Lossy Audio File Types: How It Is Different From Lossless
Lossy is a word used in digital audio to describe the type of compression used to store audio data. The algorithm used in the lossy audio format compresses the audio data in such a way that it discards certain information. This loss of signal means that the encoded sound is not identical to the original.
Lossy audio produces lower quality audio and has a smaller file size.
Lossy compression is also called irreversible compression because data that has been deleted is impossible to recover.
What is the difference between Lossy and Lossless?
When you create MP3 files by ripping one of your music CDs, some details of the original recording are lost, making it a lossy format. This type of compression isn’t just limited to audio; for example, JPEG image files are also lossy compressed.
Sheets of colored paper compressed into a ball
This method is the opposite of lossless audio compression used for formats like FLAC, ALAC, and others. In this case, the audio is compressed in such a way that the data is not deleted. The sound is identical to the original source.
Lossy archives take priority when it comes to compatibility. While lossless files are only supported by some devices and apps, a lossy audio format like MP3 will work on almost any device.
How Lossy Audio Compression Works
Lossy compression makes certain assumptions about frequencies that the human ear is unlikely to detect.
When a song is converted to a lossy audio format such as AAC, the algorithm analyzes all frequencies and then discards the frequencies that the ear should not be able to detect. These low frequencies are filtered or converted into mono signals that take up less disk space.
Another technique eliminates very quiet sounds that the listener is unlikely to notice, especially in the loudest part of the song. This approach reduces the size of the audio file while maintaining the highest possible audio quality.
What happens to the audio when it is compressed?
Lossy compression introduces artifacts. These artifacts are unwanted sounds that are not in the original recording but are a by-product of compression. This noise degrades sound quality and is noticeable when music files are converted using low bit rates.
Various types of artifacts affect the quality of the recording. Distortion is one of the most common artifacts. For example, distortion makes the drums feel weak, without any real beat. Song voices can also be affected, resulting in harsh vocals and lack of detail.
In many cases, casual listeners can’t tell the difference between lossy and lossless encoding, although some audiophiles using very expensive equipment claim to hear the difference. The difference in quality is only noticeable when very low data rates or aggressive compression algorithms come into play.
Why compress audio files?
Most digital audio formats use some form of compression to efficiently store sound. Without compression, the file sizes would be very large.
For example, a typical 3-minute song stored as an MP3 file is between 4MB and 5MB. Using the WAV format to store the same song, but without compression, results in a file size of approximately 30MB, at least six times that size. Fewer songs fit on your smartphone or hard drive when you choose uncompressed audio formats
