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Diffstat (limited to 'UPGRADE.txt')
| -rw-r--r-- | UPGRADE.txt | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/UPGRADE.txt b/UPGRADE.txt index 84b3e8d5a..535782a86 100644 --- a/UPGRADE.txt +++ b/UPGRADE.txt @@ -208,6 +208,32 @@ chan_sip: progress indications into a 180 Ringing (if a 180 has not yet been transmitted) if 'progressinband=never'. + - The codec preference order in an SDP during an offer is slightly different + than previous releases. Prior to Asterisk 13, the preference order of + codecs used to be: + (1) Our preferred codec + (2) Our configured codecs + (3) Any non-audio joint codecs + + One of the ways the new media format architecture in Asterisk 13 improves + performance is by reference counting formats, such that they can be reused + in many places without additional allocation. To not require a large + amount of locking, an instance of a format is immutable by convention. + This works well except for formats with attributes. Since a media format + with an attribute is a different object than the same format without an + attribute, we have to carry over the formats with attributes from an + inbound offer so that the correct attributes are offered in an outgoing + INVITE request. This requires some subtle tweaks to the preference order + to ensure that the media format with attributes is offered to a remote + peer, as opposed to the same media format (but without attributes) that + may be stored in the peer object. + + All of this means that our offer offer list will now be: + (1) Our preferred codec + (2) Any joint codecs offered by the inbound offer + (3) All other codecs that are not the preferred codec and not a joint + codec offered by the inbound offer + CLI commands: - "core show settings" now lists the current console verbosity in addition to the root console verbosity. |