Patent Application
20090060208
This disclosure relates to manipulating spatial processing in a vehicle audio system that is used to radiate entertainment audio and announcement audio.
In one aspect, a vehicle audio system includes a source of audio signals, which may include both entertainment audio signals and announcement audio signals, speakers for radiating audio signals, and spatial enhancement circuitry comprising circuitry to avoid applying spatial enhancement processing to the announcement audio signals. The spatial enhancement circuitry may apply no spatial processing operations to the audio signals received from the source if there is announcement audio content in the audio signals received from the source. The spatial enhancement circuitry may include first alternately selectable circuitry for applying the spatial enhancement processing to the audio signals, second alternately selectable circuitry for applying no spatial enhancement processing to the audio signals, and circuitry for selecting the audio signals from the first or second alternately selectable circuitry based on the presence of announcement audio signal in the combined audio signals. The spatial enhancement circuitry may include circuitry for separating the audio signals from the audio signal source into entertainment audio signals and announcement audio signals, circuitry for applying spatial enhancement processing to the entertainment audio signals, and circuitry for combining the processed entertainment audio signals and the announcement audio signals. The source of audio signals may include a source of front audio signals that may contain front announcement audio signals, hereinafter referred to as front audio signals, and a source of rear audio signals that may contain rear announcement audio signals, hereinafter referred to as rear audio signals and the audio system may further include front spatial processing circuitry including first alternately selectable front circuitry for applying the spatial enhancement processing to the front audio signals, second alternately selectable front circuitry for applying no spatial enhancement processing to the front audio signals, and circuitry for selecting the audio signals from the first or second alternately selectable front circuitry based on the presence of announcement audio signal in the front audio signals. The audio may further include rear spatial processing circuitry that includes first alternately selectable rear circuitry for applying the spatial enhancement processing to the rear audio signals, second alternately selectable rear circuitry for applying no spatial enhancement processing to the rear audio signals, and circuitry for selecting the audio signals from the first or second alternately selectable circuitry rear based on the presence of announcement audio signal in the rear audio signals. The spatial enhancement circuitry may apply spatial enhancement processing to the entertainment audio signals and not apply spatial enhancement processing to the announcement audio signals.
In another aspect, a method for operating a vehicle audio system includes receiving audio signals that may contain announcement audio signals; if the received audio signals do not contain announcement audio signals, the method includes applying spatial processing to the received audio signals; and if the received audio signals include announcement audio signals, the method does not apply spatial processing to the announcement audio signals. The method may include, if the received audio signals include announcement audio signals and entertainment audio signals, applying spatial processing to the entertainment audio signals.
In another aspect, a vehicle audio amplifier includes an input terminal for receiving audio signals that may include announcement audio signals and spatial enhancement circuitry containing circuitry to avoid applying spatial enhancement processing to the announcement audio signals. The spatial enhancement circuitry may apply no spatial processing operations to the received audio signals if the received audio signals include announcement audio signals. The spatial enhancement circuitry may include first alternately selectable circuitry for applying the spatial enhancement processing to the combined audio signals, second alternately selectable circuitry for applying no spatial enhancement processing to the combined audio signals; and circuitry for selecting the audio signals from the first or second alternately selectable circuitry based on the presence of announcement audio signals in the combined audio signals. The spatial enhancement circuitry may include circuitry for separating the combined audio signals into entertainment audio signals and announcement audio signals, circuitry for applying spatial enhancement processing to the entertainment audio signals, and circuitry for combining the processed entertainment audio signals and the announcement audio signals. The input terminal may include an input terminal for receiving front audio signals that may include announcement audio signals, hereinafter referred to as front input terminal and an input terminal for receiving rear audio signals which may include announcement audio signals, hereinafter referred to as rear input terminal. The amplifier may further include front spatial processing circuitry including first alternately selectable front circuitry for applying the spatial enhancement processing to the front audio signals, second alternately selectable front circuitry for applying no spatial enhancement processing to the front audio signals, and circuitry for selecting the audio signals from the first or second alternately selectable front circuitry based on the presence of announcement audio signal in the front audio signals, and the audio system may further include rear spatial processing circuitry including first alternately selectable rear circuitry for applying the spatial enhancement processing to the rear audio signals, second alternately rear selectable circuitry for applying no spatial enhancement processing to the rear audio signals, and circuitry for selecting the audio signals from the first or second alternately selectable rear circuitry based on the presence of announcement audio signal in the rear audio signals.
