Change Video Frame Rate#

How to change the frame rate of a video from 24 fps to 30 fps.

Source Video#

For a source video we use the MP4 file from the TED talk video What’s the next window into our universe? by Andrew Connolly. The original video format is Wide 480p or 16:9, 854 x 480.

Complete Program#

This code takes an MP4 file encoded at 24 fps, and increases the video framerate to 30 fps. The audio stream is copied from the source as is.

using PrimoSoftware.AVBlocks;
using System.Collections.Generic;

namespace ChangeVideoFrameRate
    class Program
        static void Main(string[] args)

            // start with two identical input and output configuration
            var inputInfo = new MediaInfo() {
                InputFile = "AndrewConnolly_2014.mp4"

            var outputInfo = new MediaInfo() {
                InputFile = "AndrewConnolly_2014.mp4"

            if (inputInfo.Load() && outputInfo.Load()) {
                // create input socket
                var inputSocket = MediaSocket.FromMediaInfo(inputInfo);

                // create output socket
                var outputSocket = MediaSocket.FromMediaInfo(outputInfo);
                outputSocket.File = "AndrewConnolly_2014_30fps.mp4";

                // change the frame rate from 24 fps to 30 fps
                var outVideoStream = outputSocket.Pins[0].StreamInfo as VideoStreamInfo;
                outVideoStream.FrameRate = 30.0;

                // create and run a transcoder
                using (var transcoder = new Transcoder()) {

                    // process
                    if (transcoder.Open())


How to run#

Follow the steps to create a C# console application in Visual Studio but in Program.cs use the code from this article.

Download the AndrewConnolly_2014.mp4 MPEG4 file from the Internet Archive and save it in bin/x64/Debug/net6.0 under the project’s directory.

Run the application in Visual Studio. Wait a few seconds for the Transcoder to finish. The converted file AndrewConnolly_2014_30fps.mp4 will be in the bin/x64/Debug/net6.0 directory.