How am I supposed to set GPU memory in RPi4?

Question

I have been using RPi4 for a while and I have found some problems playing videos on VLC and YouTube. After searching for a long time, I found that these problems can be solved by increasing GPU memory. I found that option in the Raspberry Pi configuration I need to know ,

1. What is the maximum and minimum memory value for GPU?
2. What is the optimum value of GPU memory?
3. Will I face any problems if I set the value very high or very low?

Answer 1

Here's the relevant part of the official docs.

Min and max:

GPU memory in megabytes, sets the memory split between the CPU and GPU; the CPU gets the remaining memory. The minimum value is 16; the technical maximum value 944 [for the RPi 4]. The default value is 64, values above 512 will not provide increased performance and should not be used.

Default values:

For Pis with less than 1GB of memory, the default is 64; for Pis with 1GB or more of memory the default is 76.

Recommended value:

The Raspberry Pi 4 3D system has it's own Memory Mangement Unit (MMU) so textures and other GL resources are not allocated from the gpu_mem but Linux system memory instead. This means that gpu_mem can be set to a lower value, so even if you are using the H264 and camera then 128MB will probably be enough.

Answer 2

You shouldn't need to set it beyond the default value in the plain Raspbian /boot/config.txt. Max value is 128M.

Setting it beyond 128M can leave your Raspberry Pi 4B unbootable.

GPU memory on a RPi4B isn't used in the same way as on earlier Raspberries.