Screen recording apps allow users to select the framerate for a recording and generally, they do not have any trouble recording at that rate. If it’s a low framerate e.g., 25 or 30, it is highly unlikely that the framerate will drop. That said, it can still happen. This normally happens when you’re recording something that is taking a toll on your GPU e.g., you’re playing a game and recording the gameplay, your GPU may try and give you a higher FPS in your game but limit it in the recording. If you suspect the framerate for a video dropped at some point while you were recording it, you can use FFMPEG to check it.
FFMPEG is a command-line tool and there isn’t much that goes into installing it. If you use it often, it’s a good idea to add it the PATH. We have the whole process covered here and it won’t take more than ten minutes to set it up for use.
Check for variable framerate
Open File Explorer and navigate to the folder that contains the video you want to check the framerate for. In the location bar, enter ‘cmd’, and tap the Enter key.
This will open a Command Prompt window that is pointed at that folder. You can now run the following command to check the variation in the framerate. Make sure you change video_Name.mp4 to the actual name and extension of the video.
ffmpeg -i video_Name.mp4 -vf vfrdet -f null -
ffmpeg -i DASH_720.mp4 -vf vfrdet -f null -
As for the results, they won’t be in whole numbers telling you if the frame rate dropped from 25 to 15 at some point. Instead, you’re going to see a VFR value which is going to tell you if there is any variance. If the value is 0.000, upto the number of supported decimal points, there is no frame rate variance in the video.
If it isn’t zero, then you have some variance in the framerate but it won’t tell you which parts of the video have a lower or higher framerate. Instead, you will see something like the information below.
[Parsed_vfrdet_0 @ 0x56518fa3f380] VFR:0.400005 (15185/22777) min: 1801 max: 3604)
The 0.400005 indicates that about 40% of the video has a variable framerate. The number that follows it is the number of frames with a variable rate (15185) and the number with a stable rate (22777). Together, they will make up the total frames in the video.
A variation in the framerate isn’t always easy to spot and if you can’t tell visually where the frame rate in a video drops, you can try splitting it into smaller segments and running the command on each segment to see which one has the variance.