[cvs-annodex] commit (/annodex): standards/draft-pfeiffer-annodex-current.xml

[silvia]

Update of /annodex (new revision 846)

Modified files:
   standards/draft-pfeiffer-annodex-current.xml

Log Message:
Fixed up the section on remuxing! Yay!



Modified: standards/draft-pfeiffer-annodex-current.xml
===================================================================
--- standards/draft-pfeiffer-annodex-current.xml	2005-02-06 07:19:28 UTC (rev 845)
+++ standards/draft-pfeiffer-annodex-current.xml	2005-02-06 07:21:52 UTC (rev 846)
@@ -1148,34 +1148,57 @@
       satisfies all these requirements is the correct seek position.
       </t>
       
+      <t>A player that presents from an offset has to take into account that
+      the bitstream may contain some packets that are only there to allow
+      accurate decoding of the seek time. When the backwards dependencies
+      were resolved for a specific logical bitstream, several non-relevant
+      Ogg pages of other logical bitstreams may also have ended up in the
+      intermediate. These have to be skipped by a player. The time that a
+      player has to start presenting from is given in the "presentationtime"
+      in the Skeleton.
+      </t>
+
       </section>
 
-      <section title="Remultiplexing bitstreams">
+      <section title="Remultiplexing a bitstreams">
 
       <t>When a subpart of an Annodex bitstream is requested, such as through
       a temporal URI query request from a Web server, the bitstream has to be
-      recomposed and a remultiplexed bitstream composed. There are several aims
-      to achieve on doing such a remultiplexing with as little effort as possible:
+      recomposed and a remultiplexed bitstream served out. There are several aims
+      for performing the remultiplexing with as little effort and therefore
+      as little delay as possible:
       <list style="symbols">
         <t>no decoding of the logical bitstreams is performed.</t>
         <t>no changes to the pages, in particular to the granule positions are made.</t>
         <t>changes occur only to the control section.</t>
-        <t>the data section is cut as little as necessary to allow simple
-           recombination of separate sections from caches.</t>
       </list>
       </t>
 
-      <t>xxx: how to actually do it xxx</t>
+      <t>The fields of the Skeleton track allow achievement of all these aims.
+      Remultiplexing is essentially achieved by seeking to the position as
+      described above and then including from each logical bitstream only the
+      relevant Ogg pages into the new stream. Changes to fields in the bitstream
+      are restricted to the control section:
+      <list style="symbols">
+        <t>the "presentationtime" has to be adjusted to the requested start time
+        </t>
+        <t>the "basegranule" for each logical bitstream has to be adjusted to the
+        granule position at which each logical bitstream starts. This is not the
+        first granule position of the Ogg pages included into the bitstream, but
+        rather the last one that did not get included, as it represents the start
+        time of the bitstream.
+        </t>
+      </list>
+      Everything else, and in particular the Ogg pages, stay the same. This is
+      important also to allow caching of such files as is required for Web proxies.
+      </t>
 
       </section>
 
-       
-      <section title="Decoding with time offsets">
+      <section title="Caching of Annodex in caching Web proxies">
 
-      <t>presentation time ...
+      <t>xxx</t>
 
-      </t>
-
       </section>
 
     </section>
@@ -2014,8 +2037,8 @@
     </section>
     
     <section title="Acknowledgments">
-      <t>The authors greatly acknowledge the contributions of Zentaro
-      Kavanagh, Andrew Nesbit and Simon Lai in developing this 
+      <t>The authors greatly acknowledge the contributions of Rob Collins,
+      Zentaro Kavanagh, Andrew Nesbit and Simon Lai in developing this 
       specification.
       </t>
     </section>


-- 
silvia