# MTD2 class 8

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## In Class

• Audio Effects Presentations
• Intro to digital theory
• Rendering in Premiere

## Digital Theory

Word of the Day Analog How stuff works - How Analog and Digital Recording Works

Analog vs. Digital the arguments in a nutshell

 Analog Digital Good Infinite dynamic quantization (infinite resolution) Quantization error fix - more bit depth/oversampling Good? - The warming effects 'we're used' to from tape compression. Good?-'Perfect' reproduction of high frequencies - 'soundz harsh fix - 'using warm-sounding mikes and preamps (tubes)' Bad - Tape noise and generation loss Good - 'no generation loss' Bad - 'Cheap recordings sound cheap' Good - 'cheap recordings sound good but digital'

* 'anything in quotes is what I like to call an opinion

Other Opinions

analog winner http://www.segall.com/atr.html

analog winner http://www.digido.com/analog_versus_digital.html

comparison http://www.outersound.com/osu/recording/

ana-dig.html Number Systems

 Hexadecimal Base 16 Decimal Base 10 Octal Base 8 Binary Base 2 0 0 0 0000 1 1 1 0001 2 2 2 0010 3 3 3 0011 4 4 4 0100 5 5 5 0101 6 6 6 0110 7 7 7 0111 8 8 10 1000 9 9 11 1001 A 10 12 1010 B 11 13 1011 C 12 14 1100 D 13 15 1101 E 14 16 1110 F 15 17 1111

## Binary Numbers

As Humans we use a 10 base numbering system. For machines this numbering system is impractical.

Gottfried Willheml von Leibnitz devised the binary number system in 1679

Converting Binary Numbers

Binary->Decimal

```   110102 = (1 * 24) + (1 * 23) + (0 * 22) + (1 * 21) + (0 * 20) = 1610 + 810 +  0 + 210 + 0 = 2610
```

Dividing by two

 integer remainder binary # 26 26/2 0 0 13/2 1 1 0 6/2 0 0 1 0 3/2 1 1 0 1 0 1/2 1 1 1 0 1 0 0/2 that's it kids

for more info see Dr. Dave's Class readings (i believe it's in week 2)Daves text

Base2

Each new bit doubles