Using measurements on a ruler as an analogy, Matt illustrates how quantization distortion can happen when extremely small samples are rounded off to 0 during quantization.Then he demonstrates how dither noise (added before the quantization step) can eliminate the quantization distortion for the tradeoff of having an analog-like noise floor. Dither is usually done through a DAW automatically and, as long as it's enabled, quantization distortion is very rare.
- If it were not for a technique called dither,…digital audio at very low amplitudes…would run into a problem called quantization distortion.…This mainly happens to low amplitude signals,…which are too small compared to the space…between available quantization levels.…Let me explain.…For example, if we measure this pencil,…which is like a relatively high amplitude signal,…it doesn't matter too much if the measurement…is quantized to six inches or six and an eighth inches.…
The quantization distortion,…that is the difference between the original signal…and the measured value,…is relatively very small.…But at low amplitudes, quantization distortion…can be a big deal.…For example, if we're measuring this paper clip,…which is like a fairly low amplitude signal,…the difference between calling it 3/16 inches…or one-quarter inch is relatively large.…And since the paper clip is actually in between those two,…choosing either value would introduce a fairly large…rounding error relative to the object size.…
Things get even worse as the amplitude drops further.…
The course starts with explanations of what sound really is and how we hear it, including discussions on frequency, amplitude, phase, and psychoacoustics. Matt explores analog audio signal path, explaining connections, gain staging, and metering. Next, he brings the audio signal into the digital domain, discussing analog to digital conversion, digital gain staging, file formats and compression, and dither.
Then the course digs into digital audio workstations (DAWs), explaining the concepts and misconceptions involved in digital recording systems. Matt describes how memory, CPU speed, and storage affect your DAW's performance, as well as how to manage computer resources and understand the plethora of file formats associated with digital recording. He follows with an overview of MIDI: how to generate, store, process, and communicate MIDI data. He wraps up with the audio processors that are often used for mixing in a DAW—including EQ, compressors, reverb, delay, and many others.
- What is sound?
- The three domains of sound: acoustic, analog, and digital
- The analog vs. digital signal paths
- Converting analog audio to digital
- Digital formats and data compression
- Understanding the five types of DAWs
- Recording performances with MIDI
- Mixing and processing audio with EQ, compression, and other effects