Pierre-Louis Bossart wrote:

If you try to set the bits with ALSA controls in PulseAudio, somehow the settings are overwritten when the iec958 device is opened and initialized with default values.

That's how the iec958 device is intended to work.

The AES0..3 parameters of the iec958 device are the _only_ way to set these flags. If you don't set them, they get a static default value; see http://git.alsa-project.org/?p=alsa-lib.git;a=blob;hb=HEAD;f=src/conf/pcm/iec958.conf.

If PA wants to set these flags, it must do so when opening the device; any other mechanism will not work.

Regards, Clemens