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Re: [AVT] I-D ACTION:draft-ietf-avt-variable-rate-audio-00.txt
Hi, Stephan,
Stephan Wenger wrote:
...
Or, we can make uRTR a standard _option_ to all payloads - e.g., whenever
rate param is set to 192kHz (or whatever value we end up with), it would
mean that uRTR is in use, if rate is set to any other value, it implies
that the actual sampling rate is in use.
I don't like optional mechanisms very much -- they are not good for
interoperability, and increase the implementation burden.
Of cause, you don't have to call it "optional" ;-)
Also, what would you do as a receiver if you get a-law with 192 kHz signaled
sample rate -- use 8 kHz (which would be the common use of a-law) or 192 kHz
(which would be a perfectly legal use case as well)?
Well, I am thinking that individual payload formats will be allowed to decide whether or not
to support uRTR when they are defined. For instance, if the payload format is being defined
for a-law, the RFC could say "uRTR is not supported" since it would not add any value to it.
In such a case, signaling 192 kHz to the receiver would be an error. On the other hand, when
a codec considers variable rate operation an integral part of its capability (e.g., vmr-wb,
amr-wb+), the corresponding payload specs could then explicitly say "uRTR SHOULD be supported."
regards,
-Qiaobing
Stephan
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