Audio Formats Supported by the DVD Specification and DVD Studio Pro

The following audio formats are supported by the DVD specification and can be imported into DVD Studio Pro without using the embedded AIFF encoder.

Note: When importing DVD-compliant audio files, DVD Studio Pro imports only elementary files (not multiplexed). See Elementary and Multiplexed MPEG Files for more information.

Uncompressed PCM Audio

Uncompressed audio is typically referred to as PCM, although the files usually have a “.wav” or “.aif” extension. The DVD specification supports uncompressed PCM audio at sample sizes of 16 bits and 24 bits and sample rates of 48 kHz or 96 kHz. Audio in this format is completely compatible with DVD players worldwide and is of higher fidelity than data-compressed audio. The disadvantage of PCM audio is the relatively large file sizes, compared to compressed audio formats.

There are two common PCM audio formats:

  • AIFF audio (Audio Interchange File Format-uncompressed PCM audio; the most common Macintosh audio format)

  • WAVE audio (Windows uncompressed PCM audio; the most common Windows audio format, also referred to as WAV)

The DVD Studio Pro integrated MPEG encoder creates AIFF format files. In most cases, DVD Studio Pro converts WAVE files into AIFF files.

Compressed Audio Formats

The DVD medium uses data-compressed (as opposed to sonically compressed) audio for two purposes:

  • To deliver discrete surround audio (5.1)

  • To conserve bandwidth and disc space, allowing more room for video. This is especially applicable in long-form material such as feature films, notably when the smaller DVD-5 medium is the target.

Data-compressed audio for DVD comes in a few forms, described next.

MPEG-1 Layer 2 Audio

For DVD products in PAL, MPEG-1 Layer 2 audio is compatible with all players. For NTSC markets (North America, Japan), most (but not all) DVD players support playback of MPEG-1 Layer 2 audio. If you create NTSC titles using MPEG audio, be aware that there may be problems in playback on some players.

If you want to ensure that your data-compressed audio is compatible with all players for NTSC, using the AC-3 format is recommended. See the next section for information on encoding and authoring with AC-3 format audio.

Dolby Digital AC-3 Audio

There are two good reasons to use AC-3 format audio in your DVD production:

  • To take advantage of 5.1 surround audio (five main speakers and a subwoofer—six channels of audio total), which is supported by AC-3 but not by MPEG-1 Layer 2

  • To produce stereo data-compressed audio that is fully compatible with every DVD player in the NTSC markets of North America and Japan. You may run into some compatibility issues with older DVD players in PAL countries.

You can use the AC-3 encoder in Compressor to encode everything from stereo to 5.1 surround audio. See Previewing AC-3 and DTS Audio for information on listening to surround audio.

DTS Audio

DTS (Digital Theatre Systems) is an alternative format for surround audio. DVD Studio Pro can import and use DTS audio files.

DVD Studio Pro supports DTS ES audio that can have up to 6.1 channels as well as audio that uses either a 48 kHz or a 96 kHz sample rate and a 24-bit sample size.

Important: All DTS audio imported into DVD Studio Pro must use the compacted file format, with a “.cpt” file extension. Additionally, DTS audio using a 44.1 kHz sample rate will produce unusable results.

See Previewing AC-3 and DTS Audio for information on listening to surround audio.

Previewing AC-3 and DTS Audio

In most cases, the best way to verify AC-3 and DTS audio is to burn a disc that you can play on a DVD player with suitable audio support. If you play the audio on your computer using its built-in audio support, the following happens:

  • When you play AC-3 audio from the Assets tab, one of the editors (Track, Story, Slideshow, or Menu Editor), or the Simulator, the audio is automatically converted to two-channel stereo for playback through your computer.

  • Because there is no DTS decoder on your computer, you cannot hear DTS audio when played from the Assets tab, one of the editors (Track, Story, Slideshow, or Menu Editor), or the Simulator.

You are able to add an external AC-3 or DTS decoder to your computer to listen to your surround sound audio from the Assets tab, one of the editors (Track, Story, Slideshow, or Menu Editor), or the Simulator.

To configure DVD Studio Pro to use an external audio monitor
  1. Choose DVD Studio Pro > Preferences.

  2. Click the Simulator icon to show the Simulator preferences.

  3. Choose your external audio monitor device from the Playback Output section’s Audio pop-up menu.

    Common choices include Built-in Audio, for normal system audio, and Built-in Audio (S/PDIF), which uses your system’s optical digital audio output (if available) to output the audio to an external AC-3 or DTS decoder.

  4. Click Apply.

See External Video and Audio Monitoring for more information.

Another option is to build your project and use the Apple DVD Player. Similar to DVD Studio Pro, you can configure DVD Player to use an external audio monitor.

To configure DVD Player for external audio decoder support
  1. Open DVD Player.

  2. Choose DVD Player > Preferences.

  3. Click the Disc Setup icon to show the Disc Setup pane.

  4. Choose the external audio device to use from the Audio Output pop-up menu.

  5. Click OK.