[asterisk-bugs] [JIRA] (ASTERISK-29198) allow=audio, video, text: First codec must be an audio codec.

[Joshua C. Colp (JIRA)]

     [ https://issues.asterisk.org/jira/browse/ASTERISK-29198?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Joshua C. Colp updated ASTERISK-29198:
--------------------------------------

    Assignee: Alexander Traud  (was: Unassigned)
      Status: Waiting for Feedback  (was: Triage)

I think the least invasive option would be best for this. That means either documentation or sorting the codecs when configured. I do not think it is worth it to make changes throughout the tree to resolve this, and there is a chance of breaking things as a result just to resolve this.

The negative of sorting the codecs is that they no longer reflect the actual configuration, which may confuse individuals, so I lean more towards documentation.

> allow=audio,video,text: First codec must be an audio codec.
> -----------------------------------------------------------
>
>                 Key: ASTERISK-29198
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-29198
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Channels/chan_sip/CodecHandling, Core/General
>    Affects Versions: 16.15.0, 18.1.0
>            Reporter: Alexander Traud
>            Assignee: Alexander Traud
>            Severity: Minor
>              Labels: patch
>         Attachments: audio_not_first.patch, extensions.conf, sip.conf
>
>
> If the first codec in the list of allows is not an audio codec, not only the channel driver chan_sip but many more modules get crazy.
> *Steps to Reproduce*
> 1. configuration file {{sip.conf}} with {{allow=h264,ulaw}} in the \[general\] section
> 2. from one extension, dial another extension
> *Actual Results*
> {code}WARNING: channel.c: set_format: Unable to find a codec translation path: (h264) -> (ulaw)
> WARNING: channel.c: set_format: Unable to find a codec translation path: (ulaw) -> (h264){code}
> *Next Steps*
> A search with the Regular Expression {{ast_format_cap_get_format\(.+, 0\);}} revealed many channels and modules seem affected like {{app_mp3}}, {{core_unreal}}, and {{res_speech}}. However, I did not test those. Even {{chan_sip}} has one more place in source code, which looks affected: When the ptime / framing is negotiated.
> The attached patch fixes just the reported scenario, the bug in {{main/channel.c}}. There, the code assumes audio codecs only anyway; therefore I added a filter. After fixing that, I had to fix another bug in {{channels/chan_sip.c}} to get the scenario above working. I did not analyze/understand all other occurrences. Therefore, it might be better to
> a) place a note in the documentation rather than fixing this, or
> b) sort the codecs while importing the configuration,
> c) go through the _whole_ code and revise this.
> In any case, I am not sure if it helps anyone if I patch just the reported issue. From my point of view, that would not solve but hide the problem just deeper. What do you think?
> *Workaround*
> The first allowed codec must be an audio codec. Therefore it is best when you go for {{allow=audio,video,text}}.



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