There are some interesting ideas in these works and I would like to add a contribution to the discussion: from my point of view, preserving the transmitted events scheduling with a maximum accuracy is important as this scheduling is part of the musical information itself. However, except considering that the protocol is intented to run on a fast local dedicated network, the transport latency will introduce an important time distortion. Therefore, a mecanism to compensate for the latency variation seems to me to be necessary. Another point is the efficient use of the transmitted packets: sending one packet for each event is probably not the best solution. In this case and due to the underlying protocols overhead, the useful information part of a packet may become less than 10% of the packet size. Moreover, hardware layers such as Ethernet for example, often require a minimum packet size to operate correctly. There are solutions to these problems: I've recently presented a paper at WedelMusic 2001 which take account of efficiency, scheduling and clock skew. Maybe, combining the different things may result in a improved solution. You can temporarely get the paper at http://www.grame.fr/~fober/RTESP-Wedel.pdf -df
---------------------------------------------- Dominique Fober <[EMAIL PROTECTED]> ---------------------------------------------- GRAME - Centre National de Creation Musicale - 9 rue du Garet 69001 Lyon France tel:+33 (0)4 720 737 06 fax:+33 (0)4 720 737 01 http://www.grame.fr >> But from what I understand of RTP the same >> thing would/could happen if the protocols are switched. > >Yes, using RTP isn't about getting QoS for free -- > >BTW, some LAD-folk may not be aware that sfront networking: > >http://www.cs.berkeley.edu/~lazzaro/nmp/index.html > >uses RTP for MIDI, we presented our Internet-Draft at IETF >52 in Salt Lake a few weeks ago: > >http://www.ietf.org/internet-drafts/draft-lazzaro-avt-mwpp-midi-nmp-00.txt > >and it received a good reception -- the odds are good that >it will become a working-group item for AVT. The bulk of >this I-D describes how to use the information in RTP to >handle lost and late packets gracefully in the context of >network musical performance using MIDI ... > > --jl > >------------------------------------------------------------------------- >John Lazzaro -- Research Specialist -- CS Division -- EECS -- UC Berkeley >lazzaro [at] cs [dot] berkeley [dot] edu www.cs.berkeley.edu/~lazzaro >-------------------------------------------------------------------------
