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Avidemux is a simple tool for simple video processing tasks. The keyword here is simple: it does not offer tools like a timeline, multitrack editing, you cannot freely move or splice audio and video clips from various sources. However, Avidemux allows you to do elementary things in a very straightforward way.
When you open a video file using the Open button (Ctrl+O) on the main toolbar, there are 3 basic things you can do with it in Avidemux:
When you are done with cutting, setting encoders or filters, save the resulting video file using the Save button (Ctrl+S).
In addition, there are other small features you can use, like saving or replacing the audio track from the video, joining several video files or saving a snapshot of your video.
Avidemux works in two basic modes: copy mode and encoding mode.
When the audio or video encoder is set to Copy, it means no reencoding takes place, and the audio or video track from the input file is just copied to the resulting file as-is. This means it is very fast (usually a couple of minutes at most), and there is no quality loss.
Use the copy mode when:
When you select an audio or video encoder, the audio or video track is reencoded. If the compression is lossy (with most encoders it is), this implies quality loss. Encoding is also much slower than copying. Depending on the speed of your computer, it can take hours to complete.
Use the encoding mode when:
Since Avidemux is a tool that does not do things automagically for you and only executes the steps you directly tell it to perform, you should really understand what you are doing and why. Before you use Avidemux, you should understand basic characteristics of multimedia files, such as:
So, what does this all mean? Let's see a couple of use cases: