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

[Oded Shimon]

On Mon, Nov 06, 2006 at 01:44:19PM +0100, Michael Niedermayer wrote:
> On Mon, Nov 06, 2006 at 10:56:57AM +0200, Oded Shimon wrote:
> > On Sun, Nov 05, 2006 at 09:32:44PM +0200, Oded Shimon wrote:
> > > On Sun, Nov 05, 2006 at 07:07:22PM +0100, Michael Niedermayer wrote:
> > > > On Sun, Nov 05, 2006 at 09:48:46AM +0200, Oded Shimon wrote:
> > > > > On Sun, Nov 05, 2006 at 12:19:53AM +0100, Michael Niedermayer wrote:
> > > > > > the big problem with simply allowing arbitrarily placed info is that it 
> > > > > > makes the info useless for the normal nut file case as the info cannot be
> > > > > > found its like a dvd with chapters but the information about where the
> > > > > > chapters begin is stored at the begin of the chapters, you end up with
> > > > > > a O(n) search ...
> > > > > > so ive some concerns with just saying its ok for streaming, as that
> > > > > > leads to nut files laying around which are encoded for streaming ...
> > > > > 
> > > > > The proposal I had for this is - info packets not written after main 
> > > > > headers are only allowed in real time streaming, and must have 
> > > > > chapter_id!=0, and any info packets written after main headers, both in 
> > > > > file and in streaming scenario, MUST be repeated together with all main 
> > > > > headers. No demuxer would have to search anything past main headers, any 
> > > > > info packets given during demuxing is "information update". In the file 
> > > > > scenario, all info must be written after the main headers, so no searching 
> > > > > necessary.
> > > > 
> > > > hmm, rich what is your oppinion about that? iam unsure if iam against it
> > > > or not ...
> > > 
> > > - ods15
> > 
> > Objections? Commit? 48 hour notice from now.
> 
> i object until i heard a comment from at least rich, comments from
> everyone else are of course welcome too

This is a new proposal: Basically identical to the previous one, only info 
packets SHOULD NOT appear "in the wild" in non-realtime-streams instead of 
MUST NOT. Making the distinction between file and realtime streams less 
strict. Demuxers still SHOULD NOT search for info packets anywhere except 
after the main headers. I think this is most clean...

Comments?

- ods15
-------------- next part --------------
Index: nut.txt
===================================================================
--- nut.txt	(revision 20666)
+++ nut.txt	(working copy)
@@ -180,11 +180,15 @@
             packet_header, index_packet, packet_footer
         }
         if (!eof) while(next_code != main_startcode){
-            if(next_code == syncpoint_startcode){
-                packet_header, syncpoint, packet_footer
+            packet_header, syncpoint, packet_footer
+            do{
+                frame
+            }while(next_code == framecode);
+            reserved_headers
+            while(next_code == info_startcode){
+                packet_header, info_packet, packet_footer
+                reserved_headers
             }
-            frame
-            reserved_headers
         }
     }
 
@@ -836,9 +840,15 @@
 Info:
 -----
 
-If a info packet is stored anywhere then a muxer MUST also store an identical
+All info packets stored after a main header set MUST also have an identical
 info packet after every main-stream-header set
 
+All info packets not stored after a main header set MUST have
+chapter_id!=0 .
+
+Info packets SHOULD be written after main header sets in non realtime
+streams.
+
 If a demuxer has seen several info packets with the same chapter_id and
 stream_id then it MUST ignore all but the one with the highest position in
 the file