At AES 2009, Qualis Audio showed the digital input version of Sentinel, a network-based, automated surround-sound monitor that performs unattended monitoring of surround program material.
Sentinel goes beyond simplistic multichannel audio level metering, adding the ability to directly assess stereo and mono compatibility of a surround mix. The Sentinel performs stereo and mono downmixes internally and compares these to the original surround mix, flagging an error if content present in the surround mix is missing from either the stereo or mono mixes. The user is freed from continuously watching and interpreting a screen, allowing more attention to other aspects of producing, evaluating and transmitting the program.
The Sentinel also addresses audio problems such as intermittent or dead channels, incorrect signal routing or channel reversal. Catching these problems traditionally required continuous aural checks by skilled staff. The new digital input version adds the ability to catch problems unique to digital signals such as metadata errors, word length discrepancies and sample rate mismatch, allowing fully automated monitoring 24/7.
The Sentinel converts all measurements to a simple green/yellow/red "stoplight" display. Any of a user-defined list of error conditions (red light) may trigger an alarm. Alarm notification may be via traditional means such as audible sounder or contact closure and may also result in e-mails to multiple recipients.
Sentinel uses advanced signal-processing algorithms to directly answer broadcast user's fundamental questions, rather than merely displaying information requiring further analysis by experienced staff. Coupled with an intuitive interface and hardware designed to fit into existing infrastructure, the Sentinel allows significant reductions in operating costs while improving the quality of delivered audio.