[Freeswitch-users] MP2

[Thomas Auge]

After a bit of reading I cannot find anything codec specific about the unrestricted digital bearer capability type 
FreeTDM uses. There does seem to be a G722 type (7khz audio), but from their documentation that's not what FreeTDM does, 
and since G722 worked with such a hardware codec, it doesn't seem to be what they do either.

In an email Sangoma support once said: ... "we only support G.722 as an HD codec because it fits in the 64kbps stream 
(in fact any codec that fits 64kbps can be used with proper configuration)" ...

That sounds like only MP2 support in Freeswitch would be needed. Or am I missing something?


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.
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>> 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
>>>>
>>>
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