ARI Bridge always at 192 kHz, when all participants are 48 kHz

Hello,

When creating a Bridge using ARI, it looks like the bridge sampling frequency is locked to 192 kHz. There’s no argument on the ARI REST API call that I can see to specify it, or the context for the bridge.

Asterisk is being used on FreePBX.

ANCK-PC-MELE-01*CLI> core show channel PJSIP/1000-00000000
– General –
Name: PJSIP/1000-00000000
Type: PJSIP
UniqueID: 1719262327.4
LinkedID: 1719262326.0
Caller ID: 1000
Caller ID Name: test
Connected Line ID: 1234lemon
Connected Line ID Name: ABC
Eff. Connected Line ID: 123lemon
Eff. Connected Line ID Name: ABC
DNID Digits: (N/A)
Language: en_GB
State: Up (6)
NativeFormats: (opus)
WriteFormat: slin192
ReadFormat: slin192
WriteTranscode: Yes (slin@192000)->(slin@48000)->(opus@48000)
ReadTranscode: Yes (opus@48000)->(slin@48000)->(slin@192000)
Time to Hangup: 0
Elapsed Time: 0h0m35s
Bridge ID: c08799bb-bfdd-44ff-9c15-c0bdcd588891
– PBX –
Context: from-internal
Extension:
Priority: 1
Call Group: 0
Pickup Group: 0
Application: AppDial
Data: (Outgoing Line)
Call Identifer: [C-00000001]
Variables:
BRIDGEPEER=Local/1000@from-internal-00000000;2
GOSUB_RETVAL=
sipkey=
SIPHEADERKEYS=
TECH=PJSIP
DIALEDPEERNUMBER=1000/sip:1000@192.168.8.153:57016;transport=TCP;ob
KEEPCID=TRUE
CWIGNORE=
MON_FMT=wav
FROMEXTEN=unknown
TIMESTR=20240624-205207
YEAR=2024
MONTH=06
DAY=24
REC_STATUS=INITIALIZED
PICKUPMARK=1000
EXTTOCALL=1000
TTL=64
RINGTIMER=15
– Streams –
Name: audio-0
Type: audio
State: sendrecv
Group: -1
Formats: (opus)
Metadata:

Manually editing (just for testing) confbridge_additional.conf and restarting asterisk yielded no change in the bridge sampling frequency.

[general]
;This section reserved for future use
internal_sample_rate=48000

[default_user]
type = user
internal_sample_rate=48000

[default_bridge]
type = bridge
internal_sample_rate=48000

Local channels will be slin192 when originated by default unless you specify formats (or an originator channel) with the request, so that they can be more intelligent about what is in use.

Thanks that did the trick, you rock @jcolp !