enhancement: convert the mp3 files to midi files and play them dynamically

[SleepyLGod]

What's changed and what's your intention?

^{Originally posted by Haodong Lu October 8, 2022}

The total idea is changed and expanded from only developing a midi player to developing a converter as well as a 3d player of midi pieces for several kinds of instruments.

Checklist

Firstly, this issue can be divided into two parts:

• a *.midi file generator；
• a *.midi file parser.

Details:

• Convert mp3 files to standard midi files.
• Convert songs and pieces in other formats like wav to standard midi files.
• Choose and upload local files freely.
• Play all kinds of standard midi files in the web page simply.
• Change the song tempo in the simple player.
• Play midi files(piano pieces) in the web page dynamically.
• Change the song tempo in the dynamic player.
• Play midi files of various musical instruments in the web page dynamically.
• Modify the converting and transmitting speed.

Refer to a related PR, issue, or discussion link (optional)

Discussed in #3
#18 #17

[SleepyLGod]

Well, considering the terrible way we display the midi files we've got, we decided to modify the web page using three.js and MIDI.js, making a 3D instruments web player. And now we decided to play piano pieces as the first try!