On Fri, Jul 3, 2009 at 11:38 AM, David Andrey <David.Andrey at netmodule.com>wrote:
> Hi Benny,
>
>
>
> Well, what I?m trying to do is as follow:
>
>
>
> 1.Get the audio port created by ?pjmedia_session_create()?
>
> status = pjmedia_session_get_port (mediaSession, 0, &mediaPort);
>
>
>
> 2. Open the sound device in full-duplex stereo (stereo is the only way at
> moment)
>
> pjmedia_aud_param audioParam;
>
> audioParam.dir = PJMEDIA_DIR_ENCODING_DECODING;
>
> audioParam.rec_id = -1; // auto select for audio device
>
> audioParam.play_id = -1;
>
> audioParam.clock_rate = mediaPort->info.clock_rate;
>
> audioParam.channel_count = 2; //mediaPort->info.channel_count;
>
> audioParam.samples_per_frame = 2* mediaPort->info.samples_per_frame;
>
> audioParam.bits_per_sample = mediaPort->info.bits_per_sample;
>
>
>
> PJ_LOG(3,(THIS_FILE, "create bidirectional audio ..."));
>
> status = pjmedia_snd_port_create2(inv->pool, &audioParam,
> &soundBidir);
>
>
>
> 3.Create a stereo-to-mono converter, which have the the G.711 audio port
> as downstream
>
> status = pjmedia_stereo_port_create(inv->pool,
>
> mediaPort,
>
> 2,
>
> 0,
>
> &stereoPort);
>
>
>
> 4. Connect the stereo port to the sound device
>
> status = pjmedia_snd_port_connect(soundBidir, stereoPort);
>
>
>
> All this is happening in the ?on_media_update()? callback.
>
>
So far so good actually. The above should work.
>
>
> So the data path I think to have is like this:
>
> In the capture direction (for 8kHz, 20 ms audio samples per frame):
>
> 1.sound device give a 320 samples / frame (2 channel, 160 samples/channel,
> 16 bit/sample)
>
> 2.stereo port convert this in 160 samples / frame (1 channel, 160 samples /
> channel, 16 bit/sample) and give it to the downstream port.
>
> 3.the G.711 encoder convert the pcm samples (1 channel, 160 samples, 8
> bit/sample) and send it to the network
>
>
>
> Has I could see, the G.711 encoder receives 160 samples / frames without
> the ?stereo-mono? conversion, but 80 by adding this one -> this observation
> started my changes in the stereo_port.
>
>
>
Something is not quite right there. With 20ms ptime, encoder should receive
160 samples after the frame is converted to mono, and not 80.
Can you check the contents of mediaPort->info? It should contain
clock_rate = 8000;
samples_per_frame = 160
channel_count = 1;
bytes_per_frame = 320;
If samples_per_frame is 80 (=10ms), that means you set
stream_info->param.setting.frm_per_pkt to 1 instead of 2. FYI the
G.711codec uses 10ms framing, hence in the codec param we usually set
frm_per_pkt
to 2 to make it 20ms ptime. So then something is not right with the sound
device, since it's asked to return 10ms stereo frames in the aud_param
(equalling 160 samples per frame) but yet it gives 320 samples in the
capture callback. What sound device abstraction are you using?
If all is proper then I probably need to check elsewhere.
cheers
Benny
Maybe I?m doing all this really wrong L But I?m sure there must be a way to
> solve my stereo ? mono problem in PJ J
>
>
>
> Thanks for helping.
>
>
>
> David
>
>
>
> *From:* pjsip-bounces at lists.pjsip.org [mailto:
> pjsip-bounces at lists.pjsip.org] *On Behalf Of *Benny Prijono
> *Sent:* Freitag, 3. Juli 2009 09:46
> *To:* pjsip list
> *Subject:* Re: [pjsip] G.711 with stereo hardware
>
>
>
> On Thu, Jul 2, 2009 at 2:46 PM, David Andrey <David.Andrey at netmodule.com>
> wrote:
>
> Maybe useful for someone J
>
>
>
> I made the following changes in stereo_port.c:
>
>
>
> *static* pj_status_t *stereo_get_frame*(pjmedia_port *this_port,
>
> pjmedia_frame *frame)
>
>
>
> //tmp_frame.*buf* = sport->get_buf? sport->get_buf : frame->*buf*;
> // allocate get buffer for stereo port ???
>
> //tmp_frame.size = sport->dn_port->info.bytes_per_frame;
>
> *if* (sport->get_buf)
>
> {
>
> tmp_frame.buf = sport->get_buf;
>
> tmp_frame.size = sport->dn_port->info.bytes_per_frame;
>
> }
>
> *else*
>
> {
>
> tmp_frame.buf = frame->buf;
>
> tmp_frame.size = frame->size; // *da*,
> 2009-06-30
>
> }
>
>
>
>
>
> *static* pj_status_t *stereo_put_frame*(pjmedia_port *this_port,
>
> *const* pjmedia_frame *frame)
>
>
>
> //tmp_frame.size = sport->dn_port->info.bytes_per_frame;
>
> tmp_frame.size = sport->dn_port->info.samples_per_frame // *da
> *, 2009-06-30
>
> * sport->base.info.bits_per_sample / 8;
>
>
>
> Still have memory problems (heap) in relation with the stereo usage. But
> stereo <-> G.711 seems ok now.
>
>
> Sorry I don't understand your patch above. When calling get_frame() or
> put_frame(), caller must supply frame size exactly as specified by
> port_info.bytes_per_frame of the specified port. I have a felling that
> somewhere your code does not do this hence the memory problem.
>
> Also the stereo port was not supposed to support G.711 channel conversion
> (i.e. only PCM), if this is what you're trying to do too.
>
> cheers
> Benny
>
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