On Video
Tuesday, January 30th, 2024My recent obsession with Tristania led me to purchase some music from their last lead singer, Mariangela Demurtas, specifically Dark Ability. I really wanted a physical CD, because physical media, but the shipping was shockingly expensive, so I got a digital download.
Very good it is too: a download in WAV and MP3, and I’ve encoded the WAV to FLAC. Great music, atmospheric and powerfful but relaxing, and different to Tristania but great, nicely recorded, too.
One thing did strike me though: the recordings were 24 bit depth, 48kHz, which is a commonly used standard, but less common for releases, which usually adhere to 16-bit/44.1 kHz (Red Book CD).
This sent me down a bit of a hole: why 44.1, an oddly non-round number? Why, then, 48, a rounder number but suspiciously close to 44.1, so close that in all practical terms, it shouldn’t make any difference?
The answer is video. In the early days of digital audio- in the 70s- the only practical way to record digital audio was on to U-Matic professional video tape, because nothing else had the bandwidth for it, so Sony produced PCM encoders and modified U-Matic video tape transports for this reason. Both 44.1 and 48kHaz are chosen as being (a) above the Nyquist frequency for human hearing and (b) not be too inconvenient to encode into TV frames, and both have been engineering standards since. 48 is more commonly used for matching to video as the rates line up with both PAL and NTSC video frame rates without trickery.