[Speex-dev] unsuccessful speex_echo_cancel() usage

julia rg juliarg at int.spb.ru
Mon Dec 4 03:05:17 PST 2006

Hello Jean-Marc and all,

I’ve got a problem with speex_echo_cancel usage. I only managed to get an
attenuation of 5-8 db using testecho.c and it depends heavily on the
playback/capture delay. I used clear speech as far-end input and same speech
with a bit of reverb, attenuation and delay as mic nput. I also tried using
played and recorded speech for mic input. I tried different constant delays and
got the following resuls. When the delay is 50 ms, the attenuation decreases
twice, and with a 100 ms delay there’s almost no echo cancellation.
Unfortunately, the application suggests the delay is up to 160 ms. I use a frame
size of 128 and a tail length of 1024, the sampling rate is 8000. I tried tail
lengths of 640, 2048 and 4096 with no significant effect. Also, the filter
output looks like the filter re-adapts after each pause in speech. I would be
very grateful for suggestions how to make this work properly.

Thanks in advance,

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