Impossible to add metadata with an ffmetadata file

[avibrazil]

Documentation teaches how to embed metadata using an FFMETADATA file as input. Its basically ffmpeg -i INPUT -i FFMETADATAFILE -map_metadata 1 -codec copy OUTPUT

On ffmpeg-python would be like this:

                original  = ffmpeg.input("file.mov")
                metadata  = ffmpeg.input("file.ffmetadata")
                    muxer=ffmpeg.output(
                            original,
                            metadata,
                            "output.mov",
                            acodec='copy',
                            vcodec='copy',
                            movflags='faststart+use_metadata_tags',
                            map_metadata=1,
                            **ffmpegFlags
                    )

But this will fail because ffmpeg-python will add a -map 1 parameter here for the ffmetadata input. FFmpeg will complain and fail because input #1 doesn't have streams.

To fix this, ffmpeg-python must not add a -map 1 parameter if input is an FFMETADATA text file. These files must have .ffmetadata extension in order to ffmpeg command to recognize their format, so ffmpeg-python should decide to not add -map 1 based on such file name.

Meanwhile I would appreciate some advice on how to overcome current limitation and use ffmetadata files somehow.

Thank you in advance.