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 snore 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 for volume control of audio signals, comprising:
 reducing a setting of a volume control in response to a first element of an audio signal, the setting ranging from a minimum to a maximum;   in response to the reducing, adjusting a gain of a first channel of a second element of the audio signal and a gain of a second channel of the second element of the audio signal, for a range of volume control settings less than a first setting the adjusting both decreases loudness and increases a contribution of the first channel to the loudness of a reproduced second element of the audio signal, for a range of volume control settings less than a second setting the adjusting decreases the gain of the first channel in a substantially same manner as the gain of the second channel is decreased as the setting of the volume control is reduced;   feeding an audio signal of the first channel to a first output;   feeding an audio signal of the second channel to a second output;   wherein the first element of the audio signal and the second element of the audio signal are different elements within the audio signal.    
     
     
       11. The method of claim 10, wherein the reducing employs digital controls.  
     
     
       12. The method of claim 10, wherein the second output is at least one of a left output, right output, and surround output.  
     
     
       13. The method of claim 10, wherein first output is a center channel output.  
     
     
       14. The method of claim 10, wherein the first element of the audio signal is a trailer and the second element of the audio signal is a feature film.  
     
     
       15. The method of claim 10, wherein the first element of the audio signal and the second element of the audio signal are in a Dolby Digital format.  
     
     
       16. The method of claim 10, wherein the first element of the audio signal and the second element of the audio signal are digital streams.  
     
     
       17. The method of claim 10, wherein the first element of the audio signal and the element of the audio signal are multitrack digital soundtracks.  
     
     
       18. An apparatus for volume control of audio signals, comprising:
 a subsystem, implemented at least partially in hardware that reduces a setting of a volume control in response to a first element of an audio signal, the setting ranging from a minimum to a maximum;   a subsystem, implemented at least partially in hardware that, in response to the reducing, adjusts a gain of a first channel of a second element of the audio signal and a gain of a second channel of the second element of the audio signal, for a range of volume control settings less than a first setting the adjusting both decreases loudness and increases a contribution of the first channel to the loudness of a reproduced second element of the audio signal, for a range of volume control settings less than a second setting the adjusting decreases the gain of the first channel in a substantially same manner as the gain of the second channel is decreased as the setting of the volume control is reduced;   a subsystem, implemented at least partially in hardware that feeds an audio signal of the first channel to a first output;   a subsystem, implemented at least partially in hardware that feeds an audio signal of the second channel to a second output;   wherein the first element of the audio signal and the second element of the audio signal are different elements within the audio signal.    
     
     
       19. The apparatus of claim 18, wherein the reducing subsystem employs digital controls.  
     
     
       20. The apparatus of claim 18, wherein the second output is at least one of a left output, right output, and surround output.  
     
     
       21. The apparatus of claim 18, wherein first output is a center channel output.  
     
     
       22. The apparatus of claim 18, wherein the first element of the audio signal is a trailer and the second element of the audio signal is a feature film.  
     
     
       23. The apparatus of claim 18, wherein the first element of the audio signal and the second element of the audio signal are in a Dolby Digital format.  
     
     
       24. The apparatus of claim 18, wherein the first element of the audio signal and the second element of the audio signal are digital streams.  
     
     
       25. The apparatus of claim 18, wherein the first element of the audio signal and the second element of the audio signal are multitrack digital soundtracks.  
     
     
       26. A non-transitory computer readable medium, storing software instructions for volume control of audio signals, which when executed by one or more processors cause performance of the steps of:
 reducing a setting of a volume control in response to a first element of an audio signal, the setting ranging from a minimum to a maximum,   in response to the reducing, adjusting a gain of a first channel of a second element of the audio signal and a gain of a second channel of the second element of the audio signal, for a range of volume control settings less than a first setting the adjusting both decreases loudness and increases a contribution of the first channel to the loudness of a reproduced second element of the audio signal, for a range of volume control settings less than a second setting the adjusting decreases the gain of the first channel in a substantially same manner as the gain of the second channel is decreased as the setting of the volume control is reduced;   feeding an audio signal of the first channel to a first output;   feeding an audio signal of the second channel to a second output;   wherein the first element of the audio signal and the second element of the audio signal are different elements within the audio signal.    
     
     
       27. The non-transitory computer readable medium of claim 26, wherein the reducing employs digital controls.  
     
     
       28. The non-transitory computer readable medium of claim 26, wherein the second output is at least one of a left output, right output, and surround output.  
     
     
       29. The non-transitory computer readable medium of claim 26, wherein first output is a center channel output.  
     
     
       30. The non-transitory computer readable medium of claim 26, wherein the first element of the audio signal is a trailer and the second element of the audio signal is a feature film.  
     
     
       31. The non-transitory computer readable medium of claim 26, wherein the first element of the audio signal and the second element of the audio signal are in a Dolby Digital format.  
     
     
       32. The non-transitory computer readable medium of claim 26, wherein the first element of the audio signal and the second element of the audio signal are digital streams.  
     
     
       33. The non-transitory computer readable medium of claim 26, wherein the first element of the audio signal and the second element of the audio signal are multitrack digital soundtracks.