Audio Configuration and Narrative Description Track Language
The first two characters denote the soundtrack configuration:
51 = 5.1
71 = 7.1 (Verify channel configuration with content provider.)
10 = 1.0 (Center Channel Mono)
20 = 2.0 (Stereo) Note: Only discrete audio should be used in a DCP; matrixed audio, such as Lt/Rt, should not be used.
MOS = No audio (Silent)
IAB = Immersive Audio Bitstream (SMPTE ST2098-2)
If present - and in this order separated by hyphens:
HI = Assisted Listening Track
VI = Audio Description Track
SL = Sign Language Track (ISDCF Document 13 - Sign Language Video Encoding for Digital Cinema)
Atmos, Auro, DTSX - Immersive Sound Formats
D-Box - Motion Simulator Formats
In the Composition Playlist
The Audio Configuration is listed at //Reel//CompositionMetadataAsset/MainSoundConfiguration:
1) The syntax for the Sound Configuration value includes qualifiers not shown in the example above; see SMPTE 429-16-2014 for details.
2) Permissible values for the SOUNDFIELD component of MainSoundConfiguration include the following listed in SMPTE 428-12: "51", "71", "SDS", "61", "M".
3) For silent compositions, either omit the MainSoundConfiguration element or append "/-" to the SOUNDFIELD, e.g. "71/-".
4) The MainSoundConfiguration element is a logical extension of the MainSound element in the composition playlist (the latter is a required element).
Many DCPs now contain supplementary tracks with an assisted listening track (enhanced dialog), and/or supplementary audio description tracks. In addition, sign language video may also be present, contained in an audio track. The presence of these tracks should be indicated in the Audio Type field as follows:
51-HI = 5.1 audio with a supplemental Assisted Listening track.
51-VI = 5.1 audio with a supplemental Audio Description track.
51-VI-SL = 5.1 audio with both supplemental Audio Description Description and Sign Language tracks.
51-HI-VI = 5.1 audio with both Assisted Listening and Audio Description tracks.
51-HI-VI-SL = 5.1 audio with Assisted Listening, Audio Description and Sign Language tracks.
It is important to note that there is not a specific language indicated in the Audio Type field for the HI, VI or SL tracks, since most often this language will be the same as the language indicated earlier in the naming string in the Audio Language field.