Language
Country/Area
No result found
The secret of audio compression: What amazing technology is hidden behind MP3 and AAC?
In the world of digital audio, audio encoding formats such as MP3 and AAC have become part of our daily lives. Not only do these formats allow us to easily store and transfer music, they also utilize intricate techniques that allow us to barely hear the sound quality lost during the compression process. What amazing technologies are hidden behind these formats?
Basic concepts of audio encoding formats
An audio encoding format is a content representation format used to store or transmit digital audio. These formats can effectively reduce file size and facilitate online streaming. For example, MP3 and AAC are the most common audio encoding formats, both of which use modified discrete cosine transform (MDCT) and perceptual coding algorithms.
The audio content is usually wrapped in a container format after encoding, so that the user does not have a raw AAC file, but a .m4a audio file, which is an MPEG-4 Part 14 container containing AAC encoded audio. .
Choose between lossy and lossless compression formats
Audio encoding formats can usually be divided into lossless formats and lossy formats. Lossless formats reduce audio data to the total amount of data required to represent the sound, but can be decoded back to the original, uncompressed form. In contrast, lossy formats further reduce the bit resolution of the audio, which can significantly reduce the amount of data, but results in irrecoverable loss of sound quality.
Most transmitted (streamed) audio usually uses lossy audio encoding because smaller file sizes are easier to distribute.
Historical background of technological evolution
The history of audio coding technology can be traced back to the 1950s, when Bell Labs submitted a patent for differential pulse code modulation (DPCM). Over time, many techniques for perceptual coding were developed, including linear predictive coding (LPC) and the coding-excited linear prediction (CELP) algorithm proposed in the 1980s.
In about 1974, the discrete cosine transform (DCT) was developed, which later provided the basis for the modified discrete cosine transform (MDCT) used in modern audio compression formats such as MP3 and AAC.
Technical principles of MP3 and AAC
The reason why MP3 and AAC can achieve effective audio compression is that they take advantage of the human ear's perceptual characteristics of sound and remove unnecessary data through a perceptual coding model. The main feature of MP3 is that it exists in the form of a data stream, while AAC is regarded as a more modern and effective encoding format, which can provide better sound quality, especially at high bit rates.
Like many other audio encoding formats, MP3 and AAC follow the principles of perceptual encoding, trying to remove certain data from the audio source in a way that is imperceptible to the human ear.
The future of audio encoding formats
As technology advances, audio encoding formats will continue to evolve. Emerging technologies such as circular audio and more efficient lossless compression are gaining traction. More efficient encoding standards may emerge in the future, improving sound quality while further reducing the storage space required.
Conclusion
Understanding audio encoding formats such as MP3 and AAC not only helps us appreciate music better, but also makes people curious about the technology hidden behind them. Therefore, the evolution of audio encoding and technological advancements continue to challenge our understanding of sound quality and storage convenience. Can we expect more amazing audio technologies to appear in the future?
