SPDIF reads 17/48?

I recently got my new Rossini Player and Rossini Clock, and so far it’s great, but I notice something weird with SPDIF.

I have a US DISH Network box, and when I send PCM audio to the Rossini it first says 24/48, but after a second or so it changes to 17/48.

17?

The same is true if I connect via RCA (SPDIF1) or Toslink (SPDIF3.)

Is my Rossini confused?

My Mac sees the same source as 16/48.

Other SPDIF sources correctly show as 16/48.

I hear no weird audio artifacts as a result of this.

The likelihood is that the network dish box is actually outputting 17 bits. This is possible as SPDIF audio always transmits 24 bits for the audio signal. Sending a lower bit-depth signal with SPDIF means some of these bits simply won’t be used. The box is likely indicating 16-bit audio as the standard indicators for SPDIF are 16/20/24 bit.

Lots of products rely on the embedded information in SPDIF to determine sample rate and bit depth. A dCS product does this in a different way. It determines the bit depth by counting the active bits in the audio signal.

We do not look at the status bits to tell us what bit-depth the audio is, as this is often incorrect. Instead, we count the bits in the audio signal which actively toggle. Therefore, if the network dish box is outputting an SPDIF signal which has 17 audio bits toggling, it will report a 17-bit signal.

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That’s really neat, thanks for the explanation!