when sending a video on whatsapp for example, whatsapp converts the video beforehand so videos taken from the smartphone camera are not too big to send. I wonder if there are any guides / best practices related to api.video to achieve the same?
We don’t provide such guide but I can give you few hints.
Also, you have to keep in mind that doing so will alter the video quality.
If your application includes a video recorder, you can lower the video (and audio) bitrate, the resolution, the frame rate of the recorder.
If the users pick the videos from their gallery, you can transcode them with a lower the video (and audio) bitrate, the resolution and the frame rate.
For an iOS implementation, I would recommend to read Exporting video to alternative formats | Apple Developer Documentation and for Android, you could directly use LiTr.
Also, to improve the ingestion, you should have a look at Video best practices · api.video documentation.