AF’s Weblog

April 13, 2009

Audio Encoding: What Lies Ahead?

Introduction to Audio Encoding

In today’s high definition world, we want the best quality in every film, picture, and sound we encounter. Blu-Ray DVD’s seem poised to take over the market, pushing the inferior DVD’s down the same path as the VHS tape. In much the same way, we see digital audio pushing for the same quality. Although the popularity of the iPod and mp3s has given rise to an age of over-compressed, low-quality music, we also see a rise in vinyl sales, as well as developments such as Sony’s Super Audio CD (SACD). This implements a relatively new process to encode audio, paving the way for a massive change in the quality of music we listen to, if it is accepted.

Analog vs. Digital

In order to understand audio encoding, the difference between analog and digital must be understood. Something that is analog is an uninterrupted, pure, natural sound. The human voice, a guitar, and a vinyl record are all examples of analog sound. When a vinyl record is cut, a needle senses the vibrations from an audio source and cuts it exactly into the vinyl. This is why vinyl could be said to have the highest sound quality, and is still popular today, despite many alternatives and developments. An analog signal can encompass all frequencies, even the inaudible. This is why a live orchestra sounds more “full” than a recording, even of the highest quality. Audiophiles will argue that the energy of the inaudible frequencies adds to the quality of sound, even though they cannot be perceived by the ear.

Ouverture

A digital signal is a replication of an audio signal by a number of ones and zeros. It is the same way a picture on a computer screen is replicated by thousands of intensity values represented in binary code. The music on an iPod, a compact disc, and an mp3 are examples of digital replication. Even many modern musical instruments have implemented digital sound, from digital keyboards to electronic drums to guitar pedals. Digital sounds can be made with a programmable chip, rather than a circuit, and is much more reliable, inexpensive, and easy to mass produce as a result. However, there are drawbacks to digital sound that sacrifice the sound quality, and these drawbacks are being constantly developed and upgraded to replicate an analog signal more precisely.

Now let’s take a closer look…

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Conclusion

Thus, 1-Bit modulation has been implemented in many new “high definition” audio devices, and developers continue to use this process to expand into multi-bit modulators and other hybrid converters. It has become accepted among audiophiles, and is slowly taking the place of PCM. Is one better than the other? It is still debatable. However, 1-Bit modulation allows for simpler circuitry and much better noise shaping in lower frequency bands. The SNR is much better than PCM, except in the higher frequency range, where much of the noise is inaudible anyway. The design is simpler, using more digital implementation than PCM, and as programming advances, digital functions like noise shaping will be enhanced.

Once 1-Bit modulation starts to become affordable, consumers will begin to realize the poor quality of mp3’s. Steps will be made to expand 1-Bit audio into the portable market, and “high definition” audio will become the norm. Until then, only the select few who have heard the differences will know how much better sound quality can be, and will only strive to educate the rest.

To read the full detailed article see Audio Encoding

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