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RE: [AVT] Working group last call: JPEG-2000 payload format
Hello,
I read the two drafts. Before going to the IESG, It will be better if
the authors clarify some issues.
Here are my comments:
1- How can we identify the packets belonging to the same Codestream
(frame) (especially when using multiple RTP sessions). Don't you think
that we need to add a frame_id identifier?.
2- In section 4.1 of Draft-ietf-avt-rtp-jpeg2000-15.txt: you consider 90
KHz for the Timestamp, this is not enough for professional video using
JPEG2K: isn't better to leave this to the implementers?
3- Adding a payload header is an overhead, so smaller payload header
size is better. Now, why do we need "T" and "tile number" fields? You
said that many tiles may exist in the same packet, so in this case no
meaning of "tile number" and "T" fields?
4- Is the tp (type) field necessary?. The RTP payload has already the
payload type (PT) and we can use it instead of tp? If not this
information can be communicated out of band and can be optional as the
width and height in section 8.1!
5- Why do you use the fragment offset?. Isn't (for one RTP session) the
sequence number of the RTP packet enough?
When using multiple RTP sessions for layered video, the parser that
extracted the data for a particular layer (for a particular RTP session)
may be transmitted out of band also (the index file is stored either as
a separate file or as meta-data). The index file is transmitted to the
receiver also, so the receiver can rebuild the codestream.
6- Do we really need to have an MHD flag? The size of main header may be
about 300 bytes so is there any chance that this packet will be
fragmented?
7- For the priority field use (the example in section 1.3.1): the
receiver can select which parts of the codestream to decode without
using the priority field. It can rebuild the codestream and extract the
parts to decode by reading the main header?.
Cheers,
Ali
-----Original Message-----
From: Colin Perkins [mailto:csp at csperkins.org]
Sent: lundi 14 mai 2007 13:59
To: IETF AVT WG
Cc: Roni Even; Tom-PT Taylor
Subject: [AVT] Working group last call: JPEG-2000 payload format
This is to announce a working group last call on the RTP Payload
Format for JPEG-2000:
http://www.ietf.org/internet-drafts/draft-ietf-avt-rtp-jpeg2000-15.txt
http://www.ietf.org/internet-drafts/draft-ietf-avt-rtp-jpeg2000-
beam-06.txt
Please send any final comments on these drafts to the <avt at ietf.org>
mailing list by 28 May 2007. If no substantive comments are received
by that time, we will ask the IESG to consider these drafts for
publication as Proposed Standard RFCs.
Note that there is declared IPR on the "beam" draft:
https://datatracker.ietf.org/public/ipr_detail_show.cgi?ipr_id=697
--
Colin Perkins
http://csperkins.org/
_______________________________________________
Audio/Video Transport Working Group
avt at ietf.org
https://www1.ietf.org/mailman/listinfo/avt
_______________________________________________
Audio/Video Transport Working Group
avt at ietf.org
https://www1.ietf.org/mailman/listinfo/avt