Avidemux

Avidemux is a free, open source video editor built for straightforward cutting, filtering, and encoding tasks. Its strongest feature is frame-accurate cutting in Copy mode, which trims video without re-encoding. The result is near-instant processing with zero quality loss. It handles AVI, MP4, MKV, and FLV files, and runs on Windows, macOS, and Linux.

What it does

The basic workflow is simple: open a video file, set point A (start of the section you want to keep or remove) and point B (end), then either delete the selection or save. With Video Output and Audio Output both set to Copy, Avidemux writes the result directly without touching the encoded data. A two-hour video can be trimmed in seconds this way.

When you do need to re-encode, Avidemux supports common codecs including H.264, H.265, and MPEG-4 on the video side, plus AAC, MP3, and AC3 for audio. The filter pipeline (Video menu > Filters) offers practical tools: crop to remove black bars, resize to change resolution, denoise to reduce grain, and subtitle burn-in to permanently embed SRT or ASS subtitle files into the video. Filters stack in sequence and you can preview the result before processing.

For container changes without quality loss, set both outputs to Copy and just change the Output Format from, say, AVI to MP4. This remuxes the streams into the new container instantly. You can also append files (File > Append) to join multiple clips, as long as they share the same codec and resolution.

Who it is for

I recommend Avidemux when you have a specific, contained task: cut a segment from a video, convert a file to a different format, crop black bars, or burn in subtitles. It is not a replacement for timeline editors like DaVinci Resolve or Kdenlive. But for the jobs it handles, it does them faster and with less overhead than any full editing suite.