> For the complete documentation index, see [llms.txt](https://prosbcdocs.telcobridges.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://prosbcdocs.telcobridges.com/hidden-pages/support-srtp-encoding-and-decoding/modifying-media-relay-profile-settings/parameter-codecs-selection-mode.md).

# Parameter: Codecs selection mode

This controls which codecs are offered to call legs:

* All codecs: Keep all codecs in the SDPs, including those only known by one of the two legs. This may force a call to use transcoding if one of the call legs selects a codec unknown by the other.
* Compatible codecs only: Keep only codecs known by the two call legs. This ensures low-delay relay mode can be used. Fallback to transcoding mode will still occur if no compatible codecs exist between the two call legs.
* Active codec only: Keep only the active codec, which prevent any of the two legs to change codec later during the call.


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