What is a MIDI audio track and what format is MIDI

Only one channel can be set for a track, and different tracks can use the same channel, but no matter how you insert the timbre-changing information, the same tone will be produced at the same time by the same channel.

Added: Regarding the problem of the length of the MIDI file, in some cases you said so, but the end of the MIDI file ** is actually the end of the last MIDI message, for example, there is a 1-minute song, I insert a timbre change message at the 2-minute position, but there is actually no note here, the song ** has no sound after 1 minute, but it will be stopped again until ** 2 minutes here.

Generally speaking, when doing MIDI, it is done in multiple tracks, even if some tracks with the same timbre will be done separately, for example, the piano can be divided into left and right hands, and the strings can be divided into four harmonies, which involves the problem that different tracks can be set to the same channel and use the same timbre as mentioned above.

Different tracks are different instruments. ^

The most basic output of MIDI is probably directly corresponding to Microsoft's wavetable.。。 with different tones.

The sound source is the same.

I don't know what you mean by channel.

MIDI is a command for a machine to play. (For example, the first note "Do" is a 4th note, and the playing speed is recorded).

It can't produce any sound on its own, and needs to be played with a variety of sound sources (hard sources, soft sources).

It's like a person watching a score and playing a piano, this person is the computer, the score is MIDI, and the piano is the sound source.

Multiple track MIDI files are equivalent to a total score for playing a symphony, and the computer assigns it to the corresponding source (of course, you can also specify it), similar to an orchestra playing, the trumpet to see the trumpet line, the violin to the violin line, and combine them to play together.

MIDI files are binary files.

This type of file generally has the following basic structure: File Header Data DescriptionThe file header generally includes the type of file, because the MIDI file is only in the form of . There are two types of MID as the extension: Class 0 and Class 1, and the format of the familiar bit** piece is much more mountainous, so there will be such a thing as a file header.

Unlike waveform files, MIDI files do not sample, but record each note of ** as a number, so compared with waveform files, the leakage file is much smaller, which can meet the needs of long-term **. The MIDI standard specifies the mixing and pronunciation of the various tones, and the numbers can be resynthesized into ** by means of an output device.

The main limitation of MIDI** is that it lacks the ability to reproduce real, natural sounds, so it cannot be used in situations where voice is required. In addition, MIDI can only record a limited number of combinations of instruments as specified in the standard, and playback quality is limited by the sound card's return-width synthesis chip. In recent years, foreign popular sound cards have generally used the wavetable method for synthesis, which has greatly improved the quality of MIDI.

Composition of MIDI format:

MIDI data is made up of several identically formatted sub-data that record all the information of a track in a multi-track format. To add an extra track, simply append the data to the end of the previous track, but don't forget to change the nnnn (number of tracks) in the file header.

Let's start with the global audio track. Global audio tracks include additional information about the song (such as title and copyright), song tempo, and system code (sysx). Both global tracks and tracks with notes start with "4d54726b", which is actually the ASCII character "mtrk", followed by a 4-byte integer that indicates the number of bytes of the track, not including the first 4 bytes and the 4 bytes itself.

We can understand this in the following examples.

Then there's where the data is recorded, and each data has the same structure: the time difference event. The so-called time difference refers to the number of times from the previous event to the event, and its unit is tick (the smallest time unit of MIDI).

Its composition is quite special, and it should be explained here in binary.

The above content reference: Encyclopedia-MIDI