Hello
I need a little help with an application I am developing, it is a sip user agent, I have my own audio device implementation and I have used the auddemo application to verify that I can playback audio through my audio device
The next step was to use the simpleua sample, which works only with G711 codecs, however it is specified as 16 bits per sample, when it should be 8, at least that is what I've read everywhere else. The call is generated from an asterisk box, which I am positive is 8 bits per sample, so of course the audio is chopped up and distorted.
My audio device uses 16bit linear, so I thought I just had to receive the 8 bit samples and change the bit depth before delivering to the audio device, but apparently simpleua is expecting 16bit samples from the rtp data, is there a reason why this was implemented like this?
I looked in to the code, in pjmedia/src/pjmedia/g711.c
And it specifically sets the bit depth at 16 when the g711_default_attr function is called
static pj_status_t g711_default_attr (pjmedia_codec_factory *factory,
const pjmedia_codec_info *id,
pjmedia_codec_param *attr )
{
PJ_UNUSED_ARG(factory);
pj_bzero(attr, sizeof(pjmedia_codec_param));
attr->info.clock_rate = 8000;
attr->info.channel_cnt = 1;
attr->info.avg_bps = G711_BPS;
attr->info.max_bps = G711_BPS;
attr->info.pcm_bits_per_sample = 16; <---- is this what it is supposed to be??
......
It looks wrong to me because G711_BPS is defined as
#define G711_BPS 64000
And 16bits per sample x 8000 samples per second gives 128000
8 bits per sample x 8000 samples per second would give the correct value of 64000
And looking at other parts of the code, it seems the 16 bits per sample is hardcoded in other places as well. I might be misunderstanding the whole thing, and it is there for a reason. So if anyone could shed some light on the matter I would really appreciate it
Thank you
Jose
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From: pjsip [pjsip-bounces@xxxxxxxxxxxxxxx] on behalf of pjsip-request at lists.pjsip.org [pjsip-request at lists.pjsip.org]
Sent: Thursday, March 28, 2013 5:02 PM
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