Adding a Watermark to Videos with Fluent FFMpeg: A Guide to Complex Filtering

When working with videos, adding a watermark is a common task that requires precise control over the filtering process. In this article, we'll explore how to add a watermark to videos using Fluent FFMPEG, a Node.js library for batch video processing. We'll also address a common issue where multiple filter options cannot be used together.

The Problem with Combining Filter Options

When working with Fluent FFMpeg, you may have encountered the following error message: 'Filtergraph 'crop=in_w-2*150:in_h,pad=980:980:x=0:y=0:color=black,subtitles=subtitles.ass' was specified through the -vf/-af/-filter option for output stream 0:0, which is fed from a complete.' This error occurs when trying to use multiple filter options simultaneously, such as video filters (-vf) and complex filters (-filter_complex).

To resolve this issue, you need to understand that Fluent FFMpeg's filter options are mutually exclusive. You can only use one type of filter option per stream. In the case of adding a watermark, we'll need to use the -filter_complex option.

Adding a Watermark with Complex Filtering

The -filter_complex option allows you to create complex filtering pipelines using a text-based syntax. To add a watermark to your video, you can use the following command:

```

ffmpeg -i input.mp4 -i watermark.png -filter_complex ''0''1'overlay=10:10' output.mp4

```

In this example, we're adding an overlay filter that combines two inputs: the original video (input.mp4) and a watermark image (watermark.png). The overlay is positioned 10 pixels from the top-left corner of the screen.

To further customize your filtering process, you can use various filter options within the complex filter string. For example, to resize the watermark image before overlaying it, you can add the scale filter:

```

ffmpeg -i input.mp4 -i watermark.png -filter_complex ''0''1'scale=-2:ih*0.1'watermark';'0''watermark'overlay=10:10' output.mp4

```

In this example, the scale filter resizes the watermark image to 10% of its original height.

Adding a watermark to videos using Fluent FFMpeg requires careful consideration of filter options and complex filtering pipelines. By understanding the limitations of multiple filter options and using the -filter_complex option, you can create sophisticated video processing workflows that meet your specific needs. Whether you're looking to add subtitles, crop or pad video content, or overlay images, Fluent FFMpeg provides a powerful toolset for batch video processing.

Fluent ffmpeg add watermark