An interesting library, but not working

[Garik-]

I tried decoding and encoding the file twice. Second decoding produces an error error parsing TimeSignature - unexpected data content (0). After I compared the source and the resulting file in vimdiff. They are different :(

func TestDecodeAndEncodeFile(t *testing.T) {
	f, err := os.OpenFile("./remove/test.mid", os.O_RDWR, os.ModeAppend)
	if err != nil {
		t.Fatal(err)
	}
	defer f.Close()

	decoder := NewDecoder(f)
	decoder.Debug = true
	err = decoder.Decode()
	if err != nil {
		t.Fatal(err)
	}
	
	encoder := NewEncoder(f, decoder.Format, decoder.TicksPerQuarterNote)
	encoder.TimeFormat = decoder.TimeFormat

	for _, src := range decoder.Tracks {
		dst := encoder.NewTrack()
		dst.SetName(src.Name())
		dst.Events = src.Events
		dst.Size = src.Size
	}

	encoder.NumTracks = decoder.NumTracks

	f.Seek(0,0)
	encoder.Write()
}