PickedMedia

A picked clip, as both the file the dialog returned and the source an export reads it through.

A MediaSource carries no display name, and on a browser its object URL is not a handle on the picked file, so the picker hands both back. Reading the file's name goes through the content resolver on Android, so read it once in the callback and hold the result rather than reading it during composition.

In a browser source is an object URL that lives until the page unloads. MediaSource.release frees it earlier, once nothing reads the source any more.