DesignAEC
Version 6 (Adrian Georgescu, 06/28/2009 05:50 pm)
| 1 | 2 | Adrian Georgescu | = Echo cancellation = |
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| 3 | 1 | Adrian Georgescu | [[TOC(Design*, depth=1)]] |
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| 5 | 1 | Adrian Georgescu | SIP SIMPLE client is a Python software library that allows for easy development of Internet communications end-points based on SIP and related protocols for voice, rich presence, session based instant messaging (IM), file transfers and desktop sharing. Other media types can be easily added by using an extensible high-level API. SIP SIMPLE client uses [http://www.pjsip.org/pjmedia/docs/html/index.htm PJSIP media library] for audio processing (sound card abstraction, audio codec and acoustic echo cancellation). |
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| 7 | 1 | Adrian Georgescu | For more information see http://sipsimpleclient.com |
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| 9 | 1 | Adrian Georgescu | == Background == |
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| 11 | 1 | Adrian Georgescu | The present implementation of the echo canceller from PJSIP media library is not performing to the desired level of quality. Practically, the speaker phone function of SIP SIMPLE client is not reliable and not performing satisfactory unless a headset is used. |
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| 13 | 1 | Adrian Georgescu | [[Image(http://www.pjsip.org/images/media-flow.jpg)]] |
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| 16 | 1 | Adrian Georgescu | == Project goal == |
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| 18 | 5 | Adrian Georgescu | Replace the existing AEC from Pjmedia library (what is displayed as echo.h in the above diagram) with a better solution to provide a high quality speakerphone user experience. |
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| 20 | 1 | Adrian Georgescu | The developed software will be released under an open source licence and distributed with SIP SIMPLE client library. |
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| 22 | 1 | Adrian Georgescu | == Resources == |
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| 24 | 1 | Adrian Georgescu | The following resources relates to open source AEC implementations: |
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| 26 | 1 | Adrian Georgescu | * PJSIP media library http://pjsip.org, used by this project, AEC is implemented based on the Speex library, the code in pjsip/pjmedia/src/pjmedia/echo_speex.c |
| 27 | 1 | Adrian Georgescu | * Media flow - http://trac.pjsip.org/repos/wiki/media-flow |
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| 29 | 6 | Adrian Georgescu | Speex AEC |
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| 31 | 1 | Adrian Georgescu | * Speex project http://speex.org, the echo canceller implements AEC based on the MDF algorithm, see speex/libspeex/mdf.c. A test client is available in speex/speexclient, this has been used for developing pjmedia equivalent |
| 32 | 1 | Adrian Georgescu | * http://speex.org/docs/api/speex-api-reference/group__SpeexEchoState.html |
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| 34 | 6 | Adrian Georgescu | Andree Adrian AEC |
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| 36 | 6 | Adrian Georgescu | * http://www.andreadrian.de/intercom/ implements AEC based on NLMS algorithm (not tested yet) |
| 37 | 1 | Adrian Georgescu | * Kphone AEC implemented using above AEC http://www.andreadrian.de/echo_cancel/ (not tested) |
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| 39 | 6 | Adrian Georgescu | General |
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| 41 | 6 | Adrian Georgescu | * Digital Signal Processing http://www.dsptutor.freeuk.com/ |
| 42 | 1 | Adrian Georgescu | * Graduation thesis about AEC http://innovexpo.itee.uq.edu.au/2003/exhibits/s365914/ |
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| 44 | 1 | Adrian Georgescu | == Job description == |
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| 46 | 1 | Adrian Georgescu | Project based, result oriented, works must be performed from remote. |