Using EC3SpecificBox information

Common information specific to Dolby Digital Plus is carried in these locations:

• EC3specificBox in the stsd atom
• BSI in the Dolby Digital Plus stream

The EC3SpecificBox is intended to be used by the system for information only. For example, the system might use the EC3SpecificBox for any of these scenarios:

• When informing the onscreen display of the channel configuration of the audio stream
• When offering the user the ability to select between the different audio services that are being carried (for example, in the case where multiple independent substreams are present)
• During recovery from errors (for example, if there is an interruption in audio data delivery and the system cannot ascertain the configuration of the complete Dolby Digital Plus bitstream from the substream structure in the MPEG-DASH sample due to CRC errors)

Because it is possible that differences may occur between the EC3SpecificBox and the parameters of the Dolby Digital Plus bitstream, this information must not be used to configure the audio decoder or the audio subsystem of the product. If the product encounters a conflict between the Dolby Digital Plus BSI values and the corresponding parameters in the EC3SpecificBox, the product must always use the values in the bitstream, because the BSI is more accurate.