In SD-SDI mode, as per SMPTE ST 272, up to 16 channels of audio are inserted on data stream 1. In HD-SD mode, as per SMPTE ST 299-1, up to 16 channels of audio are inserted onto data streams 1 and 2. In 3G, 6G and 12G SDI modes, as per SMPTE 299-1 and SMPTE ST 299-2, up to 32 channels of audio are inserted onto data streams 1, 2, 3 and 4. Audio control packets are inserted on data stream 1 and 3 (Y Video In) and audio data packets are inserted on data stream 2 and 4 (CBCR Video In). Remaining data streams from SDI Transmitter are delayed to match the latency of the audio insertion. Audio embedded and latency matched data streams are sent back to the SDI Transmitter for further processing.
The figure below highlights the maximum number of audio channels that can be embedded in each SDI mode as per the SDI specification. Audio multiplexers working on data stream 1, 2, 3, and 4 embeds a maximum of 32 audio channels.
