Determining sound locations in multi-channel audio

A system for processing multi-channel audio, the system comprising:

• at least one processor configured to:
• receive a multi-channel audio signal representing a sound, each channel of the multi-channel audio signal configured to provide audio associated with a corresponding channel position around a perimeter of a soundstage;
• determine a time-varying volume level for each channel of the multi-channel audio signal;
• determine, from the time-varying volume levels and the channel positions, a time-varying position in the soundstage of the sound by determining an estimated position vector, the estimated position vector failing within a polygonal shape in the soundstage;
• and
• generate a location data signal representing the time-varying position of the sound;
• wherein the soundstage is circular, the channel positions are time-invariant and are located at respective azimuthal positions around a circumference of the soundstage;
• wherein a center of the soundstage corresponds to a listener position;
• wherein the multi-channel audio signal includes a front center channel that is designated for audio that is not pannable;
• and
• wherein the at least one processor is further configured to determine the polygonal shape by linearly connecting each time-invariant channel position with its adjacent time-invariant channel positions except for the front center channel, such that the time-invariant channel positions directly adjacent to the front center channel linearly connect with the center of the soundstage.

A system for processing multi-channel audio, the system comprising:

• at least one processor configured to:
• receive a multi-channel audio signal representing a sound, each channel of the multi-channel audio signal configured to provide audio associated with a corresponding channel position around a perimeter of a soundstage;
• determine a time-varying volume level for each channel of the multi-channel audio signal;
• determine, from the time-varying volume levels and the channel positions, a time-varying position in the soundstage of the sound;
• generate a location data signal representing the time-varying position of the sound;
• and
• detect an event in the multi-channel audio signal, the event detection including:
• determining that a magnitude of the time-varying position has exceeded a specified magnitude threshold for at least a specified duration;
• summing the channels of the multi-channel audio signal and applying a high-pass filter to form a filtered mono signal;
• smoothing a volume of the filtered mono signal with a filter that has a slow attack and a fast release to form a smoothed volume level;
• during the specified duration, determining that a volume of the filtered mono signal exceeds the smoothed volume level;
• and
• generating an event detection data signal representing the time during which the event is detected.

A method for processing multi-channel audio, the method comprising:

• receiving a multi-channel audio signal representing a sound, each channel of the multi-channel audio signal configured to provide audio associated with a corresponding channel position around a perimeter of a soundstage;
• determining a time-varying volume level for each channel of the multi-channel audio signal;
• determining, from the time-varying volume levels and the channel positions, a time-varying estimated position vector that represents an estimated position in the soundstage of the sound;
• scaling a magnitude of the estimated position vector;
• scaling an azimuthal angle of the estimated position vector to adjust front-to-back symmetry, such that a test position vector corresponding to a case of independent pink noise having equal volume in all channels is scaled to fall substantially at the center of the soundstage;
• and
• generating, from the scaled magnitude and scaled azimuthal angle, a location data signal representing the time-varying position of the sound.

A system for processing multi-channel audio, the system comprising:

• at least one processor configured to:
• receive a multi-channel audio signal representing a sound, each channel of the multi-channel audio signal configured to provide audio associated with a corresponding time-invariant channel position around a circumference of a circular soundstage, the time-invariant channel positions being located at respective azimuthal positions around the circumference of the soundstage, a center of the soundstage corresponding to a listener position;
• determine a time-varying volume level for each channel of the multi-channel audio signal;
• determine, from the time-varying volume levels and the time-invariant channel positions, an estimated position vector, the estimated position vector falling within a polygonal shape in the soundstage;
• radially scale the estimated position vector, such that estimated position vectors falling on an edge of the polygon shape are scaled to fall on the circumference of the soundstage, and estimated position vectors falling in an interior of the polygon shape are scaled to increase a magnitude of the estimated position vector;
• azimuthally scale the estimated position vector to adjust front-to-back symmetry such that position vectors of independent pink noise having equal volume in all the channels are scaled to fall at the center of the soundstage;
• form a time-varying position from the radially and azimuthally scaled estimated position vector;
• and
• generate a location data signal representing the time-varying position of the sound.