Hi.
I am investigating Kdenlive bug http://kdenlive.org/mantis/view.php?id=2219
where moving groups of clips corrupts the timeline. I traced the bug to a
problem in MLT's playlist "consolidate_blanks" routine.
The problem is a bit complicated, I will try to do my best to describe: the
playlist gets corrupted, with blank clips having the wrong length (usually a
blank with length 15000 appears where it should be longer.
Looking at MLT code, "consolidate_blank" recursively calls
mlt_playlist_resize_clip
The bug is that sometimes in "mlt_playlist_resize_clip", the blank producer
seems to be disconnected from the playlist's blank (self->blank). Disconnected
means that they have a different length property.
So, in "mlt_playlist_resize_clip", when we have a blank producer, we get the
following for example:
mlt_producer_get_length( &self->blank ) returns 38000
and
mlt_producer_get_length( producer ) returns 15000
and I made sure they are the same producer using:
mlt_producer_cut_parent( producer ) == &self->blank
My guess is that for some reason the properties for "producer" and "self-
>blank" producer are not in sync, but maybe you have a better idea.
Then in "mlt_playlist_resize_clip", if we try to resize the producer to a
length of 17000. It only checks for the length of &self->blank, so setting the
out of producer to 17000 fails and we get an out of 15000 (the producer
length).
This results in playlist corruption since consolidate_blanks then changes the
duration of in between blanks.
Below is a patch that fixes the issue, but it would probably be better to
understand why the producer can give a length different than the playlist's
blank.
regards
jb
___________________________________________________________________________
diff --git a/src/framework/mlt_playlist.c b/src/framework/mlt_playlist.c
index 3f8f368..1974db2 100644
--- a/src/framework/mlt_playlist.c
+++ b/src/framework/mlt_playlist.c
@@ -928,6 +928,9 @@ int mlt_playlist_resize_clip( mlt_playlist self, int clip,
mlt_position in, mlt_
mlt_properties_set_int(
MLT_PRODUCER_PROPERTIES( producer ), "length", out - in + 1 );
mlt_producer_set_in_and_out( &self->blank, 0,
out - in );
}
+ else if ( out - in + 1 > mlt_producer_get_length(
producer ) ) {
+ mlt_properties_set_int(
MLT_PRODUCER_PROPERTIES( producer ), "length", out - in + 1 );
+ }
}
if ( in < 0 )
diff --git a/src/framework/mlt_playlist.c b/src/framework/mlt_playlist.c
index 3f8f368..1974db2 100644
--- a/src/framework/mlt_playlist.c
+++ b/src/framework/mlt_playlist.c
@@ -928,6 +928,9 @@ int mlt_playlist_resize_clip( mlt_playlist self, int clip, mlt_position in, mlt_
mlt_properties_set_int( MLT_PRODUCER_PROPERTIES( producer ), "length", out - in + 1 );
mlt_producer_set_in_and_out( &self->blank, 0, out - in );
}
+ else if ( out - in + 1 > mlt_producer_get_length( producer ) ) {
+ mlt_properties_set_int( MLT_PRODUCER_PROPERTIES( producer ), "length", out - in + 1 );
+ }
}
if ( in < 0 )
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