Maybe you’re a musician who has done the hard work of studying audio theory, writing or arranging your music, practicing it, recording it, and now you want to present it to the world. What is the best file format for your finished product? Or you could be a music lover looking for the best way to permanently store all your music. You might already have the music in some kind of digital form, or you might be ripping it from CDs or vinyl records. What audio formats will optimize your collection?
Choosing the right file format matters. For one thing, the format you use will affect the authenticity of the sound of the music. File formats also determine what kinds of devices will be able to play the music. In this guide, we will look at the different audio file formats that are available, what they offer you, and how to make the best use of them. But first, let’s get an understanding of what digital audio files are.
So, what is the best audio file format for you?
To choose what is the best audio file format to use, you need to look at your purposes for your files. Here are some common uses, with suggestions about the best audio formats for each one:
- Are you burning your music files onto a CD? For that, uncompressed (WAV or AIFF) file formats are the standard. You want to start with the highest quality file you can when you burn music.
- Are you archiving your music? A lossless compressed format like FLAC or ALAC will allow you to store your files as efficiently as possible without losing audio quality.
- Are you digitizing music from vinyl? Again, a lossless compressed format will give you the best sound quality while allowing you to store more files.
- Are you looking for the ultimate listening experience? Lossless compressed or uncompressed formats provide the best listening if you have a player that is compatible with the format. To get the most out of listening to lossless recordings, you want to listen with high-quality equipment that will deliver the full range of sound from your recording.
- Are you sharing your music with the public? You will need to use lossy file formats because of their small size and device compatibility. Just about any device will play an MP3 file.
Digital audio files
When music is recorded, the recording device takes the soundwaves from the air and translates them into a physical form. In analog recording, the recording device stores the music as one continuous audio signal on a physical medium like a vinyl record or a tape. In digital recording, the soundwaves are turned into a series of many little digital signals. These digital signals are like tiny bits of sound, similar to the way that a digital camera turns images into millions of little pixels.
This digital data can never be exactly like the waveform from the original sounds in the air, just like you can’t exactly duplicate a curved image through little square pixels. But the more tiny signals the computer creates, the closer it will be to the original waveforms. With enough digital signals, you eventually reach the point where the human ear can’t really tell the difference between the digital sound and live music. Again, it’s just like with digital pictures — the more pixels per inch, the more life-like the picture will look, to the point where the eye can’t tell that the digital picture is different from a real physical image. More density of signal data means more realistic sound.
There are many different types of audio file formats that use different densities of signal data. This signal density determines the sound quality that a file format will have. If you are recording music on a computer, the computer will probably store the audio in a format that preserves as much sound quality as possible. If you are converting analog recordings to digital, you may be given a choice between a higher-quality or lower-quality format.
Let’s take a look at the different categories of formats, starting with the ones of the highest quality.
Lossless audio formats
A lossless audio file format is a format that captures the maximum amount of signal data possible. Therefore, it will be as close to the sound of the “raw” music as you can get. We call these formats “lossless” because there is no loss of sound quality.
Lossless format files give the most authentic, “like you’re right there in the room”, sound quality that is possible from a digital recording. This makes them very attractive in terms of music quality. But because they contain such a huge number of digital signals, the files are very large. Some of the lossless formats can be compressed somewhat in order to decrease the file size; others do not allow any compression.
Uncompressed lossless formats
The most common uncompressed audio file formats are WAV and AIFF.
- WAV (which stands for “Wavefile Audio File Format”) is a format that was developed by IBM and Microsoft. WAV is the standard file format for uncompressed audio on the Windows operating system.
- AIFF (which stands for “Audio Interchange File Format”) was developed by Apple and it is the standard uncompressed format on iOS devices.
In the past, some Macs would not play WAV files, but now both Windows and iOS devices play both formats.
Here are the pros and cons of using uncompressed lossless audio formats.
- You get top-level sound quality.
- If you’re starting from a digital recording, you won’t need to do any conversion because the uncompressed format is the way the computer originally stored your music
- The large size of uncompressed music files limits their usability. You may not be able to store a large number of uncompressed files on your computer, and they are difficult to download or distribute. (If you have ever tried to email a WAV file, you know what we mean!).
