Subject: [AVT] AVC ready with NI-C packetization rules

From: "Karen Harrison (harrison)" <[email-masked]>
Date: Thu, 8 Apr 2010 13:35:29 -0700

Hello,

draft-ietf-avt-rtp-svc-20.txt describes an AVC ready stream as a stream
that can be processed by an ietf-avt-rtp-rfc3984bis compatible receiver.
Assuming that a stream is transmitted using the MST mode with NI-C
packetization rules, is it possible to send a base layer RTP session
such that the layer is AVC ready without requiring that an intermediate
MANE device remove NAL units?   Specifically, with the NI-C rules is it
required that the PACSI NAL units (type 30) and prefix NAL units (type
14) be present in the base layer?

Thanks,

Karen Harrison

---

From: Ye-Kui Wang <[email-masked]>
Date: Thu, 08 Apr 2010 17:29:03 -0400

Hi,
 
Could you please point out where in the draft the following is said?
 
"Specifically, with the NI-C rules is it required that the PACSI NAL units
(type 30) and prefix NAL units (type 14) be present in the base layer?"
 
In any case, I think the answer to you main question is yes. 
 
Being "AVC-ready" means that no "useful NAL units", which are supposed to be
passed by the rfc4984bis receiver to a decoder, are encapsulated in new
packet types defined in the SVC draft, because if that happens then those
"useful NAL units" will get ignored/discarded by the rfc4984bis receiver. 
 
If PACSI NAL units and prefix NAL units are present, PACSI NAL units will be
discarded by the rfc4984bis receiver, and prefix NAL units will be passed to
the H.264/AVC decoder and then ignored/discarded by the decoder. 
 
BR, YK

  _____  

From: [email-masked] [mailto:[email-masked]] On Behalf Of Karen
Harrison (harrison)
Sent: Thursday, April 08, 2010 4:35 PM
To: [email-masked]
Subject: [AVT] AVC ready with NI-C packetization rules

Hello,

draft-ietf-avt-rtp-svc-20.txt describes an AVC ready stream as a stream that
can be processed by an ietf-avt-rtp-rfc3984bis compatible receiver.
Assuming that a stream is transmitted using the MST mode with NI-C
packetization rules, is it possible to send a base layer RTP session such
that the layer is AVC ready without requiring that an intermediate MANE
device remove NAL units?   Specifically, with the NI-C rules is it required
that the PACSI NAL units (type 30) and prefix NAL units (type 14) be present
in the base layer?

Thanks,

Karen Harrison

---

From: "Karen Harrison (harrison)" <[email-masked]>
Date: Sun, 11 Apr 2010 11:20:30 -0700

Hi Ye-Kui,

Thanks for your response.

Just to restate. A SVC packetizer when following NI-C packetization
rules is not capable of generating a base layer that does not contain
PACSI NAL units so it is incumbent on  either a MANE device or
rfc3984bis receiver to discard the PACSI NAL units (to be compliant with
an AVC ready stream).  A PACSI NAL unit contains the CS-DON that is used
for reordering packets at the receiver so this is why the PACSI is
present in the base layer. 

Likewise, in support of temporal scalability, prefix NAL units will be
generated for a base layer by a SVC encoder.  Again, it is the
responsibility of a MANE device, the rfc39848bis receiver or H.264/AVC
decoder to discard the prefix NAL units.

On page 51 (draft-ietf-avt-rfc-svc-20.pdf) the NI-C packetization rules
describe the use of the CS-DON for identifying the NAL decoding order.
>From this section I assumed that PASCI NAL units are required at base
layer.

Regarding the prefix NAL units, referring to page 47, I made an
assumption that if two receivers, one AVC and the other SVC, received
the same base layer that the base layer must contain prefix NAL units
because the SVC decoder expects the prefix NAL units for temporal
decoding.

Karen

From: Ye-Kui Wang [mailto:[email-masked]] 
Sent: Thursday, April 08, 2010 4:29 PM
To: Karen Harrison (harrison); [email-masked]
Subject: RE: [AVT] AVC ready with NI-C packetization rules

Hi,

"Specifically, with the NI-C rules is it required that the PACSI NAL
units (type 30) and prefix NAL units (type 14) be present in the base
layer?"

Being "AVC-ready" means that no "useful NAL units", which are supposed
to be passed by the rfc4984bis receiver to a decoder, are encapsulated
in new packet types defined in the SVC draft, because if that happens
then those "useful NAL units" will get ignored/discarded by the
rfc4984bis receiver. 

If PACSI NAL units and prefix NAL units are present, PACSI NAL units
will be discarded by the rfc4984bis receiver, and prefix NAL units will
be passed to the H.264/AVC decoder and then ignored/discarded by the
decoder. 

BR, YK

________________________________

	From: [email-masked] [mailto:[email-masked]] On
Behalf Of Karen Harrison (harrison)
	Sent: Thursday, April 08, 2010 4:35 PM
	To: [email-masked]
	Subject: [AVT] AVC ready with NI-C packetization rules

	Hello,

	draft-ietf-avt-rtp-svc-20.txt describes an AVC ready stream as a
stream that can be processed by an ietf-avt-rtp-rfc3984bis compatible
receiver.  Assuming that a stream is transmitted using the MST mode with
NI-C packetization rules, is it possible to send a base layer RTP
session such that the layer is AVC ready without requiring that an
intermediate MANE device remove NAL units?   Specifically, with the NI-C
rules is it required that the PACSI NAL units (type 30) and prefix NAL
units (type 14) be present in the base layer?

	Thanks,

	Karen Harrison

---

From: Ye-Kui Wang <[email-masked]>
Date: Mon, 12 Apr 2010 11:59:40 -0400

Hi Karen,
 
Thanks. Just one more clarification. The rfc3984bis receiver should pass
prefix NAL units to the decoder, unless the prefix NAL units are
encapsulated in the payload of an unknow packet type, and it is the
responsibility of the decoder to handle NAL unit types defined by the codec
specification, though that definition could be "reservered". This is to
enusre the payload format specification applies to future codec extensions.
If the rfc3984bis receiver discards NAL units reserved by the codec
specification, then this aspect is broken. 
 
BR, YK

  _____  

From: Karen Harrison (harrison) [mailto:[email-masked]] 
Sent: Sunday, April 11, 2010 2:21 PM
To: Ye-Kui Wang; [email-masked]
Subject: RE: [AVT] AVC ready with NI-C packetization rules

Hi Ye-Kui,

Just to restate. A SVC packetizer when following NI-C packetization rules is
not capable of generating a base layer that does not contain PACSI NAL units
so it is incumbent on  either a MANE device or rfc3984bis receiver to
discard the PACSI NAL units (to be compliant with an AVC ready stream).  A
PACSI NAL unit contains the CS-DON that is used for reordering packets at
the receiver so this is why the PACSI is present in the base layer. 

On page 51 (draft-ietf-avt-rfc-svc-20.pdf) the NI-C packetization rules
describe the use of the CS-DON for identifying the NAL decoding order.  From
this section I assumed that PASCI NAL units are required at base layer.

Regarding the prefix NAL units, referring to page 47, I made an assumption
that if two receivers, one AVC and the other SVC, received the same base
layer that the base layer must contain prefix NAL units because the SVC
decoder expects the prefix NAL units for temporal decoding.

Karen

Hi,

BR, YK

  _____  

Hello,

Thanks,

Karen Harrison