4.2 Properties and formats of media files

Audio files

Digital audio is used in many media products, including podcasts, videos, games, and apps. To use audio effectively, media producers need to understand how sound is recorded, how quality is controlled, and which file formats are best for different uses.

What is sample rate?

Sample rate is the number of times per second that a sound is captured when it’s recorded. It is measured in hertz (Hz). The most common sample rate for music is 44,100 Hz (or 44.1 kHz).

A higher sample rate means more detail is recorded, which results in better sound quality. However, it also increases file size.

What is bit depth?

Bit depth is the amount of data used to store each sample. It affects how accurately the sound is recorded, especially the volume and clarity.

Higher bit depth means better sound quality and a wider range of volume levels, but it also means larger files. CD-quality audio usually has a bit depth of 16 bits.

Audio compression

Audio compression is used to reduce the size of audio files, making them quicker to stream or download. There are two main types of compression:

Lossy compression – removes parts of the sound that are less noticeable to human ears to shrink the file. This reduces quality slightly. Example: .mp3
Lossless compression – shrinks the file without losing any sound data. Example: .flac

Uncompressed audio files

Uncompressed audio files keep all the original sound data, giving the highest possible quality. These are often used in professional editing or recording.

Example: .wav, .aiff
Best for: studio recording, sound editing, archiving
Limitations: large file sizes, slower to upload or share

Compressed audio files

Compressed files are smaller, making them easier to stream, share, or store. The trade-off is that sound quality may be reduced, depending on the type and amount of compression.

Lossy examples: .mp3, .aac
Lossless examples: .flac, .alac
Best for: online streaming, mobile apps, podcasts
Limitations: may not sound as good as uncompressed formats on high-quality audio systems

Choosing the right format

The audio format you choose depends on how the sound will be used:

.mp3 – good for podcasts, websites and mobile devices where small size is important
.wav – ideal for professional editing and storing original high-quality audio
.aac – used by many streaming services, like Apple Music
.flac – best for users who want high-quality audio in a smaller size

Choosing the right audio file format helps ensure your media product sounds great, performs well, and meets the needs of the audience and platform.