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Re: Gen-ART review of draft-ietf-avtext-client-to-mixer-audio-level-05.txt

2011-09-27 13:04:50
Hey Alexey,

On 27 sept. 2011, at 00:24, Alexey Melnikov 
<alexey(_dot_)melnikov(_at_)isode(_dot_)com> wrote:

Jonathan Lennox wrote:

Hi, Alexey -- thank you for the Gen-ART review.

Hi Jonathan,

Alexey Melnikov writes:

Question: are the two encoding of the audio level indication option 
specified in the document really necessary?
  

Do you mean the one-byte vs. two-byte forms of the header extension (Figure 
1 vs. Figure 2)?  These are the two forms of the generic header extensions 
defined by RFC 5285.

I understood that. Does RFC 5285 require that both forms should be allowed?

It doesn't explicitly say so but it It actually does, yes. Here's what it says:

   A stream MUST contain only one-byte or two-byte
   headers: they MUST NOT be mixed within a stream.

Audio level headers can find themselves in streams that also have other, longer 
extensions, which do require the two-byte header. The above lines mandate that 
in such cases they all use the two-byte header.

In the same regard, although probably a bit less likely, nothing prevents 
having another sixteen header extensions in a stream that also has levels. In 
that case we'd need to switch to two-byte headers in order to be able to fit 
all the IDs.

Cheers,
Emil

--sent from my mobile

In general, it would be good to avoid multiple representations of the same 
thing.

The actual payload (one byte containing the V and level bits) is identical 
in the two cases; the only difference is the container.  We can add some 
text clarifying this point if you think it would be helpful.

Nits/editorial comments:
s/relys/relies ???
  
Thanks, will fix.


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