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Revision as of 23:58, 24 July 2016 by DOS386 (talk | contribs) (resampler is maybe useful)

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The Speex codec is deprecated! Xiph recommends you use the superior Opus codec instead.


The Speex homepage has all the project info.

There is also a Speex FAQ.


See Speex hardware for a partial list of supported hardware


While the codec is deprecated, its source code package contains still useful resampling code used by some other audio projects.


These are some improvements that could be made to Speex.

Let us know if you'd like to work on one of them.

  • Speech/signal processing (DSP design)
    • Improve noise suppression (get rid of musical noise) and residual echo suppression
    • Improve packet-loss concealment (PLC)
    • Re-write the built-in voice activity detector (VAD)
    • Improve the 2.15 kbps vocoder mode (there are even 4 unused bits left to use)
    • Algorithmic optimizations (see if some searches can be simplified/approximated)
  • Complete fixed-point (DSP development)
    • Wideband
    • VBR
    • Rest of the narrowband modes
    • Preprocessor (noise suppression, AGC)
    • Jitter buffer
    • Arch-specific optimization
    • More...
  • Tune (playing with parameters)
    • Noise weighting filter
    • Perceptual enhancement
  • Features (plain C programming)
    • Implement maximum VBR bit-rate
    • Implement peeling (write functions to strip some of the bits)
      • Peel high-band (wideband -> narrowband)
      • Transform 24.6 kbps mode to 15 kbps mode
  • Documentation
    • Use questions from the mailing list to create a better FAQ on this wiki
    • Update the Speex manual based on recent papers
    • Improve libspeex documentation
    • Write good example code

External links