Re: [AVT] New I-D on JVT/H.26L packetization (fwd)
Stephen Casner <casner@acm.org> Wed, 06 March 2002 03:23 UTC
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Date: Tue, 05 Mar 2002 19:11:00 -0800
From: Stephen Casner <casner@acm.org>
To: AVT WG <avt@ietf.org>
cc: Stephan Wenger <stewe@cs.tu-berlin.de>
Subject: Re: [AVT] New I-D on JVT/H.26L packetization (fwd)
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Misdirected to avt-admin. -- Steve ---------- Forwarded message ---------- Date: Wed, 06 Mar 2002 02:05:16 +0100 From: Stephan Wenger <stewe@cs.tu-berlin.de> To: philippe.gentric@philips.com, avt-admin@ietf.org, jvt-experts@mail.imtc.org Cc: miska.hannuksela@nokia.com, thomas Stockhammer <stockhammer@ei.tum.de> Subject: Re: [AVT] New I-D on JVT/H.26L packetization Folks, in order to avoid excessive cross-posting I'm going to answer on this Email only on the appropriate mailing list, which is avt@ietf.org. (the reflector of the AVT group in the IETF) If you are not on this list, I would suggest to subscribe. See www.ietf.org for info how to subscribe to IETF mailing lists. Best regards Stephan At 02:43 PM 3/5/2002 +0100, philippe.gentric@philips.com wrote: >Stephan, > >a few remarks about your draft: > >***************** > I dont see the lack of final status for NAL as a problem, on the contrary >I beleive that making sure that the (RTP) transport is independent of >the NAL internals is a key design issue. > >in this respect, you state that: > >"The RTP payload specification is designed to be > unaware of the bit string in the NALP payload." > >but you dont state explicitely what is the situation for NALP headers, >rather you write: > > "JVT Video-aware network elements such as Gateways can perform many > operations by handling only those byte buffers" > >but is this in the scope of a RTP payload format ? > > I dont think so, being able to re-packetize is a *extremely* nice > property of JVT/NAL. > >Fine, but why would you specify that in the RTP payload ? >same for the NALP type byte, why this table of value? > >****************** > I am -as you are- concerned about using the RFC2250 timestamp policy. > >You write: "Clearly, using the RFC2250-like timestamp disallows the exact >media > synchronization between different RTP receivers" > >if you mean not being able to synchronise with other RTP streams >then this is simply not acceptable. > >Also I dont understand the logic of the choice, specifically the statement: > >"A consequence of this new feature (it was available > before only in H.263++ [3]) is the complete decoupling of the > transmission time, the decoding time, and the sampling or > presentation time of slices and pictures" > >seams a bit extreme to me... > >Another way to look at this issue is to consider that these video codecs >behave like audio codecs with an arbitrarily complex interleaving scheme... > >moreover each fragment (slice) objectively HAS a presentation time stamp >which is the CTS (composition time stamp) of the corresponding Access Unit >(picture)... > >so what you need is an interleaving scheme that can re-order the fragments >and assign CTS to each ... for which I know a method ;-) > >the fact that you want to send fragments a long time before they are to be >used >is a separate (buffer management, etc) issue ... > >BTW the description of the example of usage of ERPS in 10.1 would need >some more details in terms of rationale (why exactly you want to spread >the I frame over 10 minutes is unclear) > > >regards, > > >Philippe Gentric >Software Architect >Philips MP4Net >philippe.gentric@philips.com >http://www.mpeg-4.philips.com > > >Stephan Wenger <stewe@cs.tu-berlin.de> >Sent by: avt-admin@ietf.org > >02/24/2002 18:27 > > To: avt@ietf.org > cc: thomas Stockhammer <stockhammer@ei.tum.de> >miska.hannuksela@nokia.com >(bcc: Philippe Gentric/LIM/CE/PHILIPS) > Subject: [AVT] New I-D on JVT/H.26L packetization > > Classification: > > > >Folks, > >My new draft for an RTP packetization scheme for JVT video (aka H.26L, aka >forthcoming MPEG-4 Part 10) is now available from the I-D archives as >ftp://ftp.ietf.org/internet-drafts/draft-wenger-avt-rtp-jvt-00.txt. > >This draft is under development by Tom, Miska, and myself since quite some >time. It is submitted by the authors, and not on behalf of the whole JVT >group, as there are people in this group who would prefer to see an >approach that is more aligned with other payload specifications, >particularly with the MPEG-4 multisl draft. > >While we have had more than 10 turnaround between us authors, this is still >a true -00 draft, with a lot of known (and undoubtly many unknown) >problems. Any help on spotting and solving such problems is, as usual, >appreciated. Also, the video coding standard, and particularly the Network >Adpatation Layer is not yet set in stone, and we hope to receive valuable >input at the AVT meeting to make the video coding itself more network >friendly. > >One of the key problems of the development (and the review) of this draft >is that JVT doesn't have a complete, accurate, and up-to-date description >of the video syntax, or, more precisely, the syntax of the Network >Adaptation Layer. A document describing this syntax and the rationales >behind it is currently in preparation, and I will advise you on this >mailing list as soon as it is available. For now, the references in the >draft will have to suffice. > >Best regards >Stephan > > >_______________________________________________ >Audio/Video Transport Working Group >avt@ietf.org >https://www1.ietf.org/mailman/listinfo/avt > _______________________________________________ Audio/Video Transport Working Group avt@ietf.org https://www1.ietf.org/mailman/listinfo/avt
- [AVT] New I-D on JVT/H.26L packetization Stephan Wenger
- Re: [AVT] New I-D on JVT/H.26L packetization philippe.gentric
- Re: [AVT] New I-D on JVT/H.26L packetization Stephan Wenger
- Re: [AVT] New I-D on JVT/H.26L packetization (fwd) Stephen Casner
- Re: [AVT] New I-D on JVT/H.26L packetization Colin Perkins
- Re: [AVT] New I-D on JVT/H.26L packetization philippe.gentric
- Re: [AVT] New I-D on JVT/H.26L packetization Magnus Westerlund
- Re: [AVT] New I-D on JVT/H.26L packetization Colin Perkins
- Re: [AVT] New I-D on JVT/H.26L packetization Colin Perkins
- Re: [AVT] New I-D on JVT/H.26L packetization Stephan Wenger
- Re: [AVT] New I-D on JVT/H.26L packetization Stephan Wenger
- Re: [AVT] New I-D on JVT/H.26L packetization philippe.gentric
- Re: [AVT] New I-D on JVT/H.26L packetization Stephan Wenger