First of all, you should check whether your DVD disc is scratched or damaged. If the disc is damaged, HandBrake may not recognize the DVD correctly, which can result in an incomplete rip.
If the disc is in good condition, the most likely causes of HandBrake doesn't convert whole movie are overloaded CPU and DVD copy protection.
1. Overloaded CPU
DVD ripping is a CPU-intensive process. If your computer is under heavy load, HandBrake may run slowly or stop abruptly while ripping. You can fix it by reducing CPU usage, such as closing unnecessary programs and disabling resource-intensive processes running in the background.
On Windows:
Press Ctrl + Shift + Esc to open Task Manager. Look for processes consuming significant CPU or memory. Identify the app or process that you don't need, right-click on it and select End Task.
On macOS:
Open Activity Monitor from Applications. Identify processes using high CPU and close unnecessary ones.
2. DVD copy protection
Most DVDs, if not self-made, come with copy protection. But HandBrake says explicitly "HandBrake does not defeat or circumvent copy protection of any kind", so it won't rip the DVD correctly.
To fix this, you can try installing Libdvdcss for HandBrake to rip some CSS-encrypted DVDs. Below is a generic workflow:
Step 1: Download the corresponding libdvdcss library on your Windows.
32-bit libdvdcss | 64-bit libdvdcss
Step 2: Copy the .dll file to your HandBrake installation folder. The default location is C:\Program Files\Handbrake unless you customized a new path during the setup process.
Step 3: Restart your computer and launch your HandBrake. Now, try ripping your DVD and see if it works.
Note that libdvdcss can only help HandBrake decode DVD CSS encryption, but it does not support all types of DVD protection. If your DVD uses other copy protection methods, HandBrake might still fail to rip the entire movie.
In such cases, it's far beyond the capabilities of HandBrake, and you need a DVD ripping tool with broader DVD protection support, like WonderFox DVD Ripper Pro.