Re: [rohc] Feedback formats

Klaus, Cai,

Using the "short cut" as Klaus describes below is not really allowed in
RFC3095. Section 5.6.1 is quite clear that all feedback during a mode
transition must carry a CRC option. The mode parameter must also be set
to O to transfer from U-mode to O-mode. FEEDBACK-1 doesn't have a mode
field and cannot carry feedback options.

Klaus, I guess you refer to the last paragraph of section 5.6.2. It
should not be interpreted by its own. I agree that the wording is a bit
unfortunate, but I can still not see how it can be interpret it this
way. FEEDBACK-1 cannot be used for mode transfer between U-mode and
O-mode. The compressor simply don't have the information to which mode
to transfer to.

Cheers,

/Calle

Klaus Warnke wrote:
> Hello cai,
> 
> I'm not completely sure what your mean.
> 
> First, there is a "short cut" to switch from U to O
> mode (5.6.2.). In this case, a feedback-1 is sufficient, because
> the receiving of any feedback shows to compressor that a feedback
> channel is available and this is the precondition for bidirectional
> optimistic mode.
> 
> Ideally the mode transition should be profile independent. But for the
> IR/IR-DYN packet it isn't due to a design flaw. Only the dynamic chain
> of the RTP Header contains the 'M' (5.7.7.6.) flag to transmit a
> compression mode. For the other profiles you must use a extension-3.
> 
> Hope that helps.
> 
> If not, could you please explain the problem more detailed?
> 
> br
> Klaus Warnke
> 
> 
> cai.wei2@zte.com.cn wrote:
>> RFC 3095 describes that when mode transitions, any feedback should be
>> sent with mode transition parameter;
>>
>> at the same time, the feedback logic of decompressor in U/O/R mode
>> also send feedback with mode parameter.
>>
>> there is a doubt that which case we could use feedback-1 in profile RTP?
>>
>> Thanks
>> 	
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