[NUT-devel] Info packets in NUT stream (spec bugs?)

[Oded Shimon]

On Thu, Nov 16, 2006 at 12:12:53AM +0100, Michael Niedermayer wrote:
> On Wed, Nov 15, 2006 at 11:29:12PM +0100, Michael Niedermayer wrote:
> > also you dont need syncpoints over TCP, its a waste of bandwidth ...
> 
> heres a simple nut streaming spec proposal (whats not explicitly overriden
> is as defined by the current nut spec)
> 
> streaming in general:
> * nut is transmitted raw (no extra headers)
> * info may change and be transmitted anywhere
> * the client can (if supported by the server do seeks, ask for header or
>   info retransmitts, and ask for intra refresh (keyframe), and request
>   a syncpoint)
> 
> streaming over error free channels:
> * main, stream and info headers MUST NOT be repeateded unless requested by
>   the client and supported by the server
> * there is only 1 syncpoint after the headers unless server side seeking
>   is supported and used
> -----
> streaming over channels with packet loss:
> * packet boundaries are aligned with nut frame starts where possible
> * packet boundaries are aligned with slice starts where possible
> * FLAG_CODED_PTS SHOULD be set for all frames which use a frame from
>   a previous packet to calculate the pts
> * if the packet starts with a framecode then it MUST have FLAG_CHECKSUM
>   set (that way packets which continue past packets can be distinguished
>   from packets starting new frames)


This doesn't seem like a streaming protocol, more like a butchering of the 
nut spec (most obvious, allowing syncpoints not be written - this is an 
obvious violation of max_distance). This doesn't necessarily make it a bad 
idea (if you are completely error free, and not seeking, syncpoints are 
redundant and non-trivial to calculate for their back_ptr), but it does 
not seem like something to be written in a seperate document and being 
called a "streaming protocol" - it's a modified NUT format spec for 
streaming... And I think it's probably a bad idea to have several modified 
specs (it's somewhat like mpeg-ts, mpeg-ps, mpeg-bla).

- ods15