Stuck at midiToSequenceProto when attempting to decode large MIDI files

[ruochenjia]

My node.js app is stuck at the midiToSequenceProto call when decoding a large MIDI file (attached here). This should not happen as other media players such as VLC takes less than 1 second to start playing. I think it should be possible to only load a part of it instead of loading all at once, but magenta.js does not seen to provide a way of doing so.