Knowledge Base

Problem

After running an acquisition, recorded video files are saved as 0 KB (or appear corrupt/empty) and cannot be opened in EthoVision or other media players. Tracking data may be captured normally, but the media file is unusable. In some cases there is also a significant delay (10–60+ seconds) between pressing Start Acquisition and recording actually beginning.

Details

Caused by incompatible NVIDIA GPU drivers (often installed automatically via Windows Update, the NVIDIA App, or other update utilities) conflicting with the LEADTOOLS codec library used by EthoVision for video encoding. Affects EthoVision XT 18 and 19 on systems with NVIDIA 10, 20, 30, 40, and 50 series GPUs. A permanent fix was included in EthoVision XT 19.0.1914 and later builds (e.g., 19.0.1916). Earlier versions require a workaround.

Solution

**Immediate workaround (no driver change required):**
1. Open EthoVision and go to **File > Preferences > Video settings**.
2. Set **'Play back and record video with'** to **CPU**.
3. Restart EthoVision.
4. Run a short test acquisition to confirm videos save and open correctly. Video quality and tracking accuracy are unaffected.

**Driver rollback workaround:**
1. Uninstall the current NVIDIA driver via **Add/Remove Programs**.
2. Download and install NVIDIA driver **581.57** from https://www.nvidia.com/en-us/drivers/details/257329/ (or driver **580.88** from https://www.nvidia.com/en-us/drivers/details/251353/ as an alternative).
3. During installation, choose **Custom (Advanced)** and select **Perform a clean installation**. Install only the Graphics Driver and HD Audio Driver; disable the NVIDIA App and other bundleware.
4. After installation, you may switch EthoVision preferences back to GPU.

**Permanent fix (recommended):**
1. Upgrade to **EthoVision XT 19.0.1914 or later** (e.g., 19.0.1916), which resolves the driver incompatibility natively.
2. Download the installer from MyNoldus or request a direct download link from support.

**Preventing recurrence:** Ask your IT department to disable automatic NVIDIA driver updates to prevent the issue from returning.