A
few comments in response:
-
RFC 2190 should only be used for H.263 that pre-date 1998 in syntax design
(i.e., no use of PLUSPTYPE header format).
-
RFC 2429 is a better design than 2190, and 2429 can be used for both old and
newer versions of H.263 syntax.
Regarding the questions:
1) I don't think RFC 2190 any
prohibition against having additional GOB headers within Mode A
packets. The RFC says it "allows fragmentation at GOB boundaries", but
I don't see anywhere where it says it *requires* such fragmentation or
prohibits GOB headers within packets.
2) As far as the H.263 standard (and within RFC 2190, I
believe) is concerned, it is up to the discretion of the encoder when to
send GOB headers and when not to. Even within a single coded
picture, some GOBs can have headers while others do not. In some
particular system environments (e.g. in some H.32x environments), there are
ways to indicate that GOB headers should be sent or do not need to be
sent for all GOBs - but this is outside the scope of H.263 itself.
There is nothing in the H.263 video spec itself that requires any particular
behavior for whether GOB headers are present or not.
3) Given the above statements about item 1, I don't think item
3 is especially relevant anymore.
Best Regards,
Gary Sullivan
-----Original
Message-----
From: avt-admin@ietf.org [mailto:avt-admin@ietf.org]
On Behalf Of Muni Chandra
Sent: Saturday, June 28, 2003
5:07 AM
To: avt@ietf.org
Subject: [AVT] RFC 2190 :
Clarification
Hello
I am working on the implementation part of
RFC 2190
for H.263 video packtization.
I have a clarification.
1) As per RFC 2190, In MODE A,
beginning of Packet should contain GOB with its Header. So, this means
only first GOB (or part of it) in each packet should contain GOB
header, rest GOBs will not have GOB header in the same MODE-A
packet.
2) But H.263 standard says ( this with
respective to my discussion with H.263 developers) whether all GOB's
should have headers and all should not have GOB headers in a paerticular
frame.
3) So to acheive above point 1 with
respective above point 2, we need to calculate header for all GOB's
and transmit GOB header only for first GOB of each MODE - A
packet.
Please clarify above point 3 is correct or we
can calculate GOB headers for only first GOB of each MODE -A packet. So
that we can save time of GOB header computation at rest of
GOBs.
Thanking you in Advance
Muni Chanra Reddy
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