47.6.1 Protocol

The SPDIFRX protocol is defined in IEC-60958 standard.

Data is performed by the transfer of blocks of 192 frames.

Each frame is divided into two subframes, one for each channel.

Each subframe is divided into 32 time slots carrying the following fields:

• Preamble (4 bits)–Three possible preambles named B, M and W. Preambles are specific patterns providing synchronization and identification of the subframes and blocks.
• Data (24 bits)–Can carry a PCM audio data or non-PCM data streams.
• Validity bit
• User data bit
• Channel status bit
• Parity bit–Ensures that time slots 4 to 31 carry an even number of ones and an even number of zeros.
  Note: The data field may carry 16-bit, 20-bit or 24-bit data.