Subject: [payload] AD review of draft-ietf-payload-vp8-08

From: Richard Barnes <[email-masked]>
Date: Tue, 16 Apr 2013 18:21:08 -0400

I reviewed this draft and have a couple of questions before IETF LC:

Major:

>From the current text, it seems like the frame reconstruction algorithm is
mostly clear:
1. Collect all packets with a given PictureID
2. Order packets by PartID
3. Go through packets in order, updating PartID as you go through each
packet.
4. If you get to the end of a packet with an incomplete partition, and the
PartID of the next packet is different from the current PartID (indicating
a lost packet), then discard the incomplete partition and:
4.1. If S=1, start a new partition at the beginning of the new packet
4.2. If S=0, skip to the next partition boundary in the new packet and
start a new partition starting there
Is this understanding correct?  In any case, it would really help
interoperability if you could write this algorithm down explicitly in the
document, probably around Section 4.4.  Note that this assumes that the
bitstream format has partition markers.

Minor:

The document refers several times to the "golden" and "altref" frames.
 However, I don't see it defined anywhere how these frames are set.  Is
this in the bit stream definition?

Section 4.2. says that the PartID MUST NOT be larger than 8.  But the field
is 4 bits long.  Is this correct?

In Section 4.2., there are 8- and 16-bit versions of the PictureID.  The
definition says that when the maximum ID is reached, the ID rolls over.
 MUST the length remain the same?

In the congestion control section, please add a note that the discarding of
non-reference frames cannot be done if the stream is encrypted (because the
non-reference marker is encrypted).