1. High Resolution Digital Audio

2. Review of vocabulary Prefixes: k = 1,000 Bit = 1 binary digit
M = 1,000,000
G = 1,000,000,000
Bit = 1 binary digit
Byte = 8 bits
Bandwidth = size of a pipe through which data can flow; measured in bps (bits per second)

3. Sampling Rate
An analog signal is “sampled” - i.e. snapshot measurements of its level at given moments in time
Nyquist: you must sample at 2x the highest frequency present in the signal
Nyquist limit = highest frequency you can reproduce without aliasing; equal to ½ the sample rate;
You must have an antialiasing filter to attenuate frequencies above your Nyquist limit
The higher your sampling rate, the higher your Nyquist limit

4. Bit Depth Every sample is encoded into a number
Your computer uses binary numbers;
Each number must be a certain number of bits long
In a 16 bit system, even zero must be a 16 digit number =
Any value between bits must be quantized
More bits = less error; less error = less noise
Defines signal to noise & dynamic range
6 dB per bit

5. Sigma Delta DSD – Direct Stream Digital Different from PCM –
Pulse Density Modulation
Hard to work with in post – Sonoma System
1-bit converter with extremely high sample rate (2.8MHz)
Low bit, high-sample rate converters are the norm
Sometimes 4-bit or 8-bit
“Oversampling” converter design very common
Starts with high SR low bit-depth
Decimated & converted to PCM
64 times 44.1 kHz (DSD64)

6. DXD PCM with Ultra-high sampling rates Merging Technologies Pyramix
352.8 kHz / 24-bit
Merging Technologies Pyramix

7. Can we hear the difference?
In PCM, do higher sampling rates matter?
We can't “hear” above 20 kHz...

8. Aliasing
When a frequency exceeds the Nyquist limit, it is folded back into the audible spectrum
30 kHz becomes 10 kHz
If higher frequencies are not adequately attenuated, this could cause distortion or noise in the signal
Anti-aliasing filters can cause artifacts of their own
Higher sampling rates push Nyquist limit higher
Good anti-aliasing filters make a difference

9. Dither Random noise applied to a signal
Usually represents LSB
There are many kinds of dither
Can be “Noise Shaped”
Suppresses correlated noise
Increases dynamic range
Should be applied anytime there is a conversion from higher bit depth to lower
Should be the very last thing applied to your mix

10. Data Compression Lossy algorithms Lossless algorithms
Mp3; DTS; Dolby AC-3
Perceptual coding
Lossless algorithms
Meridian Lossless Packing
FLAC

11. Delivery Formats DVD-Audio: PCM Capable of 2-ch 96 kHz/24-bit
Or PCM 5.1 surround sound at 44.1 kHz
SACD
Super Audio CD – DSD
Blu-Ray
2 ch: 192 kHz/ 24-bit
5.1 surround: 96 kHz / 24-bit
Also 7.1 and 9.1
Downloads
No more need for a delivery format