[payload] AD Evaluation: draft-ietf-avt-rtp-isac-04

[Richard Barnes <[e-mail]>]

Overall, this document looks in pretty good shape.  A couple of comments I
would like to get resolved before IETF LC:

Section 3.1., "Consult source code for details"
If the details are only specified in the source code, then the source needs
to be a normative reference.  And I would prefer to avoid that  :)  Better
to specify here how the BEI and FL fields are encoded.   Alternatively, if
the codec really does expect a combined BEI/FL field, you could specify
such a field here, opaque to the RTP layer.  However, you would at least
need to say how the recipient knows where this field starts and stops.

Section 3.2., "The length of the encoded data is variable and depends on the
signal characteristics and the target bit rate."
However, there's nothing in this section that tells a recipient how to
determine what this length is.

Section 3.3., "... verifying the CRC checksum ..."
Please specify which CRC function is to be applied, and how the CRC value
field is formatted.

Section 3.3., "If this value would exceed 255 at encoding..."
It sounds like the LEN field is a single octet unsigned integer.  Please
state that explicitly.

Section 9.2. Informative References.
Better path to source code would be "webrtc/
modules/audio_coding/codecs/isac"

Thanks,
--Richard