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Comment by Andrew_W | Hacker News Reader

Yeah, webm is already built in to ffmpeg, we just had a pretty limited focus for our initial release.

Even our mp4s aren't very well-optimized right now.

If you work with video a bit and think this tool might be helpful to you, let me know!

I record little screencasts/demos regularly for embedding them on webpages and currently always convert them with the ffmpeg CLI to WEBM, but it's really cumbersome and hard to remember all the command line flags you need to use (especially with 2 passes). I don't really like online cloud converters though because each video needs to both be uploaded and downloaded again and I'm worried they do a lossy compression on the video behind the scenes. A simple to use, trustworthy, client-based webapp to do this would be amazing.

That's awesome! Do you have an example ffmpeg command you run?

We're trying to keep this tool super simple for our end users, but I think we might be able to add a webm preset.

If you'd like me to look into it, drop me an email: andrew@<domain in link> and show me a sample command :)

I use the very basic:

    ffmpeg -i FILE -codec:v libvpx-vp9 -qscale:v 0 -codec:a libvorbis -qscale:a 0 FILE.webm

And end up with really good results out the other end. When I was rendering with pre-VP9 I needed a few more flags (stuff like crf) to maintain quality, but this works fine for most things. And has been really impressive on the filesize side of things.

I use this command I found on SO (was the first Google result): https://video.stackexchange.com/a/28276

    ffmpeg  -i input.mp4  -b:v 0  -crf 30  -pass 1  -an -f webm /dev/null
    ffmpeg  -i input.mp4  -b:v 0  -crf 30  -pass 2  output.webm

Making it two passes seems to be important for WEBM according to the post. It has worked well for me so far, but I need to look it up every time.

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