Author: diego
Date: Mon Mar 3 18:00:11 2008
New Revision: 653
Log:
misc spelling/wording/grammar fixes
Modified:
docs/nut.txt
Modified: docs/nut.txt
============================================================
==================
--- docs/nut.txt (original)
+++ docs/nut.txt Mon Mar 3 18:00:11 2008
 -82,8
+82,8 dts
EOR frames
End of relevance frames indicate that a given stream is
not relevant
- for presentation begining with the EOR frame and until
the following
- keyframe. This is primarely intended for periods were
subtitles are
+ for presentation beginning with the EOR frame and until
the following
+ keyframe. This is primarily intended for periods where
subtitles are
not displayed. But it is not limited to subtitles.
-1023,10
+1023,10 Decoding can only start at a keyframe. T
least a granularity of N seconds is wanted, then it is
neccessary to have
at least 1 keyframe every N seconds in every stream.
-Furthermore to start correct "presentation"
(after seeking) it is neccessary
+Furthermore, to start correct "presentation"
(after seeking) it is necessary
to have a decoded frame from every stream at approximately
the same time.
Thus it is important to have closely placed keyframes in
all streams at least
-once every N seconds. This is equivalent of having back
pointers frequently
+once every N seconds. This is equivalent to having back
pointers frequently
short.
Good example:
Video:
.....K...........................................K..........
.
-1045,7
+1045,7 shortest back ptrs: <-----------------
In the bad example a player would have to demux and decode
half of the video
between the 2 keyrames to start correct playback if it
favors the shortest
-back ptr.
+back pointer.
The above considerations are not specific to NUT.
-1089,15
+1089,15 B. forward seeking
1a. Perform a binary search on the syncpoint timestamps
finding the one
which is smallest and >= the target timestamp.
1b. Perform a binary search on the syncpoint back
pointers finding the
- smallest one which has a back ptr >= the position of
what was found in 1.
+ smallest one which has a back pointer >= the
position found in 1.
2. Follow the back pointer to the corresponding syncpoint.
-Alternatively a demuxer can search for a shorter back ptr
(which ensures that
-keyframes in all streams are closer together) before 2.
+Alternatively a demuxer can search for a shorter back
pointer (which ensures
+that keyframes in all streams are closer together) before
2.
One way to do this for backward seeking is:
-if the back ptr is longer than the demuxer wants, step back
by half the ptr,
-search for another syncpoint and repeat until either the
ptr is short enough
-or the search went too far.
+If the back pointer is longer than the demuxer wants, step
back by half the
+pointer, search for another syncpoint and repeat until
either the pointer is
+short enough or the search went too far.
Seeking with an index (non-normative):
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