Dolby Digital: Dolby Digital is available in different formats 1.0, 2.0, ..., 5.1. The place after the dot indicates whether a Channel for Subwoofer exists (0 = none, 1 = there is a channel). 1.0 means mono, 2.0 means stereo, 5.1 means Left, Center, Right, Surround Left, Surround Right, Subwoofer.
Abbreviated channel designations: L, C, R, SL, SR, LFE.
The sampling frequency is 48 kHz with a maximum of 24 bits. The bitrate varies from 64 kbps up to 448 kbps. 384 kbps is the normal rate for 5.1 and 192 kbps for stereo.
Lossy compression compresses by a factor of 12.
The subwoofer channel, if present, goes from 3 to 120 Hertz, whereby the 3 Hz is an optional requirement, ie not everyone will stick to it. This format has been around since 1992.