[Freeswitch-users] MP2

[Thomas Auge]

A very interesting tech demo, but from his own readme, it might not be suitable for a freeswitch module:

  - imprecise: due to the integer-only implementation, many rounding errors will
    occur; expect a 45-55 dB noise margin!
  - slow: it implements the synthesis process from the spec, which is very slow
    (82 multiplications, 1-2 divisions and countless shifts and additions per
    sample!)
  - not robust: it may easily crash on broken input data. Also, it ignores CRC
    values completely.
  - not thread-safe

A bit of a bummer, because a lightweight decoder on top of twolame would have been nice.


On 03.01.2015 13:51, Steve Underwood wrote:
> I have no idea how well it works, but there is this MP2 decoder -
> http://keyj.emphy.de/kjmp2/
>
> On 01/03/2015 07:00 AM, Brian West wrote:
>> That looks like just the encoder, so we would need both the encoder
>> and decoder that takes signed linear.  I'll be on the look out for an
>> option too.
>>
>> On Fri, Jan 2, 2015 at 4:54 PM, Thomas Auge <auge at virtues.net
>> <mailto:auge at virtues.net>> wrote:
>>
>>      > G722 can be a native bearer capability on an ISDN b-channel but thats not widely used.  MP2 in your case is just
>>      > establishing a data channel be it via ISDN or IP.
>>
>>      Yup. I'm fairly certain that's what FreeTDM does for G722, else it
>>      wouldn't make much sense to have a codec
>>      configuration option. :)
>>
>>
>>      > Before proceeding I would seek out a license compatible
>>      encoder/decoder library that can be used, MP2 can mean so many
>>      > things their are multiple levels, options and details required
>>      to properly implement it.  I highly suspect its not an
>>      > afternoon event, I could be wrong if the right library is found
>>      thats license compatible.
>>
>>      There are a couple, T(w/o)oLame comes to mind.
>>      (http://www.twolame.org/ LGPL licensed) Any pointers as to which
>>      capabilities are needed in such a library? It seems the libraries
>>      are as outdated as the codec. :)
>>
>
>
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