[asterisk-bugs] [JIRA] (ASTERISK-26611) res_rtp_asterisk: Fix byte order on non-8kHz signed linear

[Joshua Colp (JIRA)]

     [ https://issues.asterisk.org/jira/browse/ASTERISK-26611?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Joshua Colp updated ASTERISK-26611:
-----------------------------------

    Summary: res_rtp_asterisk: Fix byte order on non-8kHz signed linear  (was: L16/16000 codec send little endian data with chan_sip on x86)

> res_rtp_asterisk: Fix byte order on non-8kHz signed linear
> ----------------------------------------------------------
>
>                 Key: ASTERISK-26611
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-26611
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Core/RTP
>    Affects Versions: 13.7.0
>         Environment: Ubuntu 14.04.5  on i686 
>            Reporter: Vitaly K
>            Assignee: Unassigned
>            Severity: Minor
>         Attachments: L16_sending_little_endian_bugfix.patch
>
>
> I try use L16/16000 codec enabled by allow=slin16 in sip.conf of asterisk-13.7.0 on x86 arch with communication with softphone on top of pj-project.
> When play test wav file peer side heard noise instead of music.
> With other codec selected - music heard as expected.
> I run tests with MixMonitor on asterisk - record is music not noise.
> I convert wav file to raw sln16 and convert it to big-endian (because asterisk can't read big-endian wav files aka RIFX)
> In this case peer heard  music not noise!
> I run tcpdump for catch rtp stream and manually examine raw rtp data and raw sln16 (but big-endian) file.  
> Byte order in this sources is same!
> I make some review for asterisk source code and found: 
> a) asterisk allow to read only little-endian wav files aka RIFF
> b) when this type of file readed always convert to native machine byte order and define this format as slin16
> c) when select codec is L16 same format used and no convertion of byte order before send rtp 
> d) on little-endian machines this cause outgoing stream placed in little-endian byte order
> It breaks of RFC what define L16 have big-endian byte order.



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