Compressed lossless formats
Compressed lossless file formats take all the audio information from the recording and store it in a different style that takes less space, but all the digital signals are still there. As a result, the files are smaller, but they’re still lossless because there is no change to the waveform or the sound quality of the recording. Because compressed files are smaller, they are easier to store and transfer and are compatible with more >devices.
Common compressed lossless audio formats include FLAC and ALAC.
- FLAC format can be either compressed or uncompressed. The uncompressed form is just as big as a WAV or AIFF file. If you’re converting an uncompressed file to FLAC format, it will be saved in uncompressed FLAC format unless you choose the compression option. FLAC stands for “Free Lossless Audio Codec”. FLAC is an open-source format that many devices recognize.
- In ALAC format, compression is the only option. ALAC stands for “Apple Lossless Audio Codec”. Apple originally created ALAC, but they have released it to be open-source. ALAC files are put in a container called MPEG-4 format.
A compressed FLAC or ALAC file can be anywhere from 25% to 50% the size of an uncompressed version of the same recording.
What are the pros and cons of compressed lossless formats?
- You still get the best possible sound quality.
- Compressed files are easier to store and transfer.
- Both FLAC and ALAC formats are compatible with a variety of players.
- These compressed files are still too large for some uses. Many small devices like phones and tablets cannot download them.
- A lot of music players do not play these formats.
Because of these limitations, you may need still more compression, even though you will have to sacrifice some audio quality to get a smaller file.
Lossy file formats
Due to the lossless huge file size, even in its compressed version, many times a more aggressive type of conversion is needed. This sacrifices quality on order to achieve a small file size. The files generated from this kind of conversion are called Lossy.
It’s important to state that the parts lost during this process are inside the human audible spectrum range, meaning converting to lossy loses audible information. (as opposed to what many think, that it only affects frequency response in ultra-high and ultra-low frequencies). In other words, it’s possible to hear the difference between a lossy and a lossless file. Of course, there is a wide variety of lossy formats and there are highly trained years, but it’s undeniable that the losses are in a range which is perfectly audible by a normal human being.
The most common lossy audio format is our old friend the MP3 format. Another common lossy format is Apple’s AAC format. An MP3 file can be as small as 2% the size of a WAV file of the same recording.
Pros and cons of the lossy formats?
- These smaller, lossy files are much easier to download, store, and share.
- The sound is good enough for many purposes.
- Lossy files do not have the full quality of sound that lossless formats do.
Comparing file sizes of different audio formats
A member of our staff took a recording of one song and stored it in five different audio file formats. In this graphic, you can see the difference in size between the WAV and AIFF files, the compressed FLAC and ALAC (MPEG-4) files, and the MP3 file.
Clearly, there would be many instances where the lossy MP3 file can do the job that the bigger lossless files can’t.
These are the different types of audio file formats. Next, let’s talk about best practices for converting one format to another.
Transcoding is the process of converting a digital file from one format to another. This is how you create a compressed audio file from the original uncompressed file. Most likely, the recording software on your computer already has built-in functions that will convert your music into compressed formats. But if not, or if you want a particular audio format that your software doesn’t offer, there are websites that will do transcoding online.
You always want to be sure that you are converting the right way to get the right results. Here is how to optimize your transcoding efforts.
Good vs. bad transcoding
Here’s how to make sure that your transcoding is working for you and not working against you.
You understand now what the different audio file formats are, and that is the first step. You know which formats lose sound quality and why. The next thing you need to understand is that when you remove sound quality from a file, that lost quality is gone forever. In other words, if you transcode something into a lossy format, you do not want to take the lossy file and try to convert it back to a lossless format. You won’t get the lost signals back!
The types of conversions that can be helpful are:
- From lossless to lossless: Taking a lossless file format like a WAV/AIFF and converting it to another lossless format like a FLAC or ALAC file;
- From lossless to lossy: Taking a lossless file format and converting it to an MP3 or AAC. Going from a lossless format to a lossy format is called downsampling.
The type of conversion that will not do any good is:
- From lossy to lossless: Don’t take an MP3 and try to convert it back to a FLAC or WAV format. Going from a lossy format to a lossless one is called upsampling, and it will not accomplish anything. An upsampling conversion will take the data from the MP3 and space it out bigger, but you won’t get back the digital signals that were removed to make the MP3 in the first place. Therefore, you will end up with a big file, but it won’t sound any better than the MP3 did.
