BMW F01 Manual page 75

Using those channels, the sound tracks on a DVD can be played directly and entirely
independently on each individual channel. In combination, those sound tracks produce a
surround sound effect. For that reason, the process is described as discrete multichannel
playback.
There are normally two sound tracks recorded on a CD to reproduce the stereo signal,
the usual practice on a DVD is to use the 5.1 format with 6 sound tracks.
To adapt that format best to the vehicle environment (two rows of seats), it is converted
into 7.2 format and reproduced through seven mid-range/tweeter and two central bass
channels.
For multichannel playback, the Top-HiFi amplifier decodes the digital data from the data
source.
Multichannel audio formats can be played back both with the CIC player as well as the
DVD changer.
The following multichannel audio formats are supported:
• Dolby Digital Surround
• Dolby Digital Surround Ex
• DTS (Digital Theater System)
• DTS-ES (Digital Theater System-Extended Surround)
The multichannel audio format is indicated on the DVD case.
The Top-HiFi amplifier supports Dolby Pro Logic II for calculating the spatial sound
information from an existing stereo signal.
This process replaces Logic 7 known from other BMW vehicles. A surround sound effect
can be computed from the stereo signal, which consists only of a left and right channel.
The signals of the individual channels are output with time correction from the 16
available speakers of the Top-HiFi system in the F01/F02. This produces a homogeneous
sound effect for the listener in 7.2 format.
Audio playback can also be adjusted by the customer through the iDrive with the aid of
the 7 channel equalizer integrated in the Top-HiFi amplifier.
After signals have been processed, the audio signals are forwarded as analog low
frequency signals to the speakers.
The Top-HiFi amplifier supports speed-dependent equalization in addition to speed-
dependent volume control. The effect is that the frequency response is adjusted in
relation to the speed of the vehicle.
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F01 Audio Systems