[Speex-dev] 4kbps sounds robotic on TMS320C64

Andy Ngo ndno72-speex at yahoo.com
Wed Dec 12 14:47:50 PST 2007


I'm currently working on the TI DaVinci processor, which has an ARM926 processor and a TMS320C64+ DSP in it.  I have been using Speex 6kbps (narrowband, quality=2, complexity=1, perceptual_enh=0) on the DSP C64+ side without any issues; the voice sounds very good for such a low bandwidth requirement.  However, recently, I tried out the 4kbps mode (changing quality to 1) on the DSP and it sounds robotic; if I ported the same 4kbps code to use on the ARM926 (GPP) side of the DaVinci, it sounds fine (no robotic artifacts).  So this leads me to think somehow the Speex code is not working properly for 4kbps (and lower) on the DSP C64+ processor side (6kbps sounds good as mentioned above).  I followed the ti speex_C64_test trunk example packaged with the Speex code; I used the example config.h and Makefile for my build.  Am I doing something wrong with the compilation of the Speex code for the DSP C64+?  I tried changing the complexity to 10 and turning on
 perceptual enhancement and it still sounds robotic; again, like I mentioned above, the ARM side sounds fine with the 4kbps mode.  Please advise.  Thanks.

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