How to record audio with pjsua

Follow this guide to record any audio coming into the conference bridge to a WAV file.

Run pjsua with additional --rec-file argument:
```
$ ./pjsua --rec-file OUTPUT.WAV
```
Note

Make sure pjsua quits properly before reading the WAV file, otherwise the WAV file may be detected as corrupt because the header does not contain the correct information.

See that the file has been registered to the conference bridge with cl command:

>>> cl
Conference ports:
Port #00[16KHz/10ms] Primary Sound Capture Driver  transmitting to:
Port #01[16KHz/10ms]           OUTPUT.WAV  transmitting to:

Make a call and establish media as usual.

When the call is established, normally it is “connected” to the sound device in the bridge. This can be confirmed with the cl command below:

>>> cl
Conference ports:
Port #00[16KHz/10ms] Primary Sound Capture Driver  transmitting to: #2
Port #01[16KHz/10ms]           OUTPUT.WAV  transmitting to:
Port #02[16KHz/20ms]   sip:user@localhost  transmitting to: #0

Now connect whatever port(s) to record to the OUTPUT.WAV port. For example, this command would record the audio from remote call to the WAV:
```
>>> cc 2 1
 09:40:08.969   conference.c Port 2 (sip:user@localhost) transmitting to port 1
(OUTPUT.WAV)
Success
```
You can also, for example, record the audio from the microphone to the WAV file at the same time:
```
>>> cc 0 1
 09:40:47.894   conference.c Port 0 (Primary Sound Capture Driver) transmitting
to port 1 (OUTPUT.WAV)
Success
```
In this case, the audio from both the call and the microphone will be first mixed in the conference bridge before it is recorded to the WAV file.
Now both the audio from the remote call and the audio from the microphone will be recorded to the WAV file, as can be seen with cl command:
```
>>> cl
Conference ports:
Port #00[16KHz/10ms] Primary Sound Capture Driver  transmitting to: #2 #1
Port #01[16KHz/10ms]           OUTPUT.WAV  transmitting to:
Port #02[16KHz/20ms]   sip:user@localhost  transmitting to: #0 #1
```
As can be seen from above output, both the sound device (port 0) and the call (port 2) are both transmitting to the WAV file, thus output from both will be mixed and recorded to the WAV file.
Note that when debugging audio problem, it’s probably best not to mix the audio from the problematic source with other sources so that we can be clear about the source of the problem.