[Question / Help] WebM & OGV export example + multi-threading?

Hi, I'm very new to ffmpeg but was able to reference some examples in the issues to successfully generate a `mp4` video like so:

```
ffmpeg.run('-framerate', '30', '-i', 'output-%d.png', '-s', '1280x720', '-c:v', 'libx264', '-pix_fmt', 'yuv420p', 'out.mp4')
```

May I learn how to do the same for `WebM/libvpx` and `ogv/theora`?

Additionally, I understand I can pass `-row-mt 1` into the `run` command for faster `webm` export, but for `ogv` exports am I to correctly understand they're strictly single-threaded?

Thank you.