Re: [AVTCORE] Magnus Westerlund's Discuss on draft-ietf-payload-rtp-ttml-03: (with DISCUSS and COMMENT)
James Sandford <james.sandford@bbc.co.uk> Tue, 29 October 2019 14:24 UTC
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From: James Sandford <james.sandford@bbc.co.uk>
To: Magnus Westerlund <magnus.westerlund@ericsson.com>, "iesg@ietf.org" <iesg@ietf.org>
CC: "avtcore-chairs@ietf.org" <avtcore-chairs@ietf.org>, "draft-ietf-payload-rtp-ttml@ietf.org" <draft-ietf-payload-rtp-ttml@ietf.org>, "avt@ietf.org" <avt@ietf.org>
Thread-Topic: [AVTCORE] Magnus Westerlund's Discuss on draft-ietf-payload-rtp-ttml-03: (with DISCUSS and COMMENT)
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Date: Tue, 29 Oct 2019 14:24:13 +0000
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Subject: Re: [AVTCORE] Magnus Westerlund's Discuss on draft-ietf-payload-rtp-ttml-03: (with DISCUSS and COMMENT)
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Changes have been submitted in -05. https://datatracker.ietf.org/doc/draft-ietf-payload-rtp-ttml/ Regards, James ========== James Sandford R&D Project Engineer BBC Research and Development 5th Floor Dock House MediaCityUK Salford M50 2LH Tel: 030304 (09549) Web: http://www.bbc.co.uk/rd ________________________________________ From: Magnus Westerlund [magnus.westerlund@ericsson.com] Sent: 29 October 2019 14:13 To: James Sandford; iesg@ietf.org Cc: avtcore-chairs@ietf.org; draft-ietf-payload-rtp-ttml@ietf.org; avt@ietf.org Subject: Re: [AVTCORE] Magnus Westerlund's Discuss on draft-ietf-payload-rtp-ttml-03: (with DISCUSS and COMMENT) Hi James, Looks good to me. Thanks, Magnus On Tue, 2019-10-29 at 13:52 +0000, James Sandford wrote: > Thank you for your further comments. > > I will make the suggested changes to Section 8 and Section 11.1. > > With regards to further clarifying the fragmentation of documents, I propose > the following: > > Section 6 OLD: > If a TTML document is assessed to be invalid then it MUST be discarded. When > processing a valid document, the following requirements apply. > > Section 6 NEW: > If a TTML document is assessed to be invalid then it MUST be discarded. This > includes empty documents, i.e. those of zero length. When processing a valid > document, the following requirements apply. > > Section 8 ADDITIONAL PARAGRAPH: > As described in Section 6, only zero or one TTML document may be active at > any point in time. As such, there MUST only be one document transmitted for a > given RTP Timestamp. Furthermore, as stated in Section 4.1, the Marker Bit > MUST be set for a packet containing the last fragment of a document. A packet > following one where the Marker Bit is set contains the first fragment of a new > document. The first fragment might also be the last. > > > Regards, > James > > > ========== > James Sandford > R&D Project Engineer > > BBC Research and Development > 5th Floor > Dock House > MediaCityUK > Salford > M50 2LH > > Tel: 030304 (09549) > Web: http://www.bbc.co.uk/rd > > ________________________________________ > From: Magnus Westerlund [magnus.westerlund@ericsson.com] > Sent: 29 October 2019 11:47 > To: James Sandford; iesg@ietf.org > Cc: avtcore-chairs@ietf.org; draft-ietf-payload-rtp-ttml@ietf.org; > avt@ietf.org > Subject: RE: [AVTCORE] Magnus Westerlund's Discuss on draft-ietf-payload-rtp- > ttml-03: (with DISCUSS and COMMENT) > > Hi James, > > Thanks for the many updates in -04. However, I think there are a couple of > adjustments still needed. > > Section 8: > > When a document spans more than one RTP packet, the entire document > is obtained by concatenating User Data Words from each contributing > packet in ascending order of Sequence Number. > > I think this can be further clarified by adding "consecutive" > > When a document spans more than one RTP packet, the entire document > is obtained by concatenating User Data Words from each consecutive > contributing > packet in ascending order of Sequence Number. > > What I think is unclear is what is considered contributing packets. It is > quite common that one determine fragments based on timestamp and that may be > assumed by some. I don't know if that is a dangerous assumption here. To my > understanding one can determine the set of fragments by looking at the > marker bit for the packets. From first 0 after a 1, until and including the > packet with a m=1. If that is your intention for how one should do it, so > that it works for multiple documents to share epoch and thus RTP timestamp > documents I think this needs to be made explicit. > > In section 11.1 it says: > > In these situations, it is RECOMMENDED that streams use > the same Synchronization Source and Clock Rate as the related media. > > You do need to insert "Time" before Synchronization source to not be > misinterpret to mean SSRC. Or maybe better is to say "clock source". > > Cheers > > Magnus Westerlund -- Cheers Magnus Westerlund ---------------------------------------------------------------------- Networks, Ericsson Research ---------------------------------------------------------------------- Ericsson AB | Phone +46 10 7148287 Torshamnsgatan 23 | Mobile +46 73 0949079 SE-164 80 Stockholm, Sweden | mailto: magnus.westerlund@ericsson.com ----------------------------------------------------------------------
- [AVTCORE] Magnus Westerlund's Discuss on draft-ie… Magnus Westerlund via Datatracker
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… Magnus Westerlund
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… James Sandford
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… Magnus Westerlund
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… James Sandford
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… Magnus Westerlund
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… James Sandford
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… Christer Holmberg
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… Christer Holmberg
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… Magnus Westerlund
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… Magnus Westerlund
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… James Sandford
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… Christer Holmberg
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… Christer Holmberg
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… James Sandford
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… Christer Holmberg
- Re: [AVTCORE] Magnus Westerlund's Discuss on draf… James Sandford