Digital Audio

# Digital Audio

## Digital Audio

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##### Presentation Transcript

1. Digital Audio

2. A/D and D/A • A/D=analog to digital conversion. Turing vibration into binary code (mic to recorder or DAW) • Conversion of continuous signal to a discrete one • Continuity to discrete steps • D/A=digital to analog conversion. Turn code into vibration (DAW or recorder to monitors (headphone and speaker)) • Most recording devices (computer or recorder) have both devices

3. Sampling Rate • Measured in KHz • 32KHz, 44.1KHz, 48KHz, 96KHz, 192KHz • How many times per second a waveform is “analyzed” • Measures amplitude over time • Higher the sampling rate the more accurately the sound is reproduced digitally • Higher the sampling rate, more processing in post • Essentially, it deals w/ the highest reproducible frequency • Represented horizontally in digital waveform

4. Nyquist Theorem • In order to reproduce a sound waveform as a digital waveform, the sampling rate must be at least TWICE frequency of of the sound being captured • Human hearing range???... 20KHz • Aliasing=new frequencies appear and distort original signal • Image aliasing...resolution

5. Bit Depth • Aka “quantization” • How amplitude is represented as binary code • Determines the dynamic range • Can capture quieter sounds, louder sounds, and sound with less noise • 1 bit = +6dB of dynamic range • 16 bit resolution= 16 x 6= 96dB of dynamic range • Represented vertically in digital waveform

6. Sampling Rate + Bit Depth • More/less information • Allows for more/less processing • More/less dynamic range • More/less disk space • More/less accurate digital representation • DVD Audio/Blur-ray=96KHz 24 bit • Broadcast audio=48.1KHz 16bit • CD audio=44.1KHz 16 bit

7. Sampling Rate + Bit Depth Cont'd • Bit depth + sampling rate + time = file size • 96KHz is 200% larger than 48KHz • 24bit is 300% larger than 16bit

8. Formats • MP3...NEVER EVER EVER USE THIS! • Compressed to 1/10 the size of a .WAV or .AIFF • Made for sharing • Don't record EVER in this format • Use format for sharing larger files • .WAV = Microsoft's proprietary format • .AIFF = Apple's proprietary format • WAV/AIFF are “lossless audio”