https://bugs.kde.org/show_bug.cgi?id=528442
Bug ID: 528442
Summary: Crash while trimming audio on timeline — invalid C++
tree state during MLT processing
Classification: Applications
Product: kdenlive
Version First 26.08.2
Reported In:
Platform: CachyOS
OS: Linux
Status: REPORTED
Severity: crash
Priority: NOR
Component: Timeline & Editing
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 198146
--> https://bugs.kde.org/attachment.cgi?id=198146&action=edit
gdb backtrace
# Kdenlive crashes while trimming audio on timeline — invalid C++ red-black
tree state during MLT audio processing
**Product:** Kdenlive
**Version:** 26.08.2
**Platform:** Linux
**Distribution:** CachyOS (Arch-based)
**Desktop:** KDE Plasma / Wayland
**Installed packages:**
- kdenlive 26.08.2-3.1
- mlt 7.42.0-1.1
## Description
Kdenlive crashed while I was trimming audio on the timeline.
The crashing thread was processing audio through MLT, including
`libmltnormalize.so`. An MLT event callback entered Kdenlive code, which
subsequently crashed inside `std::_Rb_tree_insert_and_rebalance()`.
GDB shows a null tree root (`__root = 0x0`) at `tree.cc:282`, suggesting an
invalid internal container state.
This may involve a threading or object-lifetime issue, although the exact root
cause is unknown.
## Steps to reproduce
1. Open a Kdenlive project containing audio clips.
2. Perform audio trimming operations on the timeline.
The crash occurred during this activity. Exact reproduction conditions have not
been established.
## Actual result
Kdenlive crashes and dumps core.
## Expected result
Audio trimming should work without crashing Kdenlive.
## Relevant backtrace
Crashing thread: LWP 140479
```text
#0 std::_Rb_tree_insert_and_rebalance()
at libstdc++-v3/src/c++98/tree.cc:282
__root = 0x0
#1 kdenlive + 0x666d87
#2 kdenlive + 0x66cd3e
#3 mlt_events_fire()
#4 mlt_properties_set_position()
#5 libmltnormalize.so
#6 mlt_frame_get_audio()
#7 libmltnormalize.so
#8 mlt_frame_get_audio()
```
The main GUI thread was also executing Qt Quick/QML code during a mouse-move
event.
Kdenlive-specific function names are unavailable because the corresponding
debug symbols were not resolved. The libstdc++ crash site was resolved using
debuginfod.
## Additional information
The complete GDB backtrace from `thread apply all bt full` is attached as
`kdenlive-backtrace.txt`.
The involvement of `libmltnormalize.so` in the stack does not necessarily
establish that the normalization filter caused the underlying corruption.
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