How do I add a custom thumbnail to a .mp4 file using ffmpeg?

To use FFmpeg to add custom thumbnails to MP4 files, first, understand that the MP4 container format supports embedding cover images (typically as part of metadata), similar to how album covers are embedded in music files. You can accomplish this using FFmpeg's command-line tool. Below is a step-by-step guide:

Step 1: Prepare your MP4 video file and the thumbnail you want to embed. Ensure the thumbnail is in an appropriate format, such as JPEG or PNG.

Step 2: Open the command-line tool. On Windows, this could be Command Prompt or PowerShell; on Mac or Linux, it would be the Terminal.

Step 3: Use the following FFmpeg command to add the thumbnail to the video file as cover art:

bash
ffmpeg -i input_video.mp4 -i thumbnail.jpg -map 0 -map 1 -c copy -disposition:v:1 attached_pic output_video.mp4

The parameters in this command are explained as follows:

• -i input_video.mp4 specifies the input video file.
• -i thumbnail.jpg specifies the thumbnail file to embed as cover art.
• -map 0 indicates that all streams from the first input file (the video) will be mapped to the output.
• -map 1 indicates that streams from the second input file (the thumbnail) will also be mapped to the output.
• -c copy ensures streams are copied without re-encoding.
• -disposition:v:1 attached_pic sets the disposition of the second video stream (the thumbnail) to attached_pic, indicating it is cover art rather than a regular video stream.
• output_video.mp4 is the name of the output file.

Make sure to replace input_video.mp4 and thumbnail.jpg with your actual filenames, and output_video.mp4 with your desired output filename. If your video or thumbnail file is in a different directory, provide the correct file paths.

Step 4: Run this command and wait for FFmpeg to process the file. Upon completion, you should have an output video file containing the custom cover image.

Note: FFmpeg is a powerful tool with many options and features. The above command is a basic example; you may need to adjust it based on your specific requirements. If your video or thumbnail requires specific encoding settings, add additional parameters to modify the video and audio encoder options.