Upmixing and Downmixing Two-channel Stereo Audio for Consumer Electronics

Abstract

In this comprehensive study, algorithms for upmixing, downmixing, and joint up/downmixing are examined and compared. Five upmixing algorithms based on signal decorrelation and reverberation are employed to convert two-channel stereo signals to jive-channel signals. For downmixing, methods ranging from mixing with simple gain adjustment to more sophisticated head related transfer function (HRTF) filtering and crosstalk cancellation system (CCS) are utilized to downmix the center channel and the surround channels into the available two frontal loudspeakers. For situations where only two-channel content and loudspeakers are available, a number of up/down mixing schemes are used to simulate a virtual surround environment. Emphasis of comparison is placed on two consumer electronic products: a 5.1 home theater system and a dual-loudspeaker MP3 handset. The effect of loudspeaker spacing on rendering performance is examined. Listening tests are conducted to compare the processing methods in terms of three levels of subjective indices. The results are processed by using the Multi-Analysis Of VAriance (MANOVA) to justify the statistical significance, followed by a multiple regression analysis to correlate the auditory preference with various timbral and spatial attributes.