[vlc-devel] [RFC-PATCH 06/12] core: added BLOCK_FLAG_DISPLAY_FORCED

Filip Roséen filip at videolabs.io
Wed May 11 18:56:51 CEST 2016

This new block-flag is to be used when you need a certain block to be
displayed, even during preroll.

There are several applicable scenarios, but imagine that you are seeking
to the middle of two frames, and the next one is too far away for it to
be feasible for the user to sit and wait for that frame to appear.

It can be used when playing a file with a very low frame-rate, where the
next video picture is not to be displayed for a very long time (so you
want to play the previous picture, while still maintaining preroll to
seek to where the user has requested).


The below linked thread tries to solve the issue by always displaying
frames where "b_force" is true, something is not a very wise thing to

  - https://mailman.videolan.org/pipermail/vlc-devel/2016-March/106470.html

Instead, if a demuxer desides that it is indeed important for something
to be displayed during preroll; BLOCK_FLAG_DISPLAY_FORCED is now
 include/vlc_block.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/vlc_block.h b/include/vlc_block.h
index 59a9ef1..0e29b1a 100644
--- a/include/vlc_block.h
+++ b/include/vlc_block.h
@@ -82,6 +82,8 @@
 /** This block contains an interlaced picture with bottom field first */
+/** This block contains an entity that shall be displayed, even during preroll */
 /** This block contains an interlaced picture */

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