- From lossy of a certain quality to a lossy of the same quality: Re-doing a transcode only results in more losses. Do not convertwith the same codec/transcode twice!
- From a lower quality lossy to a higher quality lossy: That’s also upsampling. Quality lost is forever lost. Converting to a higher spec won’t make the final audio better. The source file must always be of a higher quality than the resulting file’s quality.
The same happens when converting to a higher sample rate or audio bit depth. You will never the audio information as if you have recorded right away with the higher parameter.
If you are downsampling from a lossless format to a lossy format, DO NOT delete your old lossless file! Keep it around so that you always have a high-quality version of your music.
Is there any other audio file format?
I have a simple answer to you, and that’s a “yes”. You probably heard a lot of the ones listed before, but there are still plenty of file formats out there. To wrap this topic up we’re going to briefly talk about some of the most known and somewhat common.
Musical Instrument Digital Interface (.midi)
Even though this one isn’t exactly an audio file as the ones we’ve listed before, it also has its use when it comes to making music. If you are a music producer, or a composer, you’ve probably already heard of this sort of audio file. Computer keyboards and other computer-based musical tools are the ones that use Musical Instrument Digital Interface (.midi) more commonly. But what does that mean for you? Simple, if you create a music in your DAW, if you’re playing using keyboard or something, and you can easily store that melody. You can save musical notes, rhythm notation and other information, into a file you could open later on. You can also share those files with anyone else that has a software that reads midi files.
Sun Audio (.au)
If you ever worked with any of UNIX’ operating systems maybe you’ve heard about Sun Audio. It was originally headerless, simply 8-bit μ-law-encoded data at an 8000 Hz sample rate. Just to give you an idea, hardware from other different brands often used sample rates as high as 8192 Hz.
Emblaze Audio (.ea)
It offers compression similar to MP3 formats, but the whole purpose here was that it could be played with a JAVA applet-a miniature Internet program. Online greeting cards often use JAVA applet programs for motion and .ea sound files to play music.
Windows Media Audio (.wma)
Windows Media Player developed .wma to compete with the MP3. Microsoft claims that the WMA files are compressed three times more than MP3s yet retain their original sound quality.
Ogg Vorbis (.ogg)
It’s another compressed source code similar to MP3, but like WMA, more compressed. Ogg Vorbis is also open source (which means free to use, unlicensed). While MP3 compresses data at a constant bit rate, Ogg uses a variable bit rate. To give you a better idea, let’s say you are copying pieces of silence into MP3 format, the compression bit rate stays the same as if you were compressing the sound of an entire orchestra. But if you are copying pieces of silence into Ogg, your compression rate will drop to nothing. The rate varies with the need.
STEMS by Native Instruments
This is relatively a new audio file format I’ve started working with, not long ago. It’s an open multi-track audio format, which enhances creative possibilities for DJs, producers, and live performers. A Stem file contains a track split into four musical elements: A drums stem, a bassline stem, a melody stem, and a vocal stem for example. I wouldn’t say that this format is exclusive to electronic dance music, but it definitely has more presence there. Not only it allows DJs and performers to mix things up live during their shows, it also means a whole new revenue for producers. If you’re into electronic dance music production, look it up.
Why is audio file format understanding important?
We live in the digital era, and just like in any business model, you have to provide your clients the best product. In the music industry that means you have to provide the adequate audio file format for your audience, with the best possible quality. For instance, would be appropriate to share a WAV lossless file format with someone that is probably just going to play your music on their cell phone? No. I don’t think people would have enough storage space anyways, so they’ll probably just remove your music, or maybe they won’t even download it. Mp3-128kbps files are more popular when it comes to downloading, storing and copying. But if you are planning to distribute your music, then yes, go with lossless files. Getting your music into the hands (and ears) of everyone is key these days and providing the appropriate files is just part of the drill.
We recommend that you always keep one copy of your music in its uncompressed format. That way you will always have the option to transcode it into whatever compressed format will be best for a particular situation.
Both uncompressed and compressed formats support metadata tagging and cover art.
So you can see that each type of audio file format has its own purpose and usefulness. And now you understand which audio formats will be the best for different times and reasons. Happy music-making!