[asterisk-dev] [Regression issue] Garbage RTP data with Asterisk

[Hans Petter Selasky]

On 02/26/15 15:19, Hans Petter Selasky wrote:
> On 02/08/15 11:24, Hans Petter Selasky wrote:
>> On 02/08/15 08:45, Hans Petter Selasky wrote:
>>> On 02/08/15 08:44, Hans Petter Selasky wrote:
>>>> Hi,
>>>>
>>>>  From time to time the Asterisk RTP engine outputs some 4-byte ULAW
>>>> packets (even when the data stream is ALAW), making me believe that the
>>>> packets don't come from the source channel driver. The content of the
>>>> packets is constant: 0x02 0x8A 0x02 0x80
>>>>
>>>> These cause pops/clicks at the receiver. How can the source of these
>>>> packets be found? Is there perhaps a race in Asterisk?
>>>>
>>>> Has anyone seen this issue before. I have a very old installation of
>>>> Asterisk ~v1.6 which does not exhibit this issue.
>>>>
>>>> --HPS
>>>>
>>>
>>> Forgot to mention:
>>>
>>> Seen with Asterisk 1.8 and 11
>>>
>>> --HPS
>>>
>>>
>>
>> Hi,
>>
>> Some further investigation reveals that the payload type is "0" instead
>> of "101" for DTMF.
>>
>> The 4 bytes are a DMTF packet and apparently this function has failed:
>>
>>>         /* Grab the payload that they expect the RFC2833 packet to be
>>> received in */
>>>         payload =
>>> ast_rtp_codecs_payload_code(ast_rtp_instance_get_codecs(instance), 0,
>>> AST_RTP_DTMF);
>>
>> --HPS
>>
>
> Hi Matthew,
>
> Sorry for late reply, there was a problem with my list subscription.
>
>  > What is the DTMF payload code negotiated by both sides?
>
> How can I find this out using the asterisk cli?
>
> --HPS

What I know is that uLAW and aLAW is used for the audio, and these 
invalid DTMFs cause regular pops and clicks in the audio stream.

--HPS