[Freeswitch-users] MP2

[Thomas Auge]

There seems to be: http://www.underbit.com/resources/mpeg/audio/compliance

Someone from the TwoLAME list recommended libMAD: http://www.underbit.com/products/mad/ ... it's GPL. Might be a good 
option.


On 03.01.2015 14:57, Steve Underwood wrote:
> Is there a standard set of test vectors for an MP2 decoder, and are they
> expected to give bit exact results?
>
> Steve
>
> On 01/04/2015 01:27 AM, Thomas Auge wrote:
>> 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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