Editing and converting videos with Avidemux

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Among its strengths, Avidemux lets you compress single frames so that snippets are no longer bound to keyframes. Also, the program wins points with its numerous high-quality filters (Figure 2). Unlike many other programs, some decent documentation [3] about on settings is available.

Figure 2: Avidemux provides many clearly arranged, powerful filters that you can use to improve video quality.

The large selection of filters begins at deinterlacing. As always, video material often consists of two time-lagged transmitted half-images (even and odd numbered). These merge only on playback devices with the resolution and refresh rate determined for the video – practically never on a computer.

Deinterlacing, which even today can overwhelm computers with weaker CPUs, such as netbooks, during direct playback, mitigates the usually visible comb artifacts. High-quality deinterlacing, like that provided by the Yadif filter in Avidemux (Figure 3), is only available if you've already used it when editing or recompressing, instead of having the video player handle it.

Figure 3: Examples of Avidemux filters include (top down) removing comb effects from TV recordings (deinterlacing), color and brightness adjustments, black-and-white filtering, and video scaling using the Lanczos filter.

Avidemux also includes Resize/MPlayer resize , a powerful scaling filter. If you work with the computationally intensive Lanczos3 process, low-resolution videos become markedly sharper when upsizing the image on larger screens. Of course, the filter can't make up for any missing image details.

You can often use noise filters to improve the quality of analog TV recordings or videos recorded with noisy image sensors (Figure 4). The MPlayer denoise3d filter (or its improved variant, MPlayer hqdn3d , at the expense of performance) compares several successive frames, providing an almost 3D effect. The noise snow usually fluctuates faster than the rest of the video, therefore 3D filters can effectively eliminate it.

Figure 4: The filter dialogs are consistently clear and easy on the eye.

Blurring always destroys image details, but you can often rescue noisy videos with Gauss smoothing . Avidemux also provides a number of focusing filters that can mitigate the effects of poorly focused lenses. Among them are numerous algorithms for color, brightness, and contrast enhancement.

Filters work when Avidemux unpacks and re-compresses video and audio tracks, not when copying tracks.

Black and White

The Partial button limits the effects of a filter on only a part of the video. Unfortunately, you can't get soft transitions that way. To use multiple effects on the same snippet, be sure to note the start and end frame numbers.

Avidemux doesn't even claim to compete with track-based editors when it comes to targeted editing of regions. These editors let you add effects to certain sections by dragging and dropping. The extent of effects in Avidemux also pales in comparison to the correction filters it provides.

It does, however, provide a powerful filter preview that shows the results of effects in the Active Filter pane. The software also lets you shift the filters in the chain so you can see the effect of the chosen combination. A slider determines the position of the video preview.

Because the preview slider has no unit markings, finding a specific scene can be difficult. However, the software provides the option of displaying a second video window in the main window so that you can see the effects in the context with the original.

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