The Avidemux [1] video editor comes from a different era than today's dominant multitrack editing programs. The nonlinear approach is undoubtedly better for editing and creative effects. But, if you want to just cut the ends of videos, convert them to another format, or apply effects to the entire clip, multitrack editors are overkill. Simple tasks like that are easier to handle with the linear and single-track aspect of Avidemux (Figure 1).

Figure 1: The cutting functions and number of effects in the linear Avidemux editor are meager compared with those of nonlinear multitrack editors; yet, the program can handle many file formats and codecs and converts easily and quickly.

Avidemux also recognizes more video formats and codecs than most other specialized editors. If you're familiar with the old Windows program VirtualDub [2], you'll immediately feel at home with the Linux program that's been active since 2002 on SourceForge. Picking up Avidemux for the first time is easier than learning the much more complex applications with a nonlinear design.

Steering Wheel

Navigating through a video is done via a simple slider in the lower third of the window instead of with a timeline with units. However, the program shows the current position with an additional time field in the format hours:minutes:seconds:hundredths of seconds . Manually entering a value in this field moves you to the appropriate spot.

To the right of the slider, the program provides a jog wheel (Figure  1)  – similar to the device on many professional editing tables and video recorders. With it, you can fast-forward or rewind at various speeds depending on how far you press the jog wheel by moving the mouse to the right or left. This tool helps you find scenes in longer videos.

To navigate one frame at a time, you can click the left or right arrow, and to go one keyframe at a time, click the up or down arrow – provided the time slider has focus in the Avidemux window. Pressing the spacebar starts and stops playback.

Under the time slider are some more buttons that search for the next dark frame, often found at the beginning and end of commercial breaks. Pos 1 and End jump to the beginning and end, respectively, of the loaded clip.

Patchwork

Using the A and B buttons at the bottom right, you can set beginning and end markers for what should be a contiguous block. If a selection is active during a save, the software crops the video accordingly. You can cut out selected frames with Ctrl+X and add them to another location with Ctrl+V.

However, because the editor doesn't provide an undo operation, it's recommended that you first export all the cut sections, made easy with the convenient fast-forward and rewind functions. In the second step, add the snippet to a clip by choosing File | Add or by pressing Ctrl+H.

Note that Avidemux should not be your first choice for video editing – for one thing, it combines snippets only of the same resolution and frame rate. However, this limitation shouldn't be a problem if the data comes from the same source.

Exporting cuts usually takes just seconds – and just minutes for longer clips, provided Copy mode is active for video and audio (on the left in Figure 1). In this case, the software copies the video and audio streams from the file instead of compressing them again, which spares some of the usual computation.

If you want to compress the sections or add effects, compression, which occurs without user intervention, is the correct action to take. A job list (File | Add to Job List and File | View Job List ) even processes several projects all in one go.

Freshly Brewed

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.

Repackaged

Among Avidemux's specialties are its recompressing and conversion into other file formats. The program reads and writes the popular formats AVI, MPEG, OGM, and MKV (Matroska), as well as Flash and Windows ASF videos. It generates PS files for DVDs and TS streaming files and MP4 files for mobile devices, and it reads analog Nuppelvideo format files from the MythTV video recorder software and numbered sequences of single-image frames.

Avidemux also supports all codecs from FFmpeg (MPEG-1/2, HuffYUV, FFV1, LavC MPEG4). Unfortunately, it doesn't use the pre-installed FFmpeg version, so neither license-determined editing nor updates can be applied. It also integrates the external libraries x264 and Xvid, which provide full functionality. Audio codecs provided include Vorbis, FAAC, MP2, AC3, MP3, and uncompressed Wave audio.

Video files tend to be so large that the benefit of compressing plays a role even with the current capacity of hard drives. Thus, DVDs still coded with the MPEG-2 process dating from the 1990s get reduced to half their original size with roughly the same picture quality after recompressing with H264. The matching dialog is hidden in Avidemux under the video track option MPEG-4 AVC . You can select this option instead of the usual Copy option active at startup. Clicking Configure under the codec selections opens the settings with quite a daunting set of tabs at first glance.

Fortunately, the General tab encompasses the few really important settings. All the others require some expertise in compression algorithms. You can save the settings in a profile that the software displays at the top of the dialog.

Double-Stitched

At first, you need to decide on an Encoding Mode . Two methods are available for adjusting the balance between quality and file size (Figure 5). The first method works with the bit rate per second. The size of the compressed file is determined simply by the bit rate times the duration. However, the audio track is missing from this calculation. Moreover, the bit rate is only an approximation; the codec can overrate or underrate it on the basis of the level of detail or noise in the material.

Figure 5: Avidemux is ideal for compressing DVD video material with the H264 codec, which saves about 50 percent of the space normally used with comparable optics.

Alternatively, you can control the quality when compressing using so-called quantization, an abstract measure of compression strength. It relates less to size than to the constancy of the optical quality. Factors of 25 are the norm for today's standards.

A value of less than 20 causes the file size to increase dramatically, but you won't get a result with a better quality. Factors more than 30 usually result in block artifacts. With factors more than 40, the quality degrades to the point that you can't distinguish between human beings.

Apart from bitrate and quanticized compression, the coding mode also differs after the number of passes. Processes with two passes take almost twice as long but provide a significantly better ratio of file size to quality. For two passes, the H.264 codec offers the choice of bitrate-based compression or direct input of the desired file size.

However, this has no effect on the audio track and is, therefore, not included in the calculation. Some help comes from the calculator in the Tools menu (or press F7) that calculates the size of the audio track and subtracts it from the desired file size.

Compact Package

Avidemux is available in functionally identical Qt and Gtk versions. Distributions generally provide packages for both front ends. Many functions are also available from the command line [4], almost all over a JavaScript interface [5].

The first stable version of Avidemux appeared May 9, 2013, as version 2.6.4 in the 2.6 series. A special advantage to the program is that the script delivered with the source code automatically compiles the software and packages it in an RPM or Debian package [6]. Version 2.6 is based on a newly written core, but preserves the well-known interface with few changes (Figure 6).

Figure 6: The interface of the finally stable series 2.6 of Avidemux has changed little, even though it is based on a new core that works more reliably in synchronizing audio and video.

The program's author promises that the new major version fixes frequently encountered audio and video synchronization problems of the past. The interface, however, has changed little. The packages are now called avidemux3_qt4 , avidemux3_gkt , and avidemux3_cli , instead of the previous avidemux2 plus a suffix. This scheme allows the 2.5 and 2.6 versions to be installed in parallel.

Conclusion

Avidemux plays in a different league from the nonlinear multitrack editors. Its strengths lie in format conversion and compression, which can save you burdensome intermediary steps. It is also quite good for simple editing. The software provides many effects for retouching that are, unfortunately, often difficult to work with.

Despite its mature age, Avidemux does crash from time to time – yet usually less than its competitors , which are not always stable.