What is High-Resolution (Hi-Res) Audio?
I believe that people who are audiophiles are not unfamiliar with the Hi-Res certification. Under the constant improvement of the industry, Hi-Res Audio professional certification has become an essential requirement for products. What is the Hi-Res Audio certification?
Hi-Res defines the threshold of high-resolution music above the CD quality. That is, music with a sampling rate higher than 44.1KHz and a bit depth greater than 16bit. According to the official introduction, the most commonly used digital formats for high-resolution music are 192kHz/24bit or 96kHz/24bit. That is the first high-quality music standard proposed by Sony.
First of all, we must know that DTS, Dolby, SRS, WOW, BBE are not Sony’s standards. It is also inappropriate to directly express various audio formats and coding rate marks (24bit/32bit) on the product. Therefore, Sony very much needs a new logo that belongs to itself and is very recognizable to identify its products, which means that this product is certified as “sounds very good.” Thus, Hi-Res Audio was born!
▌What is Hi-Res Audio?
Hi-Res is the abbreviation of the High-Resolution Audio, which is the latest high-quality music standard proposed by Sony in 2014. Its sound quality performance far exceeds the existing compressed audio format, CD, and audio format specifications can be as high as 192kHz / 24bit or higher resolution. That is, the sampling rate is higher than 44.1KHz, and the bit depth is greater than 16bit. (16bit/44.1kHz coding rate has dominated the world for more than half a century)
▌What is the Sampling Frequency?
Sampling frequency (or sampling rate) refers to the number of times the signal is sampled per second during the analog-to-digital conversion process. The higher the number of bits, the more accurate the signal can be at the first measurement, so from 16 to 24 bits can have a significant leap in quality. High-resolution audio files usually use a 24-bit sampling frequency of 96kHz or 192kHz.
Hi-Res audio also has a disadvantage: the file is too large. The size of a Hi-res file can usually reach tens of megabytes, and some audio tracks can quickly consume the storage space on the device. Thankfully, current storage devices are cheaper than before, so it is easier to get larger capacity devices. But the file size still makes it challenging to transfer high-resolution audio on Wi-Fi or mobile networks.
▌How to Define Hi-Res Audio?
Although Sony first proposed hi-Res. To ensure consistency, the Consumer Technology Association (CTA), Digital Entertainment Group (DEG), and major record companies have joined forces to unify the Hi-Res audio definition standard. According to the definition of CTA: “Hi-Res high-resolution audio is lossless audio. It strives to restore the source sound to the maximum extent on the recording, and its sound quality performance is higher than that of the CD audio source.”
▌What can Hi-Res Audio Bring Us?
Hi-Res digitally captures the original analog audio source with almost no loss, thereby detailing but restoring various sounds. In traditional audio such as CD, part of the sound information is recorded. Only the necessary part is retained.
Downloading from Amazon, iTunes, Tidal, etc., the available compressed file bit rate is relatively low. Using lossy compression means losing data during the encoding process, which in turn means sacrificing resolution for convenience and smaller file size.
High-resolution audio contains a lot of information about the sound, such as “thickness, fineness, depth, the sound pressure level of sound,” etc. The amount of sound information is about 6.5 times that of CD.
For example, to illustrate why it sounds better than MP3, let’s compare the relative bit rates. The highest quality MP3 has a bit rate of 320kbps, while the data rate of a 24bit/192kHz file is 9216kbps. CD is 1411kbps.
Therefore, the sound quality of high-resolution audio is closer to the original sound. You can feel the details and atmosphere of the previous CD that cannot be heard in the CD, such as the singer’s breath and live music. It seems to be in a recording studio or live concert. Immerse yourself in your favorite music and discover subtle details that you have never heard before.
▌Hi-Res Audio File Format
- Direct Stream Digital Interchange File Format (DSDDIFF), the file extension is .dff. It is 1-bit quantized, and the supported sampling rates are 2.8224MHz, 5.6448MHz, and 11.2896MHz, of which 2.8224MHz audio files can support multiple channels.
- Direct Stream Digital Stream File (DSF), the file extension is .dsf. It is 1-bit quantized, and the supported sampling rate is 2.8224MHz, which can support multi-channel audio files.
- Direct Stream Transfer (DST), the file extension is .dst. That is a DSD compressed file obtained after lossless compression of the DSDIFF file. It is 1-bit quantized, and the supported sampling rate is 2.8224MHz, which can support multi-channel audio.
- Digital eXtreme Definition (DXD), the file extension is .wav or .bwf. The sampling rate it supports is 352.8kHz, which can only support 2-channel audio files.
- Linear Pulse Code Modulation (LPCM), the file extension is .wav. The sampling rate it supports is 192kHz or 96kHz, the quantization bit is 24bit, and it can support two-channel and 5.1-surround sound audio files.
- Free Lossless Audio Codec (FLAC), the file extension is .flac. The sampling rate it supports is 192kHz or 96kHz, the quantization bit is 24bit, and it can support two-channel and 5.1 surround-sound audio files.
▌What do We Need to Play Hi-Res Audio?
A set of excellent audio playback equipment can let us enjoy the superb effect of Hi-Res audio. Although expensive to purchase a costly high-fidelity audio system, Hi-res players and Hi-Res-enabled headphones, DACs, power amplifiers, speakers, and other equipment can be worth having.
For playback devices: To comply with the definition of the Hi-Res Audio logo, it means that it supports at least 24bit/192kHz PCM playback or recording capabilities. Besides, many of them also support DSD while considering compatibility. In addition to uncompressed PCM in WAV format, it can also read FLAC, ALAC, and other lossless formats.
Many audio industry devices have achieved this standard before, and Hi-Res Audio has standardized these logo standards. Having Hi-Res Audio stands for “This product has the function of playing high-definition music, or this product can express high-definition music.”
▌ Where can I Get Hi-Res Audio Resources?
With the continuous improvement of lossless compression technology, many online music companies now begin to launch high-definition music. People need to pay the membership to download these Hi-Res music files, such as the recently launched “Sony Selection” platform Hi-Res streaming music service. Besides, many record companies issue hi-res high-resolution music records, such as SACD, Blu-ray, and DVDs.