[Matroska-devel] Re: [Matroska-users] Some questions about matroska.....
steve.lhomme at free.fr
Wed Jan 12 09:49:06 CET 2005
Fabio Bizzi a écrit :
> Hi matroska guys,
> I'm new with matroska and I've some questions to this list, I've
> searched in the docs but I haven't found what I'm looking for.
> The first question is: Is Matroska "streammable" in multicast ?
> I've looked around for any documentation about streaming matroska in
> unicast / multicast but I'ven't fond any at all. :(
No. Multicast/RTP requires too many changes to the format to be usable.
The only streaming we recommend/support/endores is on TCP. UDP could
work as the format is working even with data loss. But RTP has more
constraint that would make it hard to work.
We had a discussion about that maybe 2 years ago and decided that it was
not a top priority to have this. But if you really want a definitive
answer we could have a look again.
From what I remember multicasting is good if the UDP packets are small
and "atomic". That means it represents a valid basic part of the stream.
But in Matroska the smaller level that can have error checking is the
BlockGroup, which can be huge for video since it contains a complete
frame (can be a few kilobytes)... Now for audio without lacing these
packets could be small and therefore usable.
> If Yes, Can I use RTP ? or what else ?
> DO I need a SAP server for announcements and Header, Meta Seek
> Information, Segment Information and Track ? Or What else ?
> Where I can found docs about it ?
> Thanks a lot.
All the doc we have is on the website or the ML. But if you have more
background on multicasting it could be helpful for us if you share it :)
Maybe I'm wrong about the needed atomic aspect of RTP/UDP. As even for a
1 Mbps stream the UDP packets for video will never match a video frame,
regardless of the format used.
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