MPEG-1 Audio Layer I (MP1) is an early digital audio compression format created in the late 1980s as part of the MPEG-1 standard. Developed by the Moving Picture Experts Group (MPEG), MP1 was designed to reduce the size of audio files while keeping decent sound quality.
When talking MP1, MP2, and MP3 you’ll often hear the term codec. A codec (short for coder-decoder) is a software or hardware tool used to compress and decompress digital audio or video files. Codecs reduce file sizes by removing redundant or less perceptible data, making storage and streaming more efficient. There are lossy codecs (e.g., MP3, AAC, Opus) that sacrifice some quality for smaller files and lossless codecs (e.g., FLAC1, ALAC) that preserve all original data. Codecs are essential for digital media, enabling everything from music streaming and video calls to Blu-ray movies and online broadcasting. Different codecs are optimized for specific tasks, balancing quality, file size, and processing power.
It uses a technique called lossy compression, which means it removes parts of the sound data that are less noticeable to human ears, making the file much smaller than an uncompressed version like a WAV file2. Originally, MP1 was intended for digital audio broadcasting and some early portable digital audio players.
| Audio compression format | Reasonable sound quality | Incredible sound quality |
|---|---|---|
| MP1 | 384 kbps | 448 kbps |
| MP2 | 256 kbps | 320 kbps |
| MP3 | 128 kbps | 192–256 kbps |
It offered reasonable sound quality but required a relatively high bitrate (around 384 kbps) to achieve good results. Over time, better compression methods were developed, and MP1 was quickly overshadowed by its successor, MPEG-1 Audio Layer II (MP2). MP2 provided improved compression efficiency and better sound quality at lower bitrates.
| Audio compression format | Reasonable sound quality | Incredible sound quality |
|---|---|---|
| MP1 | 8.6 MB | 10 MB |
| MP2 | 5.7 MB | 7.2 MB |
| MP3 | 2.9 MB | 4.3–5.7 MB |
Because of this, it became the standard for radio and television broadcasting in many parts of the world. However, MP2 itself was eventually outclassed by the much more famous MPEG-1 Audio Layer III, commonly known as MP3. MP3 became the most popular digital audio format in the late 1990s and early 2000s,
revolutionizing how people listened to and shared music. It offered even better compression, allowing high-quality sound at much lower file sizes, making it ideal for online music distribution and portable media players. While MP1 is now mostly obsolete, it played an important role in the early development of digital audio compression.
Footnotes
- FLAC (Free Lossless Audio Codec) is an open-source audio format that compresses audio without any loss in quality, unlike lossy formats such as MP3 or AAC. Developed by the Xiph.Org Foundation and released in 2001, FLAC reduces file sizes by 30–60% while keeping the original sound data intact, making it popular for audiophiles, archival storage, and high-resolution music playback. It supports high sample rates, multi-channel audio, and metadata tagging, and is widely compatible with media players and devices. Since it is royalty-free, FLAC remains a top choice for those who prioritize audio fidelity over file size. ↩︎
- A WAV (Waveform Audio File Format) is an uncompressed audio file format developed by Microsoft and IBM in 1991. It stores raw audio data in the Pulse Code Modulation (PCM) format, making it a high-quality option for professional audio recording, editing, and archiving. Because WAV files are uncompressed, they offer lossless audio quality but require significantly more storage space compared to compressed formats like MP3. For example, a 3-minute stereo WAV file at CD quality (44.1 kHz, 16-bit) takes up about 30 MB. While WAV is widely used in studios and broadcasting, its large file size makes it impractical for everyday music storage and streaming. ↩︎
- AAC (Advanced Audio Codec) is a high-efficiency audio format designed to provide better sound quality than MP3 at the same or lower bitrates. Developed in the late 1990s by a group including Fraunhofer, Dolby, Sony, and Nokia, AAC became the standard for Apple’s iTunes, YouTube, and digital radio. It supports higher sampling rates, more efficient compression, and multiple channels, making it great for both music streaming and surround sound. A 128 kbps AAC file generally sounds as good as or better than a 192 kbps MP3, making it a go-to format for modern digital audio. ↩︎
- Opus is a highly efficient, low-latency audio codec designed for both music and voice communication. Developed by Xiph.Org, with contributions from Skype, Mozilla, and Google, it became an open standard in 2012 under RFC 6716. Opus dynamically adjusts bitrate, sample rate, and latency, making it ideal for VoIP, streaming, and real-time applications like Discord, Zoom, and YouTube. It outperforms MP3 and AAC at low bitrates, providing near-transparent quality at 96 kbps while supporting bitrates from 6 kbps to 510 kbps. Due to its versatility and efficiency, Opus is considered one of the best modern audio codecs. ↩︎
Further Reading
Sources
- Wikipedia “MPEG-1 Audio Layer I” https://en.wikipedia.org/wiki/MPEG-1_Audio_Layer_I
- Data Tracker “The audio/mpeg Media Type” https://datatracker.ietf.org/doc/html/rfc3003
- Imagify Blog “Lossy vs Lossless Image Compression: What’s the Difference?” https://imagify.io/blog/lossless-vs-lossy-image-compression/
- Wayback Machine “MPEG Audio Compression Basics” https://web.archive.org/web/20150208104604/http://www.mpgedit.org/mpgedit/mpeg_format/mpeghdr.htm
- Izotope “What’s the difference between audio file formats?” https://www.izotope.com/en/learn/whats-the-difference-between-file-formats.html
