Method and apparatus for active latency characterization

Abstract

Briefly, in accordance with one embodiment of the invention, a method for actively characterizing the latency of an audio channel of a computer, such as a personal computer, is provided. At least two signal streams for a waveform are created in the audio channel. The presence of the first signal sample stream for the waveform and the second signal sample stream for the waveform is detected at a point in the audio channel. The time between the detections of the signal sample streams is measured. Briefly, in accordance with another embodiment of the invention, a method of actively characterizing the latency of an audio channel of a computer, such as a personal computer, is provided. At least a first and a second waveform are created in the audio channel. The presence of the first and the second waveform are detected at a point in the audio channel. The time between the detections of the waveforms is measured.

What is claimed is:  
     
         1 . A method for actively characterizing the latency of an audio channel of a computer, comprising: 
 creating at least two signal streams for a waveform in said audio channel;    detecting the presence of the first signal sample stream for said waveform and the second signal sample stream for said waveform at a point in said audio channel; and    measuring the time between the detections of the signal sample streams.    
     
     
         2 . The method of  claim 1 , wherein said audio channel includes an audio signal output device and an audio signal input device; 
 creating a waveform in said audio channel comprising creating a waveform in said audio channel before said audio signal output device, said waveform having a signature to activate said audio signal output device to produce an audio output signal; and    detecting the presence of a first signal sample stream for said waveform and a second signal sample stream for said waveform at a point in said audio channel comprising detecting the signal sample streams in said audio channel at a point after said audio signal input device, wherein the first signal sample steam was propagated along a reference channel path in said computer and the second signal steam was produced from said audio output signal and propagated along a local channel path in said computer.    
     
     
         3 . The method of  claim 2 , wherein the audio signal output device includes at least one speaker.  
     
     
         4 . The method of  claim 2 , wherein the audio signal input device includes a microphone.  
     
     
         5 . The method of  claim 2 , wherein said waveform comprises a chirp waveform.  
     
     
         6 . The method of  claim 2 , wherein said waveform comprises a pseudo-random sequence waveform.  
     
     
         7 . The method of  claim 2 , wherein said waveform comprises a sine waveform.  
     
     
         8 . The method of  claim 2 , wherein measuring the time between the detections comprises counting the number of signal samples between the detections.  
     
     
         9 . The method of  claim 1 , wherein after creation, the two signal streams propagate along two different paths in said computer.  
     
     
         10 . The method of  claim 1 , wherein said computer comprises a personal computer.  
     
     
         11 . The method of  claim 1 , and further comprising: delaying at least one of the signal sample streams based, at least in part, on the time measured between the detections.  
     
     
         12 . A method for actively characterizing the latency of an audio channel of a computer comprising: 
 creating at least a first and a second waveform in said audio channel;    detecting the presence of the first and second waveform at a point in said audio channel; and    measuring the time between the detections of the waveforms.    
     
     
         13 . The method of  claim 12 , wherein at least one of said waveforms comprises a chirp waveform.  
     
     
         14 . The method of  claim 12 , wherein at least one of said waveforms comprises a pseudo-random sequence waveform.  
     
     
         15 . The method of  claim 12 , wherein at least one of said waveforms comprises a pseudo-random sequence waveform.  
     
     
         16 . The method of  claim 12 , wherein after creation, the two waveforms propagate along two different paths in said computer.  
     
     
         17 . The method of  claim 12 , wherein said computer comprises a personal computer.  
     
     
         18 . The method of  claim 12 , and further comprising: delaying at least one of the waveforms, based at least in part, on the time measured between the detections.  
     
     
         19 . An article comprising: 
 a machine-readable storage medium, said storage medium having stored thereon instructions, said instructions, when executed by a computer system including an audio channel, resulting in the following steps: 
 creating at least two signal streams for a waveform in said audio channel;  
 detecting the presence of the first and the second signal sample stream for said waveform at a point in said audio channel; and  
 measuring the time between the detections of the signal sample streams.  
   
     
     
         20 . The article of  claim 19 , wherein the waveform comprises a chirp waveform.  
     
     
         21 . The article of  claim 19 , wherein the computer system including an audio channel comprises a personal computer system including an audio channel.  
     
     
         22 . An article comprising; 
 a machine-readable storage medium, said storage medium having stored thereon instructions, said instructions, when executed by a computer system including an audio channel, resulting in the following steps: 
 creating at least two signal waveforms in said audio channel;  
 detecting the presence of the first and the second waveforms at a point in said audio channel; and  
 measuring the time between the detections of the waveforms.  
   
     
     
         23 . The article of  claim 22 , wherein at lease one of the waveforms comprises a chirp waveform.  
     
     
         24 . The article of  claim 22 , wherein the computer system including an audio channel comprises a personal computer system including an audio channel.