Changes between Version 2 and Version 3 of MeasuringSoundLatency


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Timestamp:
Jul 28, 2008 11:24:45 AM (11 years ago)
Author:
bennylp
Comment:

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  • MeasuringSoundLatency

    v2 v3  
    88 * [http://www.pjsip.org/pjsua.htm pjsua] 
    99 * a computer with microphone and loudspeaker (not headset) 
    10  * [file:tock8.wav] WAV file attached. 
     10 * {{{tock8.wav}}} WAV file attached. 
    1111 * a WAV waveform display/analyzer to visually see the latency (such as Cool Edit on Windows) 
    12  * or {{{latency.c}}} file if you don't have WAV waveform analyzer program. This file is included in PJSIP version 0.9.5 and later in {{{pjsip-apps/src/samples}}} directory, or if you use older PJSIP you can find the [file:latency.c] file attached. 
     12 * or {{{latency.c}}} file if you don't have WAV waveform analyzer program. This file is included in PJSIP version 0.9.5 and later in {{{pjsip-apps/src/samples}}} directory, or if you use older PJSIP you can find the {{{latency.c}}} file attached. 
    1313 
    1414== Setup == 
     
    6262Here's what the recorded signal ({{{rec1.wav}}}) looks like in my WAV analyzer: 
    6363 
    64 [[Image(rec1.png)]] 
     64[[Image(rec1.PNG, 50%)]] 
    6565 
    6666The highlighted area in above picture shows one recording of both original signal and the echo. 
     
    6868If we zoom-in the highlighted area, it will look like this: 
    6969 
    70 [[Image(rec1-zoom.png)]] 
     70[[Image(rec1-zoom.PNG, 50%)]] 
    7171 
    7272And to find out the latency, just measure the interval between original signal and echoed signal: 
    7373 
    74 [[Image(rec1-latency.png)]] 
     74[[Image(rec1-latency.PNG, 50%)]] 
    7575 
    7676In this test, I found out that the latency is approximately 171 milliseconds.