We present a watermarking algorithm to synchronously transmit Gong-Che notation musical scores and their musical instrument digital interface (MIDI) information. Our algorithm transforms the MIDI information into a binary sequence, which is used to form watermarking data. This watermark is embedded into the Gong-Che notation musical score image, using an inward clockwise rotation. The algorithm then uses optical music recognition to judge whether the musical information in the image is loss. Experiments have validated the effectiveness of our watermarking and expansion algorithms. The expansion process increases transmission accuracy, and the added processing time is minimal. Furthermore, our methodology can be applied to other musical notations such as conventional musical notation or numbered musical notation. 
Synchronous transmission of a Gong-Che notation musical score and its MIDI information