LibVideo/Matroska: Stop skipping a cue when seeking forward

This would cause seeks where the approximate starting cue index was one
cue before the optimal cue to not change the sample iterator position.
Fixing this issue improves accurate seek speeds significantly.

1 files changed, 1 insertions, 2 deletions

diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
index ddde35366e..a0e9c780f0 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
@@ -798,12 +798,11 @@ DecoderErrorOr<void> Reader::seek_to_cue_for_timestamp(SampleIterator& iterator,
     }
 
     while (index < cue_points.size()) {
-        auto const& cue_point = cue_points[index++];
+        auto const& cue_point = cue_points[++index];
         dbgln_if(MATROSKA_DEBUG, "Checking future cue point {}ms", cue_point.timestamp().to_milliseconds());
         if (cue_point.timestamp() > timestamp)
             break;
         prev_cue_point = &cue_point;
-        index++;
     }
 
     TRY(iterator.seek_to_cue_point(*prev_cue_point));