[asterisk-dev] [Code Review] 4505: Asterisk 13 PJSIP sends RTP packets in wrong byte order on Intel platform when using slin codec

[Frankie Chin]

> On March 17, 2015, 4:57 p.m., Matt Jordan wrote:
> > /tags/13.2.0/res/res_rtp_asterisk.c, lines 3394-3406
> > <https://reviewboard.asterisk.org/r/4505/diff/1/?file=72594#file72594line3394>
> >
> >     I think your issue should be solved here.
> >     
> >     When you care a new smoother, you can specify whether or not it is BE or LE via the ast_smoother_set_flags call. The real issue is determining whether or not your machine is BE or LE.
> >     
> >     What distro/environment did you produce this issue on?

This issue was produced using Ubuntu 14.04.1 on Intel x86 platform. In Asterisk 12.8.1 I notice that when a smoother is created, the ast_smoother_set_flags() method is used to set the format flags into the smoother. Hence it is not deciding on BE/LE based on the machine platform.


> On March 17, 2015, 4:57 p.m., Matt Jordan wrote:
> > /tags/13.2.0/include/asterisk/codec.h, lines 77-80
> > <https://reviewboard.asterisk.org/r/4505/diff/1/?file=72588#file72588line77>
> >
> >     I don't think you can trust that the codec will know its endianness. Looking at the resample code, I don't _think_ it actually determines the endianness of its encoding/decoding, and instead relies on the underlying machine to make that determination. As such, I don't think this should be a property on the codec structure.

Matt, I actually followed the implementation in Asterisk 12.8.1 where the AST_SMOOTHER_FLAG_BE was defined for all the SLIN codecs in main/format.c under the format_list_init() method. Do you mean this implementation back in 12.8.1 was inappropriate? FYI, slin codec used to work fine in Asterisk 12.8.1 for our application.


- Frankie


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On March 17, 2015, 3:36 a.m., Frankie Chin wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/4505/
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> 
> (Updated March 17, 2015, 3:36 a.m.)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Bugs: ASTERISK-24858
>     https://issues.asterisk.org/jira/browse/ASTERISK-24858
> 
> 
> Repository: Asterisk
> 
> 
> Description
> -------
> 
> In Asterisk 13.2.0 when SLIN codec is used in two Asterisk servers registered to one another via PJSIP, the RTP payload is sent in the wrong byte order. The patch addresses the following based on the correct behavior in Asterisk 12.8.1:
> 1) Save ptime = 20 as the framing in the ast_rtp_codecs structure when creating outgoing SDP packet (res_pjsip_sdp_rtp.c)
> 2) Do not copy the framing when copying the payload (rtp_engine.c)
> 3) Introduce the new "smoother_be" flagin the ast_codec structure. Set this flag = 1 for all the SLIN codecs (codec_builtin.c).
> 4) Check for this "smoother_be" flag before using the smoother on the data (res_rtp_asterisk.c)
> 
> 
> Diffs
> -----
> 
>   /tags/13.2.0/res/res_rtp_asterisk.c 433002 
>   /tags/13.2.0/res/res_pjsip_sdp_rtp.c 433002 
>   /tags/13.2.0/main/rtp_engine.c 433002 
>   /tags/13.2.0/main/format.c 433002 
>   /tags/13.2.0/main/codec_builtin.c 433002 
>   /tags/13.2.0/include/asterisk/format.h 433002 
>   /tags/13.2.0/include/asterisk/codec.h 433002 
> 
> Diff: https://reviewboard.asterisk.org/r/4505/diff/
> 
> 
> Testing
> -------
> 
> The patch was tested using the scenario described in ASTERISK-24858
> 
> 
> Thanks,
> 
> Frankie Chin
> 
>

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