#11598: `gdigrab` Screen Capture Causes Cursor Flickering and Focus Loss on
Windows
(Multi-Monitor)
--------------------------------+--------------------------------------
Reporter: Evgene | Type: defect
Status: new | Priority: critical
Component: ffmpeg | Version: git-master
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 1
Analyzed by developer: 1 |
--------------------------------+--------------------------------------
**Environment**
- **OS**: Windows 11 Enterprise LTSC (Build 22000)
- **FFmpeg Version**: Custom build `N-119502-g12b853530a-20250515`
(`libavdevice 62.0.100`)
- **Hardware**: Multi-monitor setup, high-resolution displays
- **Reproducible**: Yes, with provided command
---
### **Steps to Reproduce**
0. **Version**
```
> ffmpeg -version
ffmpeg version N-119502-g12b853530a-20250515 Copyright (c) 2000-2025 the
FFmpeg developers
built with gcc 14.2.0 (crosstool-NG 1.27.0.18_7458341)
configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-
config=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64
--target-os=mingw32 --enable-gpl --enable-version3 --disable-debug
--enable-shared --disable-static --disable-w32threads --enable-pthreads
--enable-iconv --enable-zlib --enable-libfribidi --enable-gmp --enable-
libxml2 --enable-lzma --enable-fontconfig --enable-libharfbuzz --enable-
libfreetype --enable-libvorbis --enable-opencl --disable-libpulse
--enable-libvmaf --disable-libxcb --disable-xlib --enable-amf --enable-
libaom --enable-libaribb24 --enable-avisynth --enable-chromaprint
--enable-libdav1d --enable-libdavs2 --enable-libdvdread --enable-libdvdnav
--disable-libfdk-aac --enable-ffnvcodec --enable-cuda-llvm --enable-frei0r
--enable-libgme --enable-libkvazaar --enable-libaribcaption --enable-
libass --enable-libbluray --enable-libjxl --enable-libmp3lame --enable-
libopus --enable-librist --enable-libssh --enable-libtheora --enable-
libvpx --enable-libwebp --enable-libzmq --enable-lv2 --enable-libvpl
--enable-openal --enable-liboapv --enable-libopencore-amrnb --enable-
libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-
libopenmpt --enable-librav1e --enable-librubberband --enable-schannel
--enable-sdl2 --enable-libsnappy --enable-libsoxr --enable-libsrt
--enable-libsvtav1 --enable-libtwolame --enable-libuavs3d --disable-libdrm
--enable-vaapi --enable-libvidstab --enable-vulkan --enable-libshaderc
--enable-libplacebo --enable-libvvenc --enable-libx264 --enable-libx265
--enable-libxavs2 --enable-libxvid --enable-libzimg --enable-libzvbi
--extra-cflags=-DLIBTWOLAME_STATIC --extra-cxxflags= --extra-libs=-lgomp
--extra-ldflags=-pthread --extra-ldexeflags= --cc=x86_64-w64-mingw32-gcc
--cxx=x86_64-w64-mingw32-g++ --ar=x86_64-w64-mingw32-gcc-ar
--ranlib=x86_64-w64-mingw32-gcc-ranlib --nm=x86_64-w64-mingw32-gcc-nm
--extra-version=20250515
libavutil 60. 2.100 / 60. 2.100
libavcodec 62. 3.101 / 62. 3.101
libavformat 62. 0.102 / 62. 0.102
libavdevice 62. 0.100 / 62. 0.100
libavfilter 11. 0.100 / 11. 0.100
libswscale 9. 0.100 / 9. 0.100
libswresample 6. 0.100 / 6. 0.100
Exiting with exit code 0
```
```
> systeminfo | findstr /B /C:"OS Name" /B /C:"OS Version"
OS Name: Microsoft Windows 11 Enterprise LTSC
OS Version: 10.0.22000 N/A Build 22000
```
1. **Command**:
```shell
ffmpeg \
-loglevel level+info \
-y \
-framerate 10 \
-threads 4 \
-fflags nobuffer \
-avioflags direct \
-probesize 32 \
-analyzeduration 0 \
-f gdigrab \
-i desktop \
-map 0:v \
-f rawvideo \
-pix_fmt rgb24 \\.\pipe\ffmpeg_video
```
2. **Actions During Capture**:
- Move cursor rapidly across secondary monitor.
- Attempt to select text or drag UI elements (e.g., in a text editor).
3. **Result**:
- Visible cursor flickering.
- Intermittent loss of focus during interactions (e.g., text selection
resets).
---
### **Root Cause**
The `gdigrab` device in FFmpeg’s `avdevice` library forcibly repositions
the cursor during frame capture[^1]. On multi-monitor/high-DPI systems,
this introduces a race condition:
- FFmpeg moves the cursor to capture its position/sprite.
- Windows UI thread fails to restore the cursor quickly enough, causing
flickering and focus instability.
---
### **Workaround (Verified)**
**Patch `avdevice-62.dll`**:
Modify the library to **skip cursor repositioning** during capture.
Tools like x64dbg or Ghidra can be used to:
- Locate the cursor position update logic in `gdigrab`’s capture loop.
- NOP (disable) instructions that call `SetCursorPos()` or equivalent
Win32 APIs.
---
### **Proposed Upstream Fix**
1. **FFmpeg Code Change**:
In `libavdevice/gdigrab.c`, modify the cursor handling logic to:
```c
// Replace physical cursor movement with position caching
static void capture_cursor(...) {
// GetCursorPos(&cursor_pos); // <-- Remove this
// SetCursorPos(cursor_pos.x, cursor_pos.y); // <-- Remove this
// Draw cursor sprite on frame using cached position
}
```
2. **Alternative**: Modify `-draw_mouse 0` flag to avoid mouse
interaction.
---
### **References**
[^1]: [FFmpeg gdigrab Cursor Flicker Discussion
(2020)](https://stackoverflow.com/questions/34023630)
[^2]: [Previous conversation](https://ffmpeg.org/pipermail/ffmpeg-
devel/2019-December/255101.html)
--
Ticket URL: <https://trac.ffmpeg.org/ticket/11598>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker
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