This page contains details and explainations for the options in the Preferences dialog. These will help you configure and customize Avidemux more to your liking when you are using it.

Some changes require a restart to be taken into account, especially the audio and video decoding/displaying options.

• Message level(nbsp)(ndash) set the desired level of message popups within Avidemux. Regardless of this setting you will still be prompted to necessarily decisions or questions:
  • No alerts(nbsp)(ndash) will not pop up any message about success or failures.
  • Display only error alerts(nbsp)(ndash) only allow pop up with problems or failure messages.
  • Display all alerts(nbsp)(ndash) allow all messages to pop up with all information.
• Swap marks A and B if A > B(nbsp)(ndash) switch the A and B marks if a new A mark is greater than the old B mark.
• Go to systray when encoding(nbsp)(ndash) Avidemux will minimize itself when an encoding is running and restores when it is done.

• Automatically index MPEG files(nbsp)(ndash) automatically start indexing MPEG files immediately with asking if it should index them. It will still ask about appending multiple mpeg type files though.
• Disable NuppelVideo resync(nbsp)(ndash) by default, Avidemux will try to synchronize audio and video on nuv file (only if audio is PCM!). If this option is activated, no sync attempt will be made.
• Use libavcodec MPEG decoder(nbsp)(ndash) enabling this option will use libavcodec instead of mpeg2dec to decode MPEG-1/MPEG-2 video. It is mainly for CPU architectures that have no HW acceleration for mpeg2dec. libavcodec MPEG-2 decoder is more robust toward slightly erroneous streams and has good error concealment code to hide errors (from DVB recordings for example).
• Set Default Postprocessing Level(nbsp)(ndash) set defaults for a few post encoding filters to apply to video before saving file.

• MPEG auto split (MB)(nbsp)(ndash) set the size at which to split MPEG videos when saving large files.
• Use OpenDML (don't split large AVI files)(nbsp)(ndash) when the output format is set to AVI, save the file in the OpenDML format instead of the old AVI format (which has a file size limit). This enables you to save files over 4(nbsp)GB without splitting them.

Audio output:

• Dummy: Actually means no audio device, so no audio playback.
• Win32: Use Windows audio system (Windows only).
• CoreAudio: Use CoreAudio audio system (Mac(nbsp)OS(nbsp)X only).
• OSS: Open Sound System. Modern Linux systems use ALSA by default, but OSS is still used on other UNIX-like systems.
• ARTS: Analog Real time synthesizer (aRts). An application that simulates an analog synthesizer under KDE/Linux. One key component of aRts is the soundserver which mixes several soundstreams in realtime. The soundserver called aRtsd (d for Daemon) is also utilized as the standard soundserver for KDE. Obviously recommended for use in KDE.
• ALSA: Advanced Linux Sound Architecture. The newer Linux sound system (kernel module). It handles multiple audio applications and stream mixing. Generally recommended (though aRts is better for KDE(nbsp)3, and ESD is better for GNOME).
  • The default ALSA device is plughw:0,0. If this does not work, try hw:0.
• ESD: Enlightened Sound Daemon (ESD or EsounD). The sound server for Enlightenment and GNOME. It mixes several sound streams into one for output. It can also manage network-transparent audio. Obviously recommended for use in GNOME.

ALSA device(nbsp)(ndash) see the Audio output → ALSA subsection.

Local Playback Downmixing(nbsp)(ndash) enable use of downmixing or sound alteration for certain sound environments. You can set the way a multichannel audio will be downmixed when played inside Avidemux. If you have a 5.1 speaker soundsystem and an audio-device that supports it, you might want to select “no downmixing.” Otherwise the multichannel audio will be downmixed to either Dolby Pro Logic 1 or 2.

Volume bar controls:

• PCM: The non-master audio volume for your system. Most programs use the PCM audio as their control interface. This does not affect the whole system volume levels. This setting is generally recommended (unless you have some specific need to have Avidemux control your system volume, which is unlikely). This is often the Wave channel in your mixer.
• Master: The master audio volume for your system. This affect all audio levels in your system on every application. This setting is not recommended, though it is not harmful to use.

• GTK+: Uses no hardware acceleration for your video playback. Video playback may be choppy or unsmooth. Use of the option SDL or even better Xvideo accel if possible.
• SDL accel: Uses an abstract software layer system between your software and your hardware to improve video playback. It will smooth the video playback within Avidemux and provide a more reliable working enviroment. This option is better than normal GTK+, which has no acceleration. But XVideo accel is better if possible to use.
• XVideo accel: Uses the system video enviroment itself (not hardware) to improve video playback. It will smooth the video playback within Avidemux and provide a more reliable working enviroment. If this option is available, it should be used.

Post processing happens after the video frames have been created. Some users strongly recommend disabling all of these options as they can interfere with more complex operations, particularly with filtering involving interlacing and noise.

• Horizontal Deblocking: Enables minimal checking for broken video pixels blocks horizontally.
• Vertical Deblocking: Enables minimal checking for broken video pixels blocks vertically.
• Deringing: Enables minimal checking for subtle color distortion rings around contour lines in video.

See the Multithreading article.