1

Technology / Why Does Standard Definition Video Look Better On CRTs Than It Does On HDTVs?

« on: 06/09/2021 06:09:48 »

I always noticed that Standard Definition video (from, say, VHS tapes) played on CRTs looks clearer than it does when the same material is played on HDTVs (either directly from VHS or after being transferred to DVD-Rs).

I've heard people make the general comment that the high resolution of HDTVs can "reveal limitations of the Standard Definition source," but this doesn't explain the additional blurring and artifacts one can see.

If the pixel shape of CRTs is rectangular and HDTVs have smaller, square pixels, I'm not sure why each CRT pixel could not be represented by a group of square HD pixels in an oblong shape that matches the original rectangle, without creating additional artifacts in the conversion.

2

Technology / Why Does Changing The Speed Of Digital Audio Change The Pitch?

« on: 23/02/2018 08:16:46 »

As a music producer and former DJ, I've never been able to wrap my brain around why the pitch control on the first DJ CD players behaved the same way as the pitch control on analog turntables.

That is, DJ turntables like the Technics 1200 included a pitch slider that changed the speed of the platter. Because the grooves in vinyl are direct representations of soundwaves that vibrate the needle, causing the grooves of the record to pass under the needle at a slower rate, say, decreases both the tempo of the music and the pitch because the individual vibrations of the needle happen more slowly, ultimately reproducing a lower frequency soundwave from the speaker.

However the information stored on CDs is digital—it only consists of 1s and 0s. That binary information describes the soundwave of the music at a given moment...44100 times per second in fact. When DJ CD players appeared on the market, I was surprised to find that the sliders affected the pitch of the music—and not just the tempo—because slowing the rotation of a CD should simply cause the 1s and 0s to be read with longer spaces in between. I see how this would slow the tempo, but how could a digital representation of audio change pitch unless the numbers themselves changed?

In time, DJ CD players (and digital audio workstations) have implemented time stretching capabilities that allow the user to make the pitch remain constant while the audio is slowed or sped up. This is achieved by repeating or deleting tiny snippets of sound. I understand why that processing is necessary, but I still can't wrap my brain around the basic fact that slowing the compact disc's read rate would change the pitch of the audio!