It took me a while but I've worked out that Firefox support of Flac files is limited to where the ID3 Tag is.
If the ID3 tag is infront of the Flac Audio Frames then Firefox simply cannot play it.
Files with the 4 byte header: fLaC are supported.
Flac files with the Header: ID3 are UN - supported
These files that start the music frames after the ID3 Tag are NOT supported by Firefox and cause unsupported stream error in Emby)
Is it possible to detect the requesting client - ie Firefox , check the Header and automatically transcode the unsupported file types to a supported type?
Is it possible that Emby reporting to Firefox that the File is not a Flac file?? - I think the former - not supported as they play in MS Edge
Edited by mickle026, 15 March 2019 - 08:45 PM.