Spatial Audio Processing: MPEG Surround and Other Applications

6.5 Subjective evaluation

During the MPEG Surround development, the progress and corresponding performance have been documented in detail in several publications [49, 121, 122, 265] and documented in a formal verification test report [144]. The results published in those papers primarily focused on bitrate scalability, different channel configurations, support for external down mixes, and binaural decoding (see also Chapter 8).

The purpose of the listening tests described in this chapter is to demonstrate that existing stereo services can be upgraded to high-quality multi-channel audio in a fully backward compatible fashion at transmission bit rates that are currently used for stereo. In a first test, the MPEG Surround performance is demonstrated using two different core coders (AAC and MP3), and a comparison is made against alternative systems to upgrade a stereo transmission chain to multi-channel audio. In a second test, the performance for the operation mode without transmission of spatial parameters (i.e. using the enhanced matrix mode) is outlined.

6.5.1 Test 1: operation using spatial parameters

Stimuli and method

The list of codecs that were employed in the test is given in Table 6.2. The total employed bit rate (160 kbps) was set to a value that is commonly used for high-quality stereo transmission.

Configuration (1) represents stereo AAC at 128 kbps in combination with 32 kbps of MPEG Surround (MPS) parametric data. Configuration (2) is based on a different core coder ...