Referring to
The head unit 120 provides to amplifier 140 both the entertainment audio and announcement audio when present. The amplifier 140 include circuitry for applying spatial enhancement processing to the audio signal to enhance the presentation of entertainment audio inside the vehicle cabin. Spatial enhancement can include adding channels, such as center or surround channels, or other processing that can affect the spatial characteristics of the audio system, for example by “widening” the sound stage by modifying inter-aural crosstalk.
When announcement audio is present in a combined audio signal, spatially enhancing the combined entertainment and announcement audio signal can lead to undesirable audible artifacts. For example, the resulting audio presentation may include distorted sound, or bleeding of the announcement audio into entertainment audio. Similarly, the spatial enhancement processing could direct the pertinent audio signal so that the perceived source is in an illogical direction in relation to a listener's location.
In one particular example, a vehicle chime for reminding the car's occupants to fasten their seatbelt may sound as if it comes from the rear of the vehicle if certain spatial enhancement processing is applied to the signal. If this chime comes from the rear instead of the dashboard, occupants may be confused as to the meaning of the clime because most people are accustomed to warning/reminder chimes coming from the dashboard area of the vehicle. Misdirected signaling can be particularly concerning when audio signal is intended as a reminder or warning for the driver of a vehicle.
To reduce such audible artifacts the amplifier 140 contains circuitry that avoids applying to the spatial processing operations to announcement audio.
The head unit 120 also includes fader controls (not shown) that permit a user to control the relative volume between the front (302, 303, 304) and rear speakers (306, 308). For example, the user can manipulate the fader control to direct audio to be faded to the rear speakers only. However, in some implementations, the amplifier 140 directs announcement audio to the appropriate speaker to maintain the intended location of the announcement audio despite the fader setting. For example, if a a DVD movie is playing for children in the rear seat, a parent may fade adjust the fade control so that the entertainment audio is directed completely to rear speakers (306, 308). However if a cellular phone connected to (or integrated within) the entertainment system 100 sends a ring chime signal to the amplifier 340, the amplifier 340 will present the ring chime in one or more of the front speakers (e.g., speaker 302, 303 and/or 304).
The processing of announcement audio can be done in at least two ways: a bypass mode and an extraction mode.
For example, as shown in
The crossfader 330 also may process the selected signal so that transition from selection of one branch to another is smooth. The output matrixer then directs the audio signals to the appropriate speakers.
As shown in
In systems in which the head unit transmits a front audio signal and a rear audio signal and inserts announcement audio in the front audio signal only, the announcement audio extractor 310 may compare the front audio signal and the rear audio signal and extract the difference between the front audio signal and the rear audio signal to determine the announcement audio content.
Referring to
Though the elements of several views of the drawing may be shown and described as discrete elements in a block diagram and may be referred to as “circuitry”, unless otherwise indicated, the elements may be implemented as one of, or a combination of, analog circuitry, digital circuitry, or one or more microprocessors executing software instructions. The software instructions may include digital signal processing (DSP) instructions. Unless otherwise indicated, signal lines and terminals may be implemented as discrete analog or digital signal lines or terminals, as a single discrete digital signal line or terminal with appropriate signal processing to process separate streams of audio signals, or as elements of a wireless communication system. Some of the processing operations maybe expressed in terms of the calculation and application of coefficients. The equivalent of calculating and applying coefficients can be performed by other analog or digital signal processing techniques and are included within the scope of this patent application. Unless otherwise indicated, audio signals or video signals or both may be encoded and transmitted in either digital or analog form; conventional digital-to-analog or analog-to-digital converters nay be omitted in some figures. Audio signal processing (for example equalization) that does not significantly affect the spatial characteristics of the audio is omitted from the figures. For simplicity of wording “radiating acoustic energy corresponding to entertainment audio signals” may be referred to as “radiating entertainment audio signals”, and “radiating acoustic energy corresponding to announcement audio signals may be referred to as “radiating announcement audio signals.”
A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.
