video and audio formats supported by all browsers

There is a way to be supported by all browsers, desktop and mobile. For give two sources: first is a WMV, and second one is MP4. But... reconverted (from MP4, AVI, etc) to MP4 with Handbrake. Yes, from MP4 to MP4. Some ways of packing data into MP4 are not supported by ALL browsers (like in FormatFactory- but still, it's a great tool). It's universal and is working everywhere.

As for audio- use MP3 and M4A sources for . Some releases of Internet Explorer won't play M4A if it was converted from single-channel MP3, so make sure it's stereo.

According to the tables from the MDN link we can see that these formats are common:

Desktop

Mobile

Conclusion

In conclusion you are pretty safe on the video side using H.264 via the MP4 container using MP3/AAC for audio. For just audio MP3 seem to be supported across all browsers.

For audio on mobile side you have a little more challenges since not all formats seem to supported by all browsers by the time this table was made. You may have to add special treatment depending on platform and capabilities.

There is anyways the FFMPEG which on server side can convert to and from almost any video and audio format which would allow you to upload many different formats - but, it involves a server which you must be able to customize for this purpose.