Audio Formats at a Glance, What are MP3, AAC, and AC3?

The world of audio formats is now bigger than ever. Audio coding has become an integral part of people’s lives. Almost all applications in which you play sound, be it a simple phone call, streaming music via Spotify, voice messages on WhatsApp, or streaming music from the cell phone to the car. All this is only possible thanks to different audio formats.

But what exactly are these formats, and why are there different ways of storing music?

What exactly is an audio format or an audio codec?

After recording sound, the data from the microphone is usually saved as so-called raw data. That is, the device saves all sound frequencies recorded, possibly including those that the human ear cannot perceive at all or that have no meaning for perception.

However, after saving the raw data, it remains relatively large and cannot easily be sent over the Internet or the telephone line. The task of an audio codec is to compress this raw data into a specific format, e.g., the MP3 audio codec compresses the raw data into the .mp3 format.

The data is significantly smaller, you can send it over the Internet, and then compress and play it back at the other end. You also need an MP3 codec at the other end of the line, which can unpack the compressed format and play the music.

An audio codec is a program that can compress and decompress music/sound, ideally in such a way that as little data as possible is lost, and the sound still sounds exactly like the original after compression and decompression.

Many of the codecs used today work in a lossy manner. That is, the unpacked music data does not correspond 100% to the original data. However, a normal listener cannot distinguish the encoded music from the original.

Every codec works with a very important variable: the bit rate. The bit rate determines how many bits per second the codec has available to compress the music.

The higher the bit rate, the better the sound usually sounds after encoding and decoding. Typical data rates are 256 kbit/s for the MP3 codec, for example.

What is the difference between the audio formats?

Audio formats have developed a great deal over the last few years. In principle, every manufacturer can think of their own format to transmit music. However, some very well-known formats have emerged that are predominantly widespread in today’s world.

MP3 format

The first is the MP3 format, developed by the Fraunhofer Institute in Erlangen, Germany, among others. This is a lossy format that delivers a very pleasant sound at bit rates of around 256 kbit/s without introducing artifacts. That is, disturbances into the piece of music.

The patents for the MP3 format expired in 2019, so today, it is license-free, i.e., free technology.

AAC format

The AAC format, the so-called Advanced Audio Coding, is the successor to the MP3 format. Thanks to a new algorithm, this format offers the user better sound and the use of even lower data rates, which saves the battery of the end device. Likewise, AAC offers the so-called DRM function to prevent illegal copying of music.

The AAC codec has also been greatly improved in recent years, e.g., to the so-called Extended High-Efficiency AAC (HE-AAC), which can offer even better sound quality at low data rates. HE-AAC can also adjust the data rate depending on the piece of music. This not saves energy on the smartphone/tablet and also protects the data volume.

AC3 codec

With DVDs/Blurays, Dolby is usually the pioneer of audio codecs. Most people know it in these areas with its AC3 codec. You can use it, for example, with HDTV or Blu-ray, and can transmit up to 14 channels simultaneously to provide the user with a home cinema experience in their own home.

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