How to Concatenate Videos Using FFmpeg

Video editing is a crucial aspect of creating content for many people. Whether you're a YouTuber, a marketer, or just someone who wants to share videos with friends and family, being able to edit and manipulate your videos is key. One of the most basic video editing tasks is concatenating videos, which combines multiple files to create one cohesive video.

FFmpeg is a powerful tool that allows you to do just that, and in this guide, we'll walk you through the process of FFmpeg concatenate videos. Whether a beginner or an experienced video editor, this guide will provide you with all the information you need to seamlessly merge your videos. From installation to execution, we'll cover it all so you can streamline your video editing process.

Overview and Installation of FFmpeg

FFmpeg is free, open-source project that allows you to record, convert, and stream digital audio and video. It is a command-line tool widely used in video editing and transcoding. FFmpeg can be used to concatenate videos and other tasks, such as adding subtitles, changing video resolution, and more. It is available for Windows, Mac, and Linux, making it a versatile and accessible tool for anyone to use.

Here's how to install FFmpeg:

Step1 Log in to your Ubuntu server via SSH and update the package index.

$ sudo apt update

Step2 Install FFmpeg and all the required dependencies

$ sudo apt install ffmpeg

Step3 Verify the version of FFmpeg that you've installed.

$ ffmpeg -version

Prerequisite

Before we merge videos using FFmpeg, we must understand the various methods available to us. FFmpeg offers three ways to concatenate videos: a demuxer, a filter, or a protocol. However, each method has its own set of considerations, and the best method for you will depend on the properties of the videos you're working with.

It's crucial to ensure that all encoding-related properties align with your chosen method. This includes the timebase, height and width, codecs, and pixel format. Some methods require the videos you're merging to have the same encoding, while others allow for different encodings. It's essential to keep this in mind to ensure that the final video is seamless without any breaks. Remember that these prerequisites will help you have a smooth process.

Concatenate Videos With Same Codecs Using FFmpeg

If the videos you want to concatenate have the same codec, you can use the FFmpeg "concat" demuxer or protocol to join them together. This simple and efficient method doesn't require re-encoding the videos, saving time and preserving the original quality. This section will review the steps to concatenate videos using the "concat" demuxer and "concat" protocols in FFmpeg.

Merge Videos With the "Concat" Demuxer

The concat demuxer in FFmpeg allows you to join together multiple video files with the same codecs by reading a list of file paths from a text file and demuxing them in sequence. Each video starts where the previous one finishes without needing to re-encode the videos. Here's how to do it:

Step1 Create a  .txt file and list the paths of the video files you want to merge.

Join_video.txt

file /Users/Video/input1.mp4

file /Users/Video/input2.mp4

Note: You can add more than two video files.

Step2 Run the FFmpeg command:

ffmpeg -f concat -safe 0 -i join_video.txt -c copy output_demuxer.mp4

Note: -safe 0 is added to accept any file name.

-c copy will copy all the streams.

As this method allows you to "stream copy" the files instead of re-encoding them, the concatenation is very fast. This can be a good option if you have videos with the same codecs and want to join them quickly without losing quality.

Join Videos With the "Concat" Protocol

The concat protocol in FFmpeg allows you to join together multiple video files in a specific format that supports file-level concatenation, such as MPEG-2 TS. However, it cannot be used for other video formats like MP4 and WEBM.

Here's how to use the "concat protocol:

Step1 Run the FFmpeg command:

ffmpeg -i "concat:input1.ts|input2.ts" -c copy output_protocol.ts

Note: The concat protocol allows you to "stream copy" the files by adding the option -c copy.

Step2 Input the file name of the video using this code:

ffmpeg -i "concat:input1.mp4|input2.mp4" -c copy output_protocol.mp4

Note: If you try to use this method on video formats that are not supported, only the first input video will be saved in the output video. And the video ends after the first video.

Although this method is limited in terms of supported video formats, it's very easy to use if you merge videos in the supported formats. It's a single command in the terminal without needing a text file. Additionally, using the -c copy option makes it efficient as it doesn’t require re-encoding, saving time.

