Would someone mind pointing me in the right direction for capturing audio to
a buffer?  I have multiple inbound calls and I would like to check for
in-band DTMF (no rfc2833). What is the API order for setting up PJSIP to get
the audio data?  I just need some framework help -- I have reviewed the
sample files on the web site but I'm having trouble grasping which APIs to
use. I do know how to do play audio files, it's the capturing to a buffer
that has me confused.  I mostly use the PJSUA APIs.

Global

pjsua_pool_create

[Shared pool used for all calls]

Call comes in (for each call do below)

pjmedia_mem_capture_create

[What size buffer should I use? Does it matter?]

[How do I get the call information such clockrate, etc, so I can set this
API to use the same values as the call?  Does it matter? Or should I use the
values in the sample programs?]

pjmedia_mem_capture_set_eof_cb

[How do I connect the call to this media port for so the media port is
"listening" and the callback works]

Call ends

pjmedia_port_destroy

Thank you in advance,

Archie

David,

Thank you for the information!  I appreciate the help.

Take care,

Archie

From: pjsip-bounces@lists.pjsip.org [mailto:pjsip-bounces@lists.pjsip.org]
On Behalf Of David Clark
Sent: Thursday, September 17, 2009 9:43 PM
To: pjsip list; 'pjsip list'
Subject: Re: [pjsip] Capture Call Audio to Buffer

At 10:37 AM 9/15/2009, Archie Rosenblum wrote:

Content-Type: multipart/alternative;
boundary="----=_NextPart_000_0088_01CA35F8.E071DB00"
Content-Language: en-us

Would someone mind pointing me in the right direction for capturing audio to
a buffer?  I have multiple inbound calls and I would like to check for
in-band DTMF (no rfc2833). What is the API order for setting up PJSIP to get
the audio data?  I just need some framework help -- I have reviewed the
sample files on the web site but I'm having trouble grasping which APIs to
use. I do know how to do play audio files, it's the capturing to a buffer
that has me confused.  I mostly use the PJSUA APIs.

Global

pjsua_pool_create
[Shared pool used for all calls]

Call comes in (for each call do below)

pjmedia_mem_capture_create
[What size buffer should I use? Does it matter?]

For FFT analysis I used a buffer size of 2000 bytes.  The idea being the
bigger the buffer size the more accurate the result.  The smaller the buffer
the more real time
the data result.

[How do I get the call information such clockrate, etc, so I can set this
API to use the same values as the call?  Does it matter? Or should I use the
values in the sample programs?]

Yes I think it matters.  I use the pjsua_conf_get_port_info() function to
get this data then pass it along.  It looks something like this:
pjsua_conf_get_port_info(sip_data[line].conf_slot, &info);
sip_data[line].cpa_clock_rate=info.clock_rate;
pjmedia_mem_capture_create(sip_data[line].cpa_pool,
sip_data[line].cpa_int_data, CPA_FFT_SIZE,
info.clock_rate, info.channel_count,
info.samples_per_frame, info.bits_per_sample, 0, &sip_data[line].cpa_port);

pjmedia_mem_capture_set_eof_cb

[How do I connect the call to this media port for so the media port is
"listening" and the callback works]

// line_number is supplied by the application to sort out multiple line
implmentation.
pjmedia_mem_capture_set_eof_cb(sip_data[line].cpa_port,
&sip_data[line].line_number, cpa_fft_got_data);

// add the memory capture port to the bridge
pjsua_conf_add_port(sip_data[line].cpa_pool, sip_data[line].cpa_port,
&sip_data[line].cpa_conf_port);

// then connect the conf_slot for the call and the cpa_conf_slot.
pjsua_conf_connect(sip_data[line].conf_slot, sip_data[line].cpa_conf_port);

The callback function will look like this:
pj_status_t cpa_fft_got_data(pjmedia_port *port, void *usr_data)
{

usr_data will contain the line_number passed int.
Then I think you call pjmedia_port_get_frame(port, frame);
and frame->buf I think has your audio data.

Yea I didn't realize until I typed out this message, my code was missing
that piece.  So
helping you helped me.
}

Call ends

pjmedia_port_destroy

Thank you in advance,
Archie

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