[Freeswitch-users] MP2

[Thomas Auge]

I'm trying to find some detailed specs on this, but so far no luck. There is quite an array of products of that kind out 
there. They must have set this up other than with trial and error ...

One interesting thing about them is that interoperability depends on selecting the correct codec on both ends, so there 
doesn't seem to be an SDP type negotiation going on. It really seems as if these codecs are just slapped on top of a 
digital connection without any extra magic.


On 05.01.2015 17:52, Michael Jerris wrote:
> Likely, you wont get full call setup, but you could see the inital setup message.  Alternatively, there is a way that
> you can setup some cards passive and you can tap and listen, depends on the hardware.
>
>> On Jan 5, 2015, at 1:49 PM, Thomas Auge <auge at virtues.net> wrote:
>>
>> These are hardware boxes. Can I capture the data with another ISDN card on the same BRI?
>>
>>
>> On 05.01.2015 15:38, Michael Jerris wrote:
>>> For any hope to achieve this we are going to needs some more info... preferably in the way of specifications.
>>> It's maybe possible if you can capture the isdn traffic from working equipment using this that you could decode
>>> it (Wireshark does a decent job of this) and see what exactly its signaling.
>>>
>>>
>>>
>>>
>>>> On Jan 5, 2015, at 1:34 PM, Thomas Auge <auge at virtues.net> wrote:
>>>>
>>>>> To understand this a little better.  Is MP2 over data channel a standard that needs to be interoperated with?
>>>>> Is there details how this is signalled to the other side or are both sides just configured to support it?
>>>>
>>>> Unfortunately I don't know. I didn't know there were multiple approaches to this. The currently implemented
>>>> G722 method works with these boxes, so the assumption was it's all the same with other codecs. If a data
>>>> channel is not a common method to achieve this, then it's most likely not what they are doing.
>>>>
>>>>
>>>>>> On Jan 5, 2015, at 1:06 PM, Michael Jerris <mike at jerris.com <mailto:mike at jerris.com>> wrote:
>>>>>>
>>>>>> When g722 is used over isdn, it is a voice channel marked as g722, NOT a data channel with voice codec
>>>>>> data.
>>>>>>
>>>>>>> On Jan 2, 2015, at 5:20 PM, Thomas Auge <auge at virtues.net <mailto:auge at virtues.net>> wrote:
>>>>>>>
>>>>>>> There are ISDN devices which establish a digital (data) ISDN connection and then use all kinds of codecs
>>>>>>> on top of that. Think FreeTDM with G722 - same thing. As far as I know FreeTDM doesn't care which codec
>>>>>>> you choose for a digital connection. G722 is just the most common use case.
>>>>>>>
>>>>>>> MP2 is still a widely used standard in broadcast, i.e. for remote contributions.
>>>>>>>
>>>>>>> On 02.01.2015 19:08, Brian West wrote:
>>>>>>>> I'm still puzzled as to why mp2, since ISDN is native PCM (ulaw/alaw), Do you have some legacy files
>>>>>>>> or systems you're working with that require this?  Trying to fully understand your thought process and
>>>>>>>> needs.
>>>>>>>>
>>>>>>>> On Fri, Jan 2, 2015 at 4:04 PM, Thomas Auge <auge at virtues.net
>>>>>>>> <mailto:auge at virtues.net><mailto:auge at virtues.net>> wrote:
>>>>>>>>
>>>>>>>> Digital ISDN calls, so I think as far as freeswitch is concerned, voice calls, yes.
>>>>>>>>
>>>>>>>>
>>>>>>>> On 02.01.2015 18:52, Brian West wrote:
>>>>>>>>> In what context?  playing sound files, voice calls what?
>>>>>>>>>
>>>>>>>>> On Fri, Jan 2, 2015 at 3:49 PM, Thomas Auge <auge at virtues.net
>>>>>>>>> <mailto:auge at virtues.net><mailto:auge at virtues.net>
>>>>>>>>> <mailto:auge at virtues.net<mailto:auge at virtues.net>>> wrote:
>>>>>>>>>
>>>>>>>>> Hello list,
>>>>>>>>>
>>>>>>>>> would it be a big task to add mp2 (transcoding) to freeswitch? What would be a realistic bounty for
>>>>>>>>> it?
>>>>>>>>>
>>>>>>>>> Cheers!
>>>>>>>>>
>>>>>>>>> Thomas
>>>>>>
>>>>>
>>>
>>>
>>> _________________________________________________________________________ Professional FreeSWITCH Consulting
>>> Services: consulting at freeswitch.org http://www.freeswitchsolutions.com
>>>
>>> Official FreeSWITCH Sites http://www.freeswitch.org http://confluence.freeswitch.org http://www.cluecon.com
>>>
>>> FreeSWITCH-users mailing list FreeSWITCH-users at lists.freeswitch.org
>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users http://www.freeswitch.org
>>>
>>
>>
>> _________________________________________________________________________ Professional FreeSWITCH Consulting
>> Services: consulting at freeswitch.org http://www.freeswitchsolutions.com
>>
>> Official FreeSWITCH Sites http://www.freeswitch.org http://confluence.freeswitch.org http://www.cluecon.com
>>
>> FreeSWITCH-users mailing list FreeSWITCH-users at lists.freeswitch.org
>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users http://www.freeswitch.org
>
>
> _________________________________________________________________________ Professional FreeSWITCH Consulting
> Services: consulting at freeswitch.org http://www.freeswitchsolutions.com
>
> Official FreeSWITCH Sites http://www.freeswitch.org http://confluence.freeswitch.org http://www.cluecon.com
>
> FreeSWITCH-users mailing list FreeSWITCH-users at lists.freeswitch.org
> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users http://www.freeswitch.org
>