Digital audio formats with better sound quality than CDs, which is based on the sampling rate used when an analog music file or a live performance is converted to digital data. It also means "lossless" compression, whereby none of the music has been removed such as with MP3 and AAC. In 2014, the record labels formalized the major categories (see high-resolution audio categories).
Early Attempts: SACD and DVD-Audio
In 1999, SACD and DVD-Audio were two high-resolution optical disc formats, but neither took off (see SACD and DVD-Audio). However, the sampling method in SACD did survive (see DSD).
High Resolution Via Download
Today, high-quality music is no longer bound to physical media. HDtracks (www.hdtracks.com) pioneered high-resolution audio via download and offers music titles at CD quality and greater. In addition, music played from the computer's memory (RAM) is not subject to jitter caused by an optical platter that is not rotating 100% evenly.
It's All in the Sampling
The above album from HDtracks is available for download in four lossless formats and three sample rates. When analog sound waves are converted to digital for CDs, 16-bit samples are taken 44,056 times per second (44.1 kHz), resulting in stereo data transferring to the digital-to-analog converter (DAC) for playback at a bit rate of 1409 kbps (1,409,792 bits per second). At 192/24, the analog waves are converted into 24-bit digital samples 192,000 times per second (192 kHz), resulting in a bit rate of 9216 kbps. For a sampling comparison, see high-resolution sampling rates
. See lossless compression
A high-resolution software player, such as media players from Sonic Studio (www.sonicstudio.com) and JRiver (www.jriver.com) are required to play the high-end music, and a good sound card or external digital-to-analog converter (DAC) is required (see D/A converter
and USB DAC
Quality Vs. Convenience
The iPod created a revolution in digital music playback starting in the early 2000s. However, users have sacrificed sound quality for convenience, because the MP3 and AAC formats compress the data. However, to most people, the sound is good enough, especially when listening on tiny earphones. To audiophiles, even CD quality is not sufficient, which is why many aficionados still prefer the pure analog sound of vinyl LP records.
However, there is a choice in audio quality when ripping CDs to MP3 and other formats. The user can choose how much compression is applied to the digital data. The higher the bit rate, the more data are transferred per second. The higher rate means better quality, but the file is larger. See audiophile
, vinyl record
and Apple Lossless
High-resolution music titles such as these are available from the HDtracks website. While sample size is 24 bits on these titles, note the different sampling rates in kHz. The files with 88/24 and 176/24 resolution were taken from DSD masters (see 88.2/24
). (Images courtesy of HDtracks, www.hdtracks.com)
CD Quality and More
Resolution Audio's Cantata is a high-quality CD player as well as a USB analog-to-digital converter (USB DAC) that supports 24-bit samples at 192 kHz. (Image courtesy of Resolution Audio, www.resolutionaudio.com)
Smooth Out the Waveforms
Before conversion to analog, this high-end MOON Evolution CD player from Simaudio reconstructs the CD's 16-bit samples into 32-bit samples to smooth out the sound waves. The unit is also a USB DAC that supports 24-bit samples up to 192 kHz. In this example, digital input #2 is selected. (Image courtesy of Simaudio, Ltd., www.simaudio.com)
Music lovers can also enjoy high-quality audio in portable players such as these from Pono (top) and Astell & Kern (bottom). For more information, visit www.ponomusic.com and www.astellnkern.com. (Image courtesy of PonoMusic.)