AC-3 realtime encoding for your (old) amp under Ubuntu? No problemo – these days.
Task: connect the PC to the amp, efficiently. AC-3 via optical cabel came in my mind – no noise.
Solution: the a52 library! Specialised hardware like Soundstorm is not necessary. Good, good…
So we install the asound plugin including a52 and pavucontrol for better access of the settings.
The right source has to be set in pavucontrol (e.g. Built-in Audio Digital Stereo with port Digital Output (S/PDIF) ) and the checkbox AC3 to be activated.
BAM! Stereo Dolby Digital on your amp. I didn’t test surround upmixing, but it’s mostly not suitable.