SMPTE ST 299-2
Extension of the 24-Bit Digital Audio Format to 32 Channels for 3 Gb/s Bit-Serial Interfaces
|Publication Date:||21 July 2010|
SMPTE ST 299-2 defines an SMPTE 291M Type 1 packet structure for identifying audio channels numbered from 17 to 32, beyond the 16 channels defined in SMPTE ST 299-1. Four extended audio data packets and four extended audio control packets are identified. One of the extended audio control packets and one of the extended audio data packets is assigned to transport each of the four extended audio groups . Each extended audio group has four channels that carry up to four 24-bit audio channels with 32, 44.1, or 48-kHz sample rates, or up to two 24-bit audio channels with 96-kHz sample rate.
The purpose of defining four extended audio groups is to allow for multiplexing up to 32 audio channels into the horizontal ancillary (HANC) data space of the video source image formats mapped to a 3 Gb/s Level A serial data interface. The 3 Gb/s Level B serial data interface is capable of carrying 32 audio channels via application of SMPTE ST 299-1 to each of two 1.5 Gb/s SDI channels.
The format and location of audio data and control packets in the video data stream is identical to that of SMPTE ST 299-1, except for differences required to define extended audio groups.