Changes between Version 1 and Version 2 of MeasuringSoundLatency


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Timestamp:
Jul 28, 2008 11:20:19 AM (11 years ago)
Author:
bennylp
Comment:

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  • MeasuringSoundLatency

    v1 v2  
    88 * [http://www.pjsip.org/pjsua.htm pjsua] 
    99 * a computer with microphone and loudspeaker (not headset) 
    10  * {{{tock8.wav}}} WAV file (see the attachment on the bottom of this page) 
     10 * [file: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 (see the attachment on the bottom of this page) if you don't have WAV waveform analyzer program. 
     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. 
    1313 
    1414== Setup == 
     
    6262Here's what the recorded signal ({{{rec1.wav}}}) looks like in my WAV analyzer: 
    6363 
     64[[Image(rec1.png)]] 
    6465 
    6566The highlighted area in above picture shows one recording of both original signal and the echo. 
     
    6768If we zoom-in the highlighted area, it will look like this: 
    6869 
     70[[Image(rec1-zoom.png)]] 
     71 
    6972And to find out the latency, just measure the interval between original signal and echoed signal: 
     73 
     74[[Image(rec1-latency.png)]] 
    7075 
    7176In this test, I found out that the latency is approximately 171 milliseconds.