Which format is better for compressing small files: WebM or MP4?

For broader compatibility, I’d recommend MP4. While both can hold different types of video compression, MP4 tends to be more widely supported. Consider using a high-compression codec like H.265/HEVC, and adjust the resolution and bitrate to keep the file size manageable while maintaining quality.

When it comes to WebM and MP4, both are just container formats. The actual size of your file is mostly determined by the bitrate and encoding options you choose, like AV1, H.264, or H.265. Generally, more advanced codecs like AV1 and H.265 can help maintain better quality while keeping the file size down.

Why not try both formats and compare the results? You might find one works better for specific content than the other.

Honestly, both formats are just containers, so it really depends on what codecs you use. You might want to experiment with both to see which works best for your needs, especially with the settings you're using.

It ultimately depends on a few factors: the video's length, resolution, and your target file size. If you can, try writing a small script that compresses the video using various options for each format. Start with the smallest output files and check their quality until you find a balance that works for you. In my experience archiving videos, I've been able to reduce file sizes significantly with some trial and error.