Recently I learned that VP9 video can be re-containerised to something other than webm, without re-encoding the original video and/or audio. This is useful for importing into tools that support the VP9 codec, but not the webm container.
Recent versions of
ffmpeg(1) have a
-c copy shorthand for instructing the audio and video encoders to just copy the source:
$ ffmpeg -i example.webm -c copy example.mp4
Note that you’ll get an error if you try to output to a mov container, as I’ve seen plenty of bloggers and forum posts erroneously suggest:
[mov @ 0xHEX] vp9 only supported in MP4
ffmpeg can also re-containerise into my preferred Matroska, which I’ve also since learned is the format on which webm is based:
$ ffmpeg -i example.webm -c copy example.mkv
Tools like DaVinci Resolve can now import your VP9 video, albeit with variable results. You may need to re-encode entirely if the output is garbled.
$ ffmpeg -i example.webm example.h264.mp4