DVDs can contain up to 8 audio tracks which This is most commonly used for different audio formats -- 5.1 DTS, 2.0 AC3, etc. -- as well as for commentary and audio tracks in different languages.

Language Settings:

It is possible to tag the tracks according to ISO-639, to indicate which language they represent. You can of course have multiple tracks with the same language code.

Since the language settings are valid per titleset and can not differ per PGC (Video file entry) these have to be synchronized to apply to the whole collection of videos in a titleset.

This is why once you have selected the audio file, you have to add a track and specify the language setting.

Note: The first track is ALWAYS reserved to the audio track assigned to the selected video.

Audio codecs :

The audio data on a DVD movie can be PCM, DTS, MPEG-1 Audio Layer II (MP2), or Dolby Digital (AC-3) format. In countries using the PAL system standard DVD-Video releases must contain at least one audio track using the PCM, MP2, or AC-3 format, and all standard PAL players must support all three of these formats. A similar standard exists in countries using the NTSC system, though with no requirement mandating the use of or support for the MP2 format. DTS audio is optional for all players, as DTS was not part of the initial draft standard and was added later; thus, many early players are unable to play DTS audio tracks. The vast majority of commercial DVD-Video releases today employ AC-3 audio.[citation needed] The official allowed formats for the audio tracks on a DVD Video are:

• PCM: 48 kHz or 96 kHz sampling rate, 16 bit or 24 bit L-PCM, 2 to 6 channels, up to 6144 kbit/s
• AC-3: 48 kHz sampling rate, 1 to 5.1 (6) channels, up to 448 kbit/s
• DTS: 48 kHz or 96 kHz sampling rate, 2 to 6.1 channels, Half Rate (768 kbit/s) or Full Rate (1536 kbit/s)
• MP2: 48 kHz sampling rate, 1 to 7.1 channels, up to 912 kbit/s