Volume control for audio signals

Abstract

A motion picture soundtrack reproduction system has a center front soundtrack channel and a plurality of other soundtrack channels. A volume control adjusts the gain of all the channels. The volume control has a range of settings from a minimum to a maximum, the gain of the center front channel having substantially a first relationship to the volume control settings and the gain of the other channels having substantially a second relationship to the volume control settings, the relationships being such that for a range of volume control settings less than a first setting the gain of the center front channel remains substantially constant while the gain of the other channels decreases as the setting decreases or decreases more gradually than the gain of the other channels as the setting decreases.

The invention claimed is: 
     
       1. A motion picture soundtrack reproduction system, the system having a center front soundtrack channel and a plurality of other soundtrack channels, comprising
 a controller having a volume control for adjusting the gain of all the channels, the volume control having a range of settings from a minimum to a maximum, the controller having a first output for controlling the gain of the center front channel and a second output for controlling the gain of the other channels in response to settings of the volume control, the gain of the center front channel having a first relationship to the volume control settings and the gain of the other channels having a second relationship to the volume control settings, the relationships being such that for a range of volume control settings less than a first setting the gain of the center front channel (1) remains substantially constant while the gain of the other channels decreases as the setting decreases, or (2) decreases more gradually than the gain of the other channels as the setting decreases.   
     
     
       2. A motion picture soundtrack reproduction system, comprising
 a center front soundtrack channel and a plurality of other soundtrack channels, each of said channels having adjustable gain and one or more loudspeakers, and   a controller having a volume control for adjusting the gain of all the channels, the volume control having a range of settings from a minimum to a maximum, the controller having a first output for controlling the gain of the center front channel and a second output for controlling the gain of the other channels in response to settings of the volume control the gain of the center front channel having a first relationship to the volume control settings and the gain of the other channels having a second relationship to the volume control settings, the relationships being such that for a range of volume control settings less than a first setting the gain of the center front channel (1) remains substantially constant while the gain of the other channels decreases as the setting decreases or (2) decreases more gradually than the gain of the other channels as the setting decreases.   
     
     
       3. A system according to  claim 1  or  claim 2  wherein the range of volume control settings less than said first setting extends down to the minimum control setting. 
     
     
       4. A system according to  claim 1  or  claim 2  wherein the range of volume control settings less than said first setting extends down to a second setting above the minimum control setting. 
     
     
       5. A system according to  claim 3  wherein for settings less than said second setting the gains of all the channels decrease in substantially the same way as the setting decreases and for such volume control settings the gain of the center front channel is greater than the gain of the other channels. 
     
     
       6. A system according to  claim 5  wherein for settings less than said second setting the gain of the center front channel is greater than the gain of the other channels by a substantially constant amount in the logarithmic domain. 
     
     
       7. A system according to  claims 1  wherein for settings greater than said first setting the gains of all the channels increase as the setting increases and for each of such volume control settings the gain of the center front channel and the gain of the other channels are substantially the same. 
     
     
       8. A system according to  claims 1  wherein when the volume control is set to a standard setting, each of the channels has a respective gain that produces a respective standard acoustic level in response to a signal having a respective standard reference level in the channel. 
     
     
       9. A system according to  claim 8  wherein said first setting is about said standard setting. 
     
     
       10. A method, comprising:
 processing an audio signal by adjusting a gain of a first channel of the audio signal and a gain of a second channel of the audio signal with respect to a control feature setting, the gain of the first channel is adjusted at a first relationship to the gain of the second channel as settings of the control feature are above a first threshold level and the gain of the first channel is adjusted at a second relationship to the gain of the second channel as settings of the control feature are below a second threshold level, the first relationship different from the second relationship;   wherein the method is performed by one or more computing devices.   
     
     
       11. The method of claim 10, wherein the adjusting employs digital controls. 
     
     
       12. The method of claim 11, wherein the digital controls use a first lookup table to adjust the gain of the first channel and a second lookup table to adjust the gain of the second channel. 
     
     
       13. The method of claim 10, wherein the control feature is a volume control. 
     
     
       14. The method of claim 10, wherein the second channel is at least one of a left channel, right channel, and surround channel. 
     
     
       15. The method of claim 10, wherein the audio signal is in a Dolby Digital format. 
     
     
       16. The method of claim 10, wherein the audio signal is a digital audio signal. 
     
     
       17. The method of claim 10, wherein first channel is a center channel. 
     
     
       18. The method of claim 10, wherein the audio signal is a multitrack digital soundtrack. 
     
     
       19. An apparatus, comprising:
 a subsystem, implemented at least partially in hardware that processes an audio signal by adjusting a gain of a first channel of the audio signal and a gain of a second channel of the audio signal with respect to a control feature setting, the gain of the first channel is adjusted at a first relationship to the gain of the second channel as settings of the control feature are above a first threshold level and the gain of the first channel is adjusted at a second relationship to the gain of the second channel as settings of the control feature are below a second threshold level, the first relationship different from the second relationship.   
     
     
       20. The apparatus of claim 19, wherein the processing subsystem employs digital controls. 
     
     
       21. The apparatus of claim 20, wherein the digital controls use a first lookup table to adjust the gain of the first channel and a second lookup table to adjust the gain of the second channel. 
     
     
       22. The apparatus of claim 19, wherein the control feature is a volume control. 
     
     
       23. The apparatus of claim 19, wherein the second channel is at least one of a left channel, right channel, and surround channel. 
     
     
       24. The apparatus of claim 19, wherein the audio signal is in a Dolby Digital format. 
     
     
       25. The apparatus of claim 19, wherein the audio signal is a digital audio signal. 
     
     
       26. The apparatus of claim 19, wherein first channel is a center channel. 
     
     
       27. The apparatus of claim 19, wherein the audio signal is a multitrack digital soundtrack. 
     
     
       28. A non-transitory computer readable medium, storing software instructions, which when executed by one or more processors cause performance of the steps of:
 processing an audio signal by adjusting a gain of a first channel of the audio signal and a gain of a second channel of the audio signal with respect to a control feature setting, the gain of the first channel is adjusted at a first relationship to the gain of the second channel as settings of the control feature are above a first threshold level and the gain of the first channel is adjusted at a second relationship to the gain of the second channel as settings of the control feature are below a second threshold level, the first relationship different from the second relationship.   
     
     
       29. The non-transitory computer readable medium of claim 28, wherein the adjusting employs digital controls. 
     
     
       30. The non-transitory computer readable medium of claim 29, wherein the digital controls use a first lookup table to adjust the gain of the first channel and a second lookup table to adjust the gain of the second channel. 
     
     
       31. The non-transitory computer readable medium of claim 28, wherein the control feature is a volume control. 
     
     
       32. The non-transitory computer readable medium of claim 28, wherein the second channel is at least one of a left channel, right channel, and surround channel. 
     
     
       33. The non-transitory computer readable medium of claim 28, wherein the audio signal is in a Dolby Digital format. 
     
     
       34. The non-transitory computer readable medium of claim 28, wherein the audio signal is a digital audio signal. 
     
     
       35. The non-transitory computer readable medium of claim 28, wherein first channel is a center channel. 
     
     
       36. The non-transitory computer readable medium of claim 28, wherein the audio signal is a multitrack digital soundtrack.