## Audio data

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

| Linear PCM | Dolby Digital AC-3 | Mpeg1 | Mpeg2 | DTS | SDDS
Sample Freq | 48kHz 98kHz | 32kHz 44.1kHz 48kHz | 48kHz | 48kHz | 48kHz | 48kHz
Resolution | 16, 20, 24 | Compressed | Compressed | Compressed | Compressed | Compressed
Max Bitrate | 6144 kbps | 448 kbps | 384 kbps | 912 kbps | 1536 kbps | 1280 kbps
Max number of channels | 8 | 5.1 | 2 | 7.1 | 5.1 | 7.1

Description

Pulse Code Modulation

- Same as CD auudio format.
- No compression
- Stereo soud track
- Uses more storage due to the uncompressed format

Dolby Digital AC-3

- Uses psycho acoustic or perceptual compression
- There are six flavours of Dolby Digital audio streams :

Dolby Digital Mono

Dolby Digital Stereo

Dolby Digital Surround

Dolby Digital 4.0

Dolby Digital 5.0

Dolby Digital 5.1

MPEG audio

- Provides up to 8 channels of sound, where the 7'th and 8'th channels are called Left-Center and Right-Center (this is a 7.1 configuration)
- The sound quality os similar to that of AC-3 streams
- Only Mpeg2 Layer II audio streams are allowed for Video DVDs
- The sampling rate must be 48kHz
- Note: Mpeg2 audio streams are incompatible with NTSC and only valid for PAL !

Digital Theater System

- Originally developed for movie theaters.
- Discrete 5.1 channel soundtrack
- Must be played through DTS equipment

Sony Dynamic Digital Sound

- Originally developed for movie theaters
- Discrete 5.1 or 7.1 channels
- No currently available DVD system support SDDS for DVD-Video