Concatenate MP4 Video Files of Different Codecs & Resolutions Using FFmpeg

If the videos you want to concatenate have different codecs or resolutions, you can still use FFmpeg to join them together. However, this method requires re-encoding the videos, which can take longer and may result in a loss of quality. This section will cover the steps to concatenate videos with different codecs or resolutions using FFmpeg.

Here's how to do it:

Step1 Provide the names of the input files to FFmpeg.

ffmpeg -i file1.mp4 -i file2.mp4 -i file3.mp4 \

Step2 Use the filter_complex filtergraph parameter to instruct FFmpeg from where to take the audio and video.

-filter_complex "[0:v] [0:a] [1:v] [1:a] [2:v] [2:a]

Note: [0:v][0:a] means FFmpeg needs to take the video and audio from the 0th video (file1.mp4).

Step3 Tell FFmpeg to concatenate three files (n=3).

concat=n=3:v=1:a=1 [vv] [aa]" \

Note: The v=1:a=1 implies one stream for the audio and one stream for the video.

Step4 Map these audio and video outputs to the final video container. This is done as follows:

-map "[vv]" -map "[aa]" mergedVideo.mp4

It is important to note that this method requires re-encoding the videos, which can take more time and may result in a loss of quality. However, it offers the flexibility of filtering the videos before concatenating them. The filter_complex method in FFmpeg allows you to concatenate videos of different codecs and resolutions. The final step is to map the audio and video outputs to the final video container. This can be done using the -map command.

Concatenate Videos With Multiple Audio Streams Using FFmpeg

Concatenating videos with multiple audio streams can be more complex than concatenating videos with a single audio stream. This section will cover the steps to concatenate videos with multiple audio streams using FFmpeg. We'll be using the filter_complex method in FFmpeg, which allows you to manipulate and concatenate multiple audio and video streams in a single command. This method is more advanced but allows you to join videos with different audio streams and create a final video with multiple audio tracks.

Step1 Specify the input files and opening.mkv, episode.mkv, and ending.mkv:

$ ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex

Step2 Use the filter_complex parameter in FFmpeg to specify the input streams for the video and audio.

[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]

Note: Single video stream ([0:0], [1:0], [2:0])

Dual audio streams ([0:1][0:2], [1:1][1:2], [2:1][2:2])

Step3 Use the concat filter to specify that you want to concatenate 3 files (n=3) with 1 video stream (v=1) and 2 audio streams (a=2). Specify the output streams as [v], [a1], [a2]:

concat=n=3:v=1:a=2 [v] [a1] [a2]

Step4 Use the -map option to map the output streams to the final video container:

-map '[v]' -map '[a1]' -map '[a2]' output.mkv

[Bonus] Join Videos Together With Filmora

While FFmpeg offers a wide range of options for joining videos together, it can have a steep learning curve for some users. An alternative method for joining videos is using Filmora. Wondershare Filmora is a user-friendly video editing software that allows you to easily join multiple videos. It's a great option for users new to video editing or needing experience with command-line tools like FFmpeg.

Filmora has a simple drag-and-drop interface, making adding, arranging, and editing videos and audio tracks easy. Additionally, it offers various features like split, trim, crop, merge, and more. It also has various effects, transitions, and animations to enhance the overall look of your video. With Filmora, you can create professional-looking videos with minimal effort.

How-to Steps

Here’s how to merge videos using Filmora:

Step1 Open Filmora and click "New Project."

Step2 Go to "File" > "Import Media" > "Import Media Files" to add your video files to the media library.

Step3 Drag and drop the files you want to merge from the media library to the timeline, and then you'll get the merged video seamlessly.

Step4 Edit your video.

Step5 After editing, click the "Export" tab to save your videos.

Conclusion

FFmpeg is a powerful tool that allows you to concatenate videos in various ways. Whether you're working with videos of the same codecs and resolutions or videos with multiple audio streams, FFmpeg can handle it. However, for users new to video editing or needing experience with command-line tools, using Filmora can be a more user-friendly option. It offers a simple drag-and-drop interface and a variety of features and effects to enhance the overall look of your video.