[Freeswitch-dev] Recompile mod_opus for 8KHz sampling rate

Dimosthenis Arkoudeas dimosthenis at arkoudeas.com
Sun Jul 28 18:19:40 MSD 2013

Hi all,

Playing with mod_opus came up with the following.
I am trying to recompile the codec with 8Khz and 40ms ptime. I am not familiar with the codec internals and not really sure what parameters should I change...

In mod_opus.c :

Line 59:
int bitrate_bps = codec->implementation->bits_per_second;
                int use_vbr = 1;
                int complexity = 10;
                int use_inbandfec = 1;
                int use_dtx = 1;
                int bandwidth = OPUS_BANDWIDTH_FULLBAND;
                int err;

I suppose that the bandwidth must be changed to OPUS_BANDWIDTH_NARROWBAND and use_vbr=0 and I haven't found yet whether the FEC parameter is passed to opus encoder.

And in Line 184 , I think the following parameters must be changed

 switch_codec_interface_t *codec_interface;

        int samples = 480;

        int bytes = 960;

        int mss = 10000;

        int x = 0;

        int rate = 48000;

        int bits = 32000;

Can you propose any values about these parameters to achieve 8khz with 40ms packet time?

Thanks for any help,

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