What is I2S Inter-IC Sound? Explanation of audio data transmission method

Explanation of IT Terms

What is I2S Inter-IC Sound? An Explanation of the Audio Data Transmission Method

I2S, short for Inter-IC Sound, is a common serial communication protocol used for transmitting audio data between digital audio devices. It is often employed in applications where high-quality audio is critical, such as audio codecs, digital-to-analog converters (DACs), and sound cards. In this article, we will delve into the details of I2S and explore how it works as an audio data transmission method.

Understanding I2S

I2S is a synchronous, serial communication interface designed to transmit audio data and control information between integrated circuits (ICs). It was introduced by Philips Semiconductor (now NXP Semiconductors) and is widely adopted in the consumer electronics industry. The protocol uses separate data and clock signals to enable the precise transfer of audio data.

Unlike other communication protocols, I2S is specifically tailored for audio applications. It supports bidirectional audio streaming, allowing for simultaneous audio data transmission and reception.

Key Components and Signals

To understand I2S, it is important to grasp the key components and signals involved in the communication process. The following signals are used:

1. Bit Clock (BCLK): This signal provides timing information for the data transmission. It defines the rate at which the data is sent.

2. Word Select (WS): Also known as Left-Right Clock (LRCLK), this signal differentiates between the left and right audio channels in stereo applications. It synchronizes the data sent over the serial data line.

3. Serial Data (SD): This line carries the audio data bit by bit. The data is sent in a serial format, hence the name “Inter-IC Sound.”

Transmission Process

The transmission process in I2S is straightforward. Here’s a step-by-step overview:

1. The data is presented according to a predefined format. Typically, the audio samples are expressed in linear PCM (Pulse-Code Modulation) format.

2. The bit clock (BCLK) starts to oscillate, indicating the sampling rate at which the audio data is transferred.

3. For each audio sample, a word select (WS) signal is generated. Its frequency is determined by the sampling rate and acts as a frame synchronization signal.

4. The serial data (SD) line transfers the audio data, encapsulated in frames, synchronized by the word select (WS) signal. The MSB (Most Significant Bit) is transmitted first.

5. The data continues to be transmitted until the desired audio duration is reached or until the transmission is terminated.

Benefits of I2S

I2S offers several advantages over other audio communication protocols. These include:

1. Simplicity: I2S is a straightforward protocol, making it relatively easy to implement and integrate into audio systems.

2. High-quality audio: As a purpose-built protocol for audio transmission, I2S ensures accurate and low-latency audio data transfer.

3. Compatibility: Due to its widespread adoption, I2S is supported by a wide range of audio ICs, making it highly compatible with various devices in the audio playback chain.

4. Flexibility: I2S supports different data formats and allows for customization, enabling manufacturers to optimize their audio systems based on specific requirements.


I2S, or Inter-IC Sound, is a serial communication protocol widely used in audio applications for transmitting high-quality audio data. Its dedicated design for audio transmission, simplicity, and compatibility make it a popular choice among audio device manufacturers. Understanding the key components and transmission process of I2S can help engineers and enthusiasts harness its potential in delivering exceptional audio experiences. Whether it’s a digital audio codec or a sound card, I2S plays a crucial role in ensuring pristine audio delivery.

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