Audio Formats and File Types

Understanding Audio File Types

You will come across many audio file types in the audio world. That said, we will mention several here that are very common to most DAWs. They can be categorized into 3 main groups.

• Uncompressed audio formats: WAVE, AIFF & PCM

• Lossless audio formats: FLAC, WMA, ALAC

• Lossy audio formats: MP3 & AAC

Understanding the difference between uncompressed and compressed audio file types is essential. Lossy or compressed file types like MP3s throw away audio information to reduce the file size. When we compress the file, it becomes significantly smaller than the original one. This has its advantages when distributing the content. However, always shoot for the best quality when recording audio or downloading samples. The reason for this may be self-evident to you - but I must explain. When you start with a lossy compressed audio source (like MP3 or AAC), further compression will compound the effect of the thrown-away audio information. This can damage the file. It also makes any processing you do useless. So, trying to preserve as much as possible from the beginning is best. Notice how compound compression has damaged the second example below. It is an industry-standard to deliver your final audio file (2-mix) to mixing and mastering engineers in an uncompressed format. They simply cannot and will not work with compressed files. Take a look at these two waveforms. They are the same performance rendered to two different qualities - WAV and MP3. The blue waveform on top is the MP3.  

A few more terms you will come across when you deal with audio file formats are Sample Rate, Bit Rate, and Bit Depth. We will cover these below.  

Sample Rate

The sample rate is the number of times the audio is sampled per second. For example, CD audio has a sample rate of 44100 Hz. This means that the audio is sampled 44100 times every second. The sample rate is measured in "Hertz" - a unit of frequency describing cycles per second. Standard CD-quality audio uses a sample rate of  44.1 kHz (k means times 1000). Sampling Rates range from 8000 Hz (very, very low quality) to 192 000 Hz (very high quality). The disadvantage of very high sample rates is that they deliver huge files, and people cannot hear improvement after 44100 Hz.  

Bit Depth and Bit Rate

Bit Rate and Bit Depth are two more important aspects of digitized sound. From the export (or render) window in your DAW, you can probably choose from 16, 24, and 32-bit. SoundBrige allows these three options as well as a 32-bit float option. This refers to Bit Depth - the number of possible values to represent a signal sample. Professional studios usually offer bit depths of 24 and 32. In digital multimedia, Bit Rate refers to the number of bits within a unit of playback time to represent a continuous medium (such as audio) and describes the character of the sample.  

More about Lossy Formats Like MP3

You can customize the degree to which the MP3 retains or loses information during the encoding and compression process by tweaking the bit settings. A lower bit rate means the encoder will discard more audio data during the compression process, affecting audio quality on playback. Bit Rates for MP3 files range from 16 kilobytes per second (kbps) to 320 kbps. A Sample Rate of 44100 Hz and a Bit Depth of 16/Bit Rate of about 320 kbps is known as the Red Book standard for audio CDs. Here is a comparison of lossless and lossy files with their associated quality vs size.

For professional sound quality, record and render audio at a rate of at least 44.100 kHz and a depth of 24 bits. This way, further processing, such as mixing and editing, will not result in degradation. If you must encode/record to MP3, aim for 320 kbps - 32-bit float.