How to Add repeated background audio with ffmpeg

When using FFmpeg to add repeating background audio, there are two main steps to follow: ensuring the background audio loops long enough to cover the entire video, and merging the looped audio with the video file. Below are the specific steps:

Step 1: Prepare the Audio File

First, ensure you have a background audio file suitable for looping. This means the audio should have smooth transitions at the beginning and end to sound seamless when repeated.

Step 2: Loop the Audio

Using FFmpeg's concat filter or command, you can create a sufficiently long audio file to cover the entire video length. The following FFmpeg command can be used:

bash
ffmpeg -stream_loop -1 -i background.mp3 -c copy -t 3600 long_background.mp3

Here, -stream_loop -1 indicates infinite looping of the audio (until the desired length is reached), -i background.mp3 is the input file, -t 3600 specifies the total output audio length in seconds (here, one hour as an example), and long_background.mp3 is the output file name.

Step 3: Merge Video and Audio

Once you have the sufficiently long background audio, the next step is to merge this audio into the video file. The following command can be used:

bash
ffmpeg -i video.mp4 -i long_background.mp3 -c:v copy -c:a aac -strict experimental -map 0:v:0 -map 1:a:0 output.mp4

Here, -i video.mp4 and -i long_background.mp3 are the video file and long audio file, respectively. -c:v copy and -c:a aac specify that the video codec is copied and the audio codec is converted to AAC. -map 0:v:0 -map 1:a:0 ensures the video comes from the first input file and the audio from the second input file. output.mp4 is the output file name.

Example Practice

Suppose you have a 2-minute video (video.mp4) and a 1-minute music file (background.mp3), and you want this music to play repeatedly throughout the video. You can follow the above steps to first generate a sufficiently long audio file using the command, then merge it with the video.

The above steps can help you add repeating background music when using FFmpeg, applicable to various video and background music combinations.