[SR-Users] RTPengine - Transcoding example available?

[Muhammad Zaka]

Hi,

I am trying the following scenario: -
Caller (Side A) supports:
G722
PCMA
PCMU
G729

Callee (Side B) supports:
PCMA
PCMU
G729

I have configured like this:
rtpengine_offer("...codec-mask-opus codec-mask-G722 codec-mask-PCMA codec-mask-PCMU codec-mask-G729 transcode-PCMA transcode-PCMU transcode-G729")

But both sides end up on PCMA; where as I would like G722 for Caller side and PCMA for Callee's end and rtpengine should transcode between G722 to PCMA and vice versa.

Please can someone guide me.

Thanks

Regards
Muhammad Zaka

-----Original Message-----
From: sr-users [mailto:sr-users-bounces at lists.kamailio.org] On Behalf Of Richard Fuchs
Sent: 20 February 2018 19:01
To: sr-users at lists.kamailio.org
Subject: Re: [SR-Users] RTPengine - Transcoding example available?

On 2018-02-20 05:46 AM, Denys Pozniak wrote:
> Hello!
>
> Please explain how to achive next:
>
> Side A supports:
> OPUS
> PCMA
>
> Side B supports:
> OPUS
> PCMA
> PCMU
>
> I need to transcode in direction A->B from PCMA to OPUS?
> So should be like this:
> A(PCMA) -> (PCMA)Rtpengine(OPUS)->B(OPUS)
>
> I configured like this:
> rtpengine_offer("codec-mask-PCMA codec-transcode-opus"); 
> rtpengine_answer("codec-mask-opus codec-transcode-PCMA");
>
> But leg from Rtpengine to A has wrong codec (OPUS):
> https://drive.google.com/file/d/14GAIt8lL7Igj9S95b_RS6CXtmGVhjLa1/view
>

You don't need to put any transcoding options into rtpengine_answer() - they should all go into rtpengine_offer()

Since A supports all codecs that B supports except PCMU, you can add PCMU into the offer going to B with:

rtpengine_offer("... transcode-PCMU")

But most likely both sides will end up talking Opus (without
transcoding) since they both support it and it's listed first. If B ends up talking PCMU to rtpengine, it will transcode it to Opus as A doesn't support PCMA and Opus is first in its list. If either side ends up talking PCMA, it's also passed through without transcoding since both sides support it.

If you want to force PCMA on A's side and Opus on B's side, you need to:

1) accept PCMA from A, but don't offer it to B: codec-mask-PCMA
2) ignore that Opus was offered from A: codec-strip-opus
3) offer Opus to B: transcode-opus

Make sure you update your rtpengine code base as this use case has only just been implemented (previously the `transcode` option would simply negate the `codec-strip` which is not what you want). Full example:

rtpengine_offer("... ICE=remove codec-mask-PCMA codec-strip-opus
transcode-opus")

Cheers

_______________________________________________
Kamailio (SER) - Users Mailing List
sr-users at lists.kamailio.org
https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users