How to restrict ffmpeg to use only 50% of my CPU?

In Linux systems, you can use the nice and cpulimit tools to limit the CPU resources consumed by the ffmpeg process. There are two primary methods to achieve this:

Method 1: Adjusting Process Priority with nice

nice is a program that adjusts process priority by modifying the scheduling priority of the process. By increasing the priority of other processes (while lowering ffmpeg's priority), you can make the ffmpeg process more cooperative, allowing it to consume more than 50% of the CPU when the system is idle, but it will yield CPU to other high-priority processes when the system is busy.

bash
nice -n 10 ffmpeg [ffmpeg parameters]

• -n 10 sets a 'niceness' value, which ranges from -20 (highest priority) to 19 (lowest priority). Here, I use 10 as an example, which lowers ffmpeg's CPU priority, allowing other processes more opportunities to utilize CPU resources.

Method 2: Limiting CPU Usage Rate with cpulimit

cpulimit is a tool that restricts the CPU usage rate of a process. Unlike nice, cpulimit can directly control the CPU usage rate to not exceed a specified percentage.

First, install cpulimit (if not already installed):

bash
sudo apt-get install cpulimit  # Debian/Ubuntu systems
sudo yum install cpulimit      # RedHat/CentOS systems

Then, you can limit ffmpeg's CPU usage rate after starting it with:

bash
cpulimit -l 50 -p $(pidof ffmpeg)

Alternatively, start ffmpeg and limit its CPU usage rate in a single command:

bash
cpulimit -l 50 -- ffmpeg [ffmpeg parameters]

• -l 50 specifies the CPU usage limit, set here to 50%, meaning the ffmpeg process can use at most 50% of the total CPU resources.
• -p is followed by the process ID (you can obtain the ffmpeg process ID using pidof ffmpeg).

In summary, nice indirectly affects CPU usage by adjusting priority, while cpulimit can more directly limit the CPU usage percentage. Depending on your specific needs, you can choose the appropriate tool for resource management. In production environments, it may also be necessary to combine process monitoring and automation scripts for more effective resource management.