FLAC facts for kids

Quick facts for kids
Free Lossless Audio Codec

Developer(s)	Xiph.Org Foundation, Josh Coalson, Erik de Castro Lopo
Initial release	20 July 2001; 24 years ago (2001-07-20)
Stable release	1.5.0 / 11 February 2025; 5 months ago (11 February 2025)
Written in	C, C++
Operating system	Cross-platform
Type	Codec
License	Command-line tools: GNU GPL Libraries: BSD

FLAC stands for Free Lossless Audio Codec. It's a special way to store digital audio (like music) in a smaller size. Think of it like zipping up a file, but for sound! The cool thing about FLAC is that when you "unzip" it, the sound is exactly the same as the original. Nothing is lost.

FLAC was created by the Xiph.Org Foundation. It's an open format, which means anyone can use it without paying fees. It also works with metadata (information about the music, like the song title or artist) and can even show album cover art.

How FLAC Was Created

FLAC development began in 2000. Josh Coalson started the project. The main way FLAC files are structured was set in stone in March 2001. The first full version, 1.0, came out in July 2001.

In January 2003, FLAC joined the Xiph.Org Foundation. This foundation is home to other free audio and video formats. These include Vorbis and Opus.

Version 1.3.0 was released in May 2013. After that, the project's development moved to Xiph.org's main code storage. In December 2024, FLAC became an official internet standard. This means it's recognized as a reliable way to store audio.

How FLAC Works

FLAC takes regular digital sound data and makes it smaller. It does this without losing any quality.

Inside a FLAC File

A FLAC file starts with a special code: `fLaC`. Then comes some metadata. This is information about the audio, like its speed or how many sound channels it has. It can also include things like the album cover. FLAC uses something called Vorbis comments for text details like the song title or artist.

After the metadata, the actual sound data is stored. This sound data is broken into small pieces called "frames." Each frame has a header, the sound information, and a check to make sure it's correct. Each frame can be decoded on its own.

Making and Playing FLAC Files

When you make a FLAC file (this is called "encoding"), the sound is split into blocks. If there are multiple sound channels (like stereo), each channel is handled separately. The FLAC program then tries to find a simple mathematical way to describe the sound. It saves this description, which is very small. Then, it saves the "difference" between the original sound and this description. This difference is usually much smaller than the original sound data.

When you play a FLAC file (this is called "decoding"), the process is reversed. The program first gets the "difference" data. Then, it uses the mathematical description to rebuild the sound. Because FLAC is lossless, the sound you hear is exactly the same as the original.

For stereo sound, FLAC can sometimes combine the two channels. This can make the file even smaller.

How Much Can FLAC Compress?

FLAC can usually make audio files 50% to 70% smaller than their original size. The amount of compression depends on different settings. But no matter how much it compresses, you can always get the perfect original sound back.

The FLAC program has 9 different compression levels, from 0 to 8. Higher numbers mean smaller files, but it takes longer to create them. Playing FLAC files is always fast, no matter the compression level.

The main FLAC program is called libFLAC. It helps you create, play, and manage FLAC files. FLAC is free to use and doesn't have any patents. This means anyone can create their own programs that use FLAC.

FLAC Compared to Other Formats

FLAC is designed specifically for audio. Other general compression tools, like those used for ZIP files, can make audio smaller. But FLAC is much better at it. ZIP might reduce an audio file by 10-20%, while FLAC can reduce it by 40-50%. This is because FLAC understands how sound works.

FLAC is also great because it can be played quickly. This is true even for highly compressed files.

Since FLAC doesn't lose any quality, it's perfect for keeping your music collection safe. If your original CDs get damaged, a FLAC copy means you can always get a perfect copy back. If you use a "lossy" format like MP3, some sound information is thrown away to make the file smaller. You can't get that lost information back.

You can also use FLAC to convert music to other formats, like MP3. When you convert from FLAC, you don't lose any quality. This is different from converting between two lossy formats, which can make the sound worse.

Where FLAC Is Used

FLAC is supported by many devices and software.

Devices and Software

While MP3 is very common, FLAC support is growing. Windows 10, Android, macOS, and iOS all support FLAC by default.

Many other programs can play FLAC files, no matter what operating system you use.

Use in Archives

Because FLAC keeps perfect copies of audio, it's great for saving important sound recordings. The National Archives and Records Administration in the United States lists FLAC as a preferred format for digital audio. This shows how reliable FLAC is for long-term storage.

See also

In Spanish: FLAC para niños

• Comparison of audio coding formats
• List of audio player software that supports FLAC