watermarks
overlay	Picture-in-picture or adding image watermarks
fade	Adding fade-in/out effects (e.g., fade=in:0:30 for first 30 frames)
volume	Adjusting audio levels (e.g., volume=1.5 for 150% volume)
setpts	Changing video speed (e.g., setpts=0.5*PTS for double speed)
atempo	Changing audio speed without pitch shift (0.5 to 2.0)

Inspection & Metadata

Tool/Option	Use When
ffprobe -v error -show_format -show_streams	Getting detailed technical info of a file
-metadata title="Name"	Setting global metadata tags
-map	Selecting specific streams (e.g., -map 0:v:0 -map 0:a:1)

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Advanced: Complex Filtergraphs

Use filter_complex when you need to process multiple inputs or create non-linear filter chains.

# Example: Adding a watermark at the bottom right
ffmpeg -i input.mp4 -i watermark.png -filter_complex "overlay=main_w-overlay_w-10:main_h-overlay_h-10" output.mp4

# Example: Vertical Stack (2 videos)
ffmpeg -i top.mp4 -i bottom.mp4 -filter_complex "vstack=inputs=2" output.mp4

# Example: Side-by-Side (2 videos)
ffmpeg -i left.mp4 -i right.mp4 -filter_complex "hstack=inputs=2" output.mp4

# Example: Grid (4 videos 2x2)
ffmpeg -i v1.mp4 -i v2.mp4 -i v3.mp4 -i v4.mp4 -filter_complex "[0:v][1:v]hstack=inputs=2[top];[2:v][3:v]hstack=inputs=2[bottom];[top][bottom]vstack=inputs=2" output.mp4

# Example: Fade Transition (Simple crossfade between two clips)
# Requires manual offset calculation, using xfade is better
ffmpeg -i input1.mp4 -i input2.mp4 -filter_complex "xfade=transition=fade:duration=1:offset=9" output.mp4

Pro Editing Tips & Techniques

1. High-Quality GIF Creation

Standard conversion often results in poor colors. Use a palette for best results:

ffmpeg -i input.mp4 -vf "fps=15,scale=480:-1:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" output.gif

2. Audio Mixing (Background Music + Voice)

Mix background music at 30% volume with the main audio:

ffmpeg -i voice.mp4 -i bgm.mp3 -filter_complex "[1:a]volume=0.3[bg];[0:a][bg]amix=inputs=2:duration=first" -c:v copy output.mp4

3. Video Stabilization

Two-pass process to fix shaky footage:

# Pass 1: Analyze
ffmpeg -i shaky.mp4 -vf vidstabdetect -f null -
# Pass 2: Transform
ffmpeg -i shaky.mp4 -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 output.mp4

4. Color Correction & Enhancement

Adjust brightness, contrast, and saturation:

# brightness=0.05, contrast=1.1, saturation=1.2
ffmpeg -i input.mp4 -vf "eq=brightness=0.05:contrast=1.1:saturation=1.2" output.mp4

5. Automatic Thumbnail Sheet

Create a 3x3 grid of frames:

ffmpeg -i input.mp4 -vf "select='not(mod(n,100))',scale=320:-1,tile=3x3" -frames:v 1 preview.png

6. Remove Silence from Audio

Automatically cut silent parts from the beginning and end:

ffmpeg -i input.mp4 -af silenceremove=start_periods=1:start_silence=0.1:start_threshold=-50dB:stop_periods=1:stop_silence=0.1:stop_threshold=-50dB output.mp4

7. Hardsub Burning

Burn SRT/ASS subtitles directly into the video stream:

# Burn SRT
ffmpeg -i input.mp4 -vf "subtitles=subs.srt" output.mp4
# Burn ASS (supports advanced styling)
ffmpeg -i input.mp4 -vf "ass=subs.ass" output.mp4

8. Target File Size Compression

Calculate bitrate to fit a specific file size (e.g., 50MB for 60s video):

# Bitrate = (TargetSize_in_bits) / (Duration_in_seconds)
# 50MB = 400,000 bits. For 60s, bitrate ≈ 6600k
ffmpeg -i input.mp4 -b:v 6000k -maxrate 6000k -bufsize 12000k -c:a aac -b:a 128k output.mp4

9. Scene Change Detection

Extract frames where a scene change is detected (threshold 0.4):

ffmpeg -i input.mp4 -filter_complex "select='gt(scene,0.4)',metadata=print:file=scenes.txt" -vsync vfr scene_%03d.png

10. Extracting Frames at Specific Intervals

Extract one frame every 5 seconds:

ffmpeg -i input.mp4 -vf "fps=1/5" img_%03d.jpg

11. Batch Processing (Shell Snippet)

Convert all .mov files in a directory to .mp4:

for f in *.mov; do ffmpeg -i "$f" "${f%.mov}.mp4"; done

12. Live Streaming (RTMP)

Push a local file to a streaming server (YouTube/Twitch):

ffmpeg -re -i input.mp4 -c:v libx264 -preset veryfast -b:v 3000k -maxrate 3000k -bufsize 6000k -pix_fmt yuv420p -g 60 -c:a aac -b:a 128k -f flv rtmp://a.rtmp.youtube.com/live2/YOUR_STREAM_KEY

Hardware Acceleration

Platform	Codec	Command
NVIDIA (NVENC)	H.264	-c:v h264_nvenc
Intel (QSV)	H.264	-c:v h264_qsv
Apple (VideoToolbox)	H.265	-c:v hevc_videotoolbox

Constraints & Error Handling

• Stream Mapping: Always use -map for complex files to ensure you get the right audio/subtitle tracks.
• Seeking: Put -ss before -i for fast seeking (input seeking), or after -i for accurate seeking (output seeking).
• Format Support: Ensure the output container (extension) supports the codecs you've chosen.