If I play my AC3 data on my HDAudio/SPDIF output using the hw:0,1 device, I can use alsamixer/amixer to mute/unmute.
Now if I use the iec958: plugin, I can't control the mute switch any longer:
Muting an AC-3 stream would require encoding a stream of silent PCM samples (no data is not the same as silence); therefore, the iec958 plugin disallows muting.
Actually the problem happens also with plain PCM rendered on the iec958 device.There's no way to use the IEC switch. So why do we have an S/PDIF switch in the first place? If it cannot be used when you sent IEC-formatted data (be that PCM or AC3-formatted data), then why bother? Allowing for mute doesn't have any impact on functionality, and it prevents the user from muting with alsamixer or a gui. I find this silly, or I am missing something.