In May 2021, Apple stated that with the inclusion of Spatial Audio, Apple Music would have industry-leading sound quality for its customers. As an artist, Spatial Audio offers you the chance to provide your audience a genuinely multi-dimensional audio experience. You’ll also be able to listen to over 75 million songs, including lossless versions, with Apple Music members. In June 2021, users of Apple Music get these new services without paying an extra fee. This invites some paid subscription music service users who previously used Spotify to migrate to Apple Music. But will lossless audio really deliver a better music quality and music listening experience?
What is Lossless Audio?
“Lossy” compression and “lossless” compression are the two primary forms of compression. Lossy compression happened when the original sound is less fully developed. Still, the file size is smaller (one hopes mostly unnoticeable aspects of the sound, but that depends on how aggressively you compress it). MP3 and AAC are commonly used lossy compression formats, although there are lossless versions of each. Even while a lossless compression still results in a smaller file size, it does so without compromising sound quality. While both MP3 and AAC offer lossless variants, FLAC is perhaps the most well-recognized example of lossless audio compression.
In many cases, the data included in the original source file is lost when audio compression methods are used. With lossless compression, all of the original data is retained. It was created by Apple itself and utilized Apple Lossless Audio Compression (ALAC). ALAC, which is currently found only in the iTunes Store and Apple Music, now encodes all of the music offered in the library in resolutions ranging from 16-bit/44.1 kHz (CD Quality) up to 24-bit/192 kHz. This allows Apple Songs customers to stream music with lossless audio compression.
Parameters of The Lossless
In this article, we discuss the realm of audio in digital format. Of course, it will be much different if we discuss analog designs such as ancient times that used cassette tapes or even LPs. There are three parameters that we need to understand together. The first is resolution or bit-depth, the sampling rate, and the bit rate. The combination of bit-depth and sampling rate will determine the bit rate. Let’s discuss them one by one.
Bit depth is the number of bits of information in each digital audio sample utilizing pulse-code modulation (PCM), and it directly corresponds to sample resolution. Bit depth examples include Compact Disc Digital Audio, which operates 16 bits per sample, and DVD-Audio and Blu-ray Disc, which can handle up to 24 bits per sample. Remember that this is a digital realm. Bits represent binary digits, or the numbers 0 and 1. Simply put, if there is 16-bit audio, then the information from the song is stored in 16 binary numbers, which can be 0 and 1.
Sampling is the process of converting a continuous-time signal to a discrete-time signal in signal processing. The conversion of a sound wave (a continuous movement) to a sequence of samples is a frequent example (a discrete-time call). A sample is a value or group of values at a specific moment in time or place. A sampling is an activity or subsystem that collects samples from a continuous signal. A theoretical ideal sampler generates samples at the appropriate locations comparable to the instantaneous value of the constant signal. So that the sampling rate is defined as the number of sound samples taken in one second. No wonder the unit of sampling rate is Hz, which is the unit of frequency. Suppose you want to understand it more deeply. In that case, you can look at the Nyquist Theorem to find out why audio engineers choose a particular sampling rate, for example, 44,100 or 48,000 in their work.
Bitrate in digital multimedia refers to the quantity of information or detail recorded per unit of time of a recording. The bit rate is determined by various factors, including the sampling rate and the bit-depth. The following formula may be used to compute the bit rate of PCM audio data:
Bitrate = sampling rate x bit depth x number of channel
Let’s take an example of calculating CD-quality audio. Generally, the bit-depth used is 16-bit with the number of sampling 44100 times in one second. Meanwhile, generally, we hear audio in CD format on stereo channels or two channels, left and right channels (remember, you hear music with two ears, a pair of headsets, left and right). So the calculation becomes : 16 x 44100 x 2 = 1,411,200 bit in a second. This amount will be used to calculate the size of the file that meets the storage media, both on your computer and on your smartphone. For example, the song is 3 minutes long, then you just have to multiply the bitrate by the duration. (This simple calculation applies in constant bit rate format, it will be different if the variable bit rate is used, which is a condition where the bit rate does not have the same value and is adjusted to the needs of the song)
So What Is The Relationship Between These Three Elements With The Experience Of Hearing Lossless Audio?
As Apple said that the ALAC format supports up to 8 channels of audio at 16, 20, 24, and 32-bit depth with a maximum sample rate of 384kHz. This will undoubtedly be extraordinary. We will listen to an audio file equivalent to the final quality released by the recording studio. However, the process of audio strands still continues to the ear through the equipment we use, namely the player equipment. Is the play equipment that we have capable of playing these specifications?
Most modern audio signals are stored in digital and, to be heard through speakers, they must be converted into an analog signal. DACs are therefore found in CD players, digital music players, and PC sound cards. Specialist standalone DACs can also be found in high-end hi-fi systems. How about these DAC specs in playing high spec formats? As stated by Apple, listening to the lossless audio guide, to hear the sample rate above 48KHz takes an additional DAC. This shows that there is a limit to the ability of the Device Player to play audio files with very high specifications.
Another problem arises if you listen to lossless audio with wireless devices via Bluetooth, for example, AirPods and wireless speakers. Apple devices use SBC / AAC codecs to play audio via Bluetooth wireless 5. Meanwhile AAC CODEC requires bit-depth limitations and sampling rates at 16-bit / 48kHz.
It can be concluded that lossless audio presence brings extraordinary changes to music lovers, especially audiophiles. However, the hardware in the market is not enough to play this high-resolution audio. Let’s look at the next 2–3 years, whether a high-capable DAC has been pinned on the latest devices