[NUT-devel] [nut]: r169 - trunk/docs/nut-english.txt

[ods15]

Author: ods15
Date: Sat Oct 28 21:27:00 2006
New Revision: 169

Modified:
   trunk/docs/nut-english.txt

Log:
I'm too lazy to explain seeking again :)


Modified: trunk/docs/nut-english.txt
==============================================================================
--- trunk/docs/nut-english.txt	(original)
+++ trunk/docs/nut-english.txt	Sat Oct 28 21:27:00 2006
@@ -246,7 +246,14 @@
 to reset the last_pts context of all streams, and to find the appropriate
 syncpoint when seeking. Demuxing can only begin at syncpoints for proper
 last_pts context across all streams, including after seeking.
-back_ptr is explained in greater detail in the Seeking section.
+A back_ptr points to a previous syncpoint in the file. The area between
+the previous syncpoint and this one must contain a keyframe for every
+stream, with a pts lower than or equal to the timestamp of this syncpoint.
+This back_ptr is used for optimal seeking in files without an index.
+For compression, the back_ptr is relative to this syncpoint, and is
+divided by 16. The reason for this is that the minimum size for a
+syncpoint is 16 bytes:
+8 startcode + 1 forward_ptr + 1 timestamp + 1 back_ptr + 4 checksum + 1 frame_code
 
 Error Checking
 
@@ -280,3 +287,8 @@
 closest syncpoint startcode found, and resume demuxing from there. If
 possible, before the linear search, rewind to the last syncpoint seen, in
 case a syncpoint was already skipped due to demuxing damaged data.
+
+Seeking
+
+An in depth explanation of an optimal seeking algorithm can be found in
+http://wiki.multimedia.cx/index.php?title=NUT