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Nanokit

Nanokit

Configuration

Input / Output

Trim / Cut

Extracts audio only. Adds the -vn flag.
Required for changing codecs, scaling, or burning subtitles.
Optimizes MP4 for web streaming (moves metadata to front).
Prints the command to the console instead of running it (Batch mode only).
Remux Mode: Lossless container change. Quality preserved.

Single Command

Mastering Media Workflows with FFmpeg

Build high-performance media pipelines directly in your browser. This tool generates secure, copy-pasteable commands for video compression, audio extraction, and language filtering without uploading your files.

Extracting Audio (Ripping)

To extract audio from a video file, use the 'Remove Video' toggle in the Video tab. This adds the `-vn` flag. Combine this with the Audio tab to convert the stream to MP3 or AAC. If you just need to extract the raw audio stream without conversion (e.g. mkv to ac3), select 'Copy Stream'.

Trimming and Cutting

Use the Trim Start and End inputs to cut a specific section of the file. Input format should be HH:MM:SS (e.g., 00:01:30). This generator places the seek flags `-ss` before the input file `-i`. This is known as 'fast seek' and is instantaneous, though slightly less frame-accurate than slow seeking.

Scaling and Resizing

If you need to reduce file size further, downscaling resolution (e.g., from 4K to 1080p) is highly effective. Enable 'Re-encode Video' to access the Resolution dropdown. This adds the `-vf scale=...` filter to the processing chain.

Why Re-encode?

Transcoding (Re-encoding) is necessary when you need to change the video codec (e.g., H.264 to H.265 for smaller file sizes) or burn in subtitles. However, it is CPU intensive and results in generation loss. If you just need to change the container (MKV to MP4), ensure 'Re-encode Video' is disabled to use Stream Copy mode, which is instantaneous and lossless.

Understanding CRF (Quality)

CRF (Constant Rate Factor) is the default quality setting for H.264/H.265. Unlike constant bitrate (CBR), CRF adjusts the bitrate dynamically to maintain a constant perceptual quality. Range is 0-51, where 0 is lossless, 23 is default, and 51 is worst quality. Lower CRF means higher bitrate and larger file size.