System Recording Audio Formats

I was looking at system recordings and wondering if I am causing unnecessary processor usage by having to convert audio files on the fly or storing completely useless audio files.

There are the options of: alaw g722 gsm sln sln16 sln48 ulaw wav

Right now we are using wav, gsm, sln, sln16, and ulaw normally. Does anything even load the sln file types? I know wav is used on the UCP and as a raw. Ulaw is the default audio format in the USA. GSM is for compatability. Should recordings have a G722 version when inbound calls seem to universally be ULAW?

I do not try that, but it may cause transcoding which effects the system performance.

Thats what I am wondering. Which system recording audio types actually matter and which can be left off to save space for the others. We might have some transcoding happening so I wanted to figure out what I should enable/disable before going through all of them.

I am noticing SLN only seems to be used at:

[2018-06-15 10:57:25] VERBOSE[5774][C-00003af8] app.c: x=0, open writing:  /var/spool/asterisk/confbridge/confbridge-name-9859-1529074625.66480 format: sln, 0x7fb31800ed20
[2018-06-15 10:58:37] VERBOSE[7305][C-00003b0e] app.c: x=0, open writing:  /var/spool/asterisk/confbridge/confbridge-name-9859-1529074699.66574 format: sln, 0x7fb0c4002da0
[2018-06-15 10:59:48] VERBOSE[9034][C-00003b24] app.c: x=0, open writing:  /var/spool/asterisk/confbridge/confbridge-name-9859-1529074778.66720 format: sln, 0x7faf980fc3f0
[2018-06-15 11:00:10] VERBOSE[9506][C-00003b2c] app.c: x=0, open writing:  /var/spool/asterisk/confbridge/confbridge-name-9859-1529074796.66766 format: sln, 0x7fb0c0018750
[2018-06-15 11:42:12] VERBOSE[31783][C-00003d93] pbx.c: Executing [[email protected]:3] ExecIf("PJSIP/1361-00001b34", "0?System(rm .sln)") in new stack
[2018-06-15 11:48:03] VERBOSE[7129][C-00003df1] pbx.c: Executing [[email protected]:3] ExecIf("PJSIP/1361-00001b7d", "0?System(rm .sln)") in new stack
[2018-06-15 13:53:56] VERBOSE[18451][C-00004486] pbx.c: Executing [[email protected]:3] ExecIf("PJSIP/1361-00001f33", "0?System(rm .sln)") in new stack

As far as I can tell so it almost looks like SLN isn’t being used by any recordings.