[Speex-dev] Writting a line in encoder with speex compression.

Juan Zapatero jazc at gmvsistemas.es
Wed Jan 4 04:12:03 PST 2006

first of all, I am going to sum up what I am trying to do, so that best
advice can be given. The final objective is to write a simple
application to establish a VoIP communication over a GPRS link. So it
would be to get a full duplex (capture/playback) sound application that
captured from microphone, compresses speech with Speex, and sends it
trough the socket API over the GPRS link.
By now, I am trying to get the audio part to work. I wrote a simplest
capture-playback program, based on the ALSA api, optimized to capture
speech (mono, 8000Hz, 16bits little-endian). Once wrote, I tested
capturing into a raw file, and then compressing the file with speexenc.
So far everything was a succeed.
Then, I tried introducing the compression into the audio program
following the indications given in Speex Codec Manual (both into de API
section and mostly in the sampleenc code:
- The resulting program works, but the quality is much poorer than using
speexenc over a raw file (much noisier).
- The ALSA PCM api, uses a capture buffer of 340bytes, but speex encoder
expects a 160bytes buffer, I think here could be the problem, as I am
trying to force speex_encoder to use a 340bytes buffer.

Any help would be grateful.
Juan Zapatero.

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Gracias por su colaboracion.
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