Please allow injecting into the existing video file instead of copying it.

[Boscop]

https://github.com/google/spatial-media/tree/master/spatialmedia#inject

Saves a version of injected with spatial media metadata to . and must not be the same file.

Please allow using the same file for both. (Injecting into the existing file.)
This would be very useful for working with huge video files, especially when the input video file would be useless without the metadata anyway and would be deleted right after.