How to Avoid SLIN16 transcoding in Asterisk 1.8?

Dear all,

I’m trying to create a MusicOnHold group in Asterisk 1.8 where all of its members use SLIN16 codec.

I don’t know why, the MOH group works, but in Asterisk, when I check the channel (core show channel XXXXXXX) I realize that asterisk is doing transcoding (slin --> G722 --> slin16) either in read and write operations.

How can I avoid this?


Francesc Mestre

Provide MoH files that are already in SLIN16 format. One of the CLI commands will tell you the file extensions for the various codecs.

Thank you very much David!,

but the escenario is not too easy. Sorry for the confusion, but I forgot to specify the full scenario:

  • I’ve created a paging group (is not a MOH group).
  • The music source is not a file.
  • The music source is a SIP device that plays music to the others devices into the paging group.
  • Either source device and destination devices are only using SLIN16 codec but Asterisk seems still transcoding media streaming.

I’m not able to force Asterisk to not transcoding and permit slin16 stream go through it.
Kind regards!,


app_page, in Asterisk 1.8, involves the use of app_meetme. MeetMe is a conference bridging application and only operates at 8kHz.

Thank you very much Malcolmd!,

it’s clear what you say. So there is an alternative app to meetme that permits operate in 16kHz?

Best regards,

Francesc Mestre


Though there’s a version of app_confbridge, that can be compiled with 16kHz support (by editing the file and uncommenting that support) in Asterisk 1.8, it’s not a full-featured conferencing application. That didn’t happen for app_confbridge until Asterisk 10, when app_confbridge was completely rewritten.

See the Asterisk wiki - for info on app_confbridge


Thank you very much Malcolmd,

I’ve seen that in Asterisk 11 not only app_confbrige was already rewritten (since Asterisk 10) also app_page was rewritten to use Confbridge instead Meetme. This is what I need.

Thank you very much guys!,

Francesc Mestre

Correct, yes, app_page in Asterisk 11 uses Confbridge as the underlying technology instead of MeetMe.