How to implement music device communication through PHP and MIDI protocol

How to achieve music device communication through PHP and MIDI protocol

With the development of music technology, more and more music devices begin to support the MIDI (Musical Instrument Digital Interface) protocol. This protocol allows different brands to Communicate and interact with music devices. This article will introduce how to use PHP to communicate with the MIDI protocol and give code examples.

First of all, we need to understand some basic knowledge of MIDI protocol. The MIDI protocol is a digital communication protocol that defines the data format and communication method between music devices. MIDI messages consist of three bytes, namely status byte, data byte 1 and data byte 2. The status byte is used to specify the type of MIDI message, and data byte 1 and data byte 2 are used to transmit specific data. For example, 0x90 represents the "Note On" message and 0x40 represents the volume.

To use PHP to communicate with MIDI devices, we can use PHP's serial communication extension library. The following is a simple code example that demonstrates how to send MIDI messages to a music device through PHP:

<?php
// 打开串口通信
$serial = new PhpSerial();

$serial->deviceSet("/dev/ttyUSB0");
$serial->confBaudRate(31250);
$serial->confParity("none");
$serial->confCharacterLength(8);
$serial->confStopBits(1);
$serial->confFlowControl("none");

$serial->deviceOpen();

// 发送MIDI消息
$statusByte = 0x90; // Note On 消息
$dataByte1 = 60; // 中央C
$dataByte2 = 127; // 最大音量

$message = pack("C*", $statusByte, $dataByte1, $dataByte2);
$serial->sendMessage($message);

// 关闭串口通信
$serial->deviceClose();
?>

In the above code, we first use the PhpSerial class to instantiate a serial communication object, and then Set serial port parameters, such as device name, baud rate, parity, etc. Then, call the deviceOpen method to open the serial port, and use the sendMessage method when sending MIDI messages. Finally, call the deviceClose method to close the serial port.

The above code is just a simple example. In actual use, we can modify it according to specific needs. For example, we could write a function to send different types of MIDI messages, or to receive MIDI messages from a music device. At the same time, we can also add error handling and exception handling mechanisms as needed to ensure the stability and reliability of communication.

In summary, by using PHP and MIDI protocol, we can communicate with music equipment. This article gives a simple code example that demonstrates how to send MIDI messages to a MIDI device using PHP. I hope readers can further explore and apply PHP and MIDI protocols and improve the application level of music technology by studying the content described in this article.

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