Switching Audio Tracks in MKV Files with MPlayer

MKV (Matroska) containers frequently contain multiple audio tracks. You can cycle through them during playback using keyboard shortcuts.

Using mplayer

Press # to cycle through available audio tracks while the video is playing. This works for MKV, AVI, MPEG, and other container formats that mplayer supports.

mplayer video.mkv
# Then press # during playback to switch tracks

You can also specify which audio track to play from the command line:

mplayer -aid 1 video.mkv    # Play first audio track
mplayer -aid 2 video.mkv    # Play second audio track

The -aid option takes a 1-based track number. Use mplayer -identify video.mkv to list available audio tracks and their IDs.

Modern alternatives

mplayer is largely unmaintained. Consider mpv instead — it’s actively developed, handles MKV better, and offers superior codec support:

mpv video.mkv
# Press 'j' to cycle audio tracks during playback

Specify a track directly:

mpv --aid=1 video.mkv

List all tracks before playing:

mpv --sid=no video.mkv    # Show track info without playing

Using ffmpeg to inspect or extract tracks

To see what audio tracks are in an MKV file:

ffprobe -v error -select_streams a -show_entries stream=index,codec_name,language video.mkv

Extract a specific audio track:

ffmpeg -i video.mkv -map 0:a:1 -c copy audio_track2.aac

Replace the audio track entirely:

ffmpeg -i video.mkv -i new_audio.aac -c:v copy -c:a aac -map 0:v:0 -map 1:a:0 output.mkv

Using mkvtoolnix for direct MKV manipulation

If you need to permanently change which audio track plays by default, use mkvtoolnix:

mkvpropedit video.mkv --edit track:a1 --set flag-default=1
mkvpropedit video.mkv --edit track:a2 --set flag-default=0

This sets track a1 (first audio) as the default without re-encoding.

VLC as a GUI option

If you prefer a graphical interface:

vlc video.mkv
# Use Audio menu → Audio Track to switch

Quick reference

Tool	Cycle tracks	Set track	Extract track
mplayer	# key	-aid 1	N/A (use ffmpeg)
mpv	j key	--aid=1	N/A (use ffmpeg)
ffmpeg	N/A	N/A	-map 0:a:1
mkvtoolnix	N/A	mkvpropedit	mkvextract

For most workflows, mpv is the best choice — it’s modern, actively maintained, and handles complex containers reliably.

Quick Reference

This article covered the essential concepts and commands for the topic. For more information, consult the official documentation or manual pages. The key takeaway is to understand the fundamentals before applying advanced configurations.

Practice in a test environment before making changes on production systems. Keep notes of what works and what does not for future reference.

Additional Tips and Best Practices

When implementing the techniques described in this article, consider these best practices for production environments. Always test changes in a non-production environment first. Document your configuration changes so team members can understand what was modified and why.

Keep your system updated regularly to benefit from security patches and bug fixes. Use package managers rather than manual installations when possible, as they handle dependencies and updates automatically. For critical systems, maintain backups before making any significant changes.

Quick Verification

After applying the changes described above, verify that everything works as expected. Run the relevant commands to confirm the new configuration is active. Check system logs for any errors or warnings that might indicate problems. If something does not work as expected, review the steps carefully and consult the official documentation for your specific version.