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How We Test Audio
Quality In VoIP
Applications
Rihards Skrebelis
Why it has to be tested?
What is VoIP?
What goes into VoIP application?
● Signaling
○ Establish call
○ Handover
○ Multiple person call
● Audio/Voice
○ Codec
○ Pe...
What has to be tested in VoIP application
● Signaling
○ Establish call
○ Handover
○ Multiple person call
● Audio/Voice
○ C...
Our focus
MOS and Delay under various network
conditions
MOS
● Started as manual evaluation
● Taken over by algorithm
● Requires reference and degraded file
● In our case we purch...
Delay
Simple end-to-end delay, between time when sound is sent and when
it is received on other device.
Methodology
We need to
● Control audio source
● Record audio source
● Record output audio
● Have recorded audio spend the ...
Audio hardware
Network conditioning
● Custom OS on network router
● Change parameters like
○ packet loss
○ bandwidth
○ jitter
○ delay
● A...
Making our work easier-
automating as much as we can
● Things we have to do
● Start a call
● Start audio playback
● Start ...
Things we can automate
● Start a call
● Start audio playback
● Start audio recording
● Split audio track
● Give audio to t...
./play $1 & ./rec $2 trim 0 9
sox $2 "$2_original.wav" remix 1
sox $2 "$2_degraded.wav" remix 2
sox "$2_original.wav" -b 1...
And we end up with this
More topics if we have time
● Jitter influence on quality and how it is handled
● The road to where we are now
● Improveme...
Questions?
How We Test Audio Quality In VoIP Applications by Rihards Skrebelis from TestDevLab at 68th Devclub.lv
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How We Test Audio Quality In VoIP Applications by Rihards Skrebelis from TestDevLab at 68th Devclub.lv

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Presentation will cover basics of VoIP and different challenges that we had to overcome to develop universal end-to-end solution for audio quality testing in VoIP applications.
(Language – Latvian)

Rihards started working as tester during studies in Riga Techincal University and got Bachelor Degree in 2014 with thesis focused around testing audio quality. Following years parallel to work as QA and test automation engineer co-developed process for evaluating voice call quality. More recently working on developing process for evaluation video call quality.

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How We Test Audio Quality In VoIP Applications by Rihards Skrebelis from TestDevLab at 68th Devclub.lv

  1. 1. How We Test Audio Quality In VoIP Applications Rihards Skrebelis
  2. 2. Why it has to be tested? What is VoIP?
  3. 3. What goes into VoIP application? ● Signaling ○ Establish call ○ Handover ○ Multiple person call ● Audio/Voice ○ Codec ○ Performance ○ Quality ○ Handling various quality internet ○ Handling internet interruptions ○ Echo cancelling ○ Background noise reduction ○ Loudness ○ etc.
  4. 4. What has to be tested in VoIP application ● Signaling ○ Establish call ○ Handover ○ Multiple person call ● Audio/Voice ○ Codec ○ Performance ○ Quality ○ Handling various quality internet ○ Handling internet interruptions ○ Echo cancelling ○ Background noise reduction ○ Loudness ○ etc.
  5. 5. Our focus MOS and Delay under various network conditions
  6. 6. MOS ● Started as manual evaluation ● Taken over by algorithm ● Requires reference and degraded file ● In our case we purchased licensed software
  7. 7. Delay Simple end-to-end delay, between time when sound is sent and when it is received on other device.
  8. 8. Methodology We need to ● Control audio source ● Record audio source ● Record output audio ● Have recorded audio spend the smallest possible time outside of devices ● Control volume for input and output ● Platform independent
  9. 9. Audio hardware
  10. 10. Network conditioning ● Custom OS on network router ● Change parameters like ○ packet loss ○ bandwidth ○ jitter ○ delay ● Accessible UI or SSH
  11. 11. Making our work easier- automating as much as we can ● Things we have to do ● Start a call ● Start audio playback ● Start audio recording ● End recording call and playback ● Split audio track ● Give audio to tool ● Gather results ● Change network conditions
  12. 12. Things we can automate ● Start a call ● Start audio playback ● Start audio recording ● Split audio track ● Give audio to tool ● Gather results ● Change network conditions
  13. 13. ./play $1 & ./rec $2 trim 0 9 sox $2 "$2_original.wav" remix 1 sox $2 "$2_degraded.wav" remix 2 sox "$2_original.wav" -b 16 "$2_original1.wav" sox "$2_degraded.wav" -b 16 "$2_degraded1.wav" echo "----- Remote server MOS evaluation -----" curl -X POST -H "Cache-Control: no-cache" -H "Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW" -F "1=@$2_original1.wav" -F "2=@$2_degraded1.wav" "http://10.1.5.58:8080/MOS/UploadServlet" rm "$2_original.wav" rm "$2_degraded.wav" rm $2
  14. 14. And we end up with this
  15. 15. More topics if we have time ● Jitter influence on quality and how it is handled ● The road to where we are now ● Improvements on the automation and scripts
  16. 16. Questions?

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