Re: [codec] #1: Application: 2.1. Point to point calls supporting transcoding?

Any testing of tandem coding can only be about the audio quality.  
There is no binary question about whether "it works" or not, because  
any two codecs do indeed work together when connected through audio.

I don't see a need to add tandem testing to the requirements.  Quality  
will be high when operating towards the high end of the range in  
bitrates mentioned in the requirements, and tandem quality will be  
limited by the other codec. For lower bitrates the quality naturally  
goes down.. not sure what to test?

koen.

Quoting stephen botzko:
> I personally believe testing tandem operation is a MUST, since devices using
> this CODEC will certainly connect into networks where it is not supported.
> The idea below that this will "just work" with every ITU codec is
> incorrect..
>
> In addition, tandem operation occurs in virtually all conference bridges
> (including back-to-back encode/decode with CODEC itself).  So surely
> self-tandeming has to be tested anyway.  (Though of course is is common for
> devices in the same conference to be using different codecs).
>
> I do not favor just copying the tandem requirements from some other codec's
> test plan - unless we are sure that it is in essentially the same ecosystem
> as ours.  Ideally the community would identify common use cases, and the
> test cases would be derived from those cases.
>
> Stephen Botzko
>
> On Sat, Apr 3, 2010 at 1:39 AM, codec issue tracker  
> <trac@tools.ietf.org>wrote:
>
>> #1: Application: 2.1.  Point to point calls supporting transcoding?
>>
>> ------------------------------------+---------------------------------------
>>  Reporter:  hoene@...                 |       Owner:
>>     Type:  enhancement             |      Status:  new
>>  Priority:  major                   |   Milestone:
>> Component:  requirements            |     Version:
>>  Severity:  Active WG Document      |    Keywords:
>>
>> ------------------------------------+---------------------------------------
>>
>> Comment(by hoene@...):
>>
>>  No consensus either until now. Again two opinions:
>>
>>  a) "To have similar requirements as G.718 and to consider at least cross
>>  tandeming conditions with G722.2@12.65 in the characterization phase."
>>
>>  b) "I think that transcoding must be an explicit non-goal for this codec."
>>  "Sorry, but I still do not understand the need for this testing.  In a
>>  cell network to VoIP topology, the codec selected must be an ITU codec
>>  which we already know are working fine for transcoding.  In a VoIP to VoIP
>>  topology the codec selected is the one defined by this WG and by
>>  definition no transcoding is needed.  And that's it, no test needed,
>>  because nobody will use it this way."
>>
>>  Again, I would suggest to look for volunteers who want to make the
>>  subjective tests with G.722.2 and CODEC.
>>
>> --
>> Ticket URL: <https://svn.tools.ietf.org/wg/codec/trac/ticket/1#comment:1>
>> codec <http://tools.ietf.org/codec/>
>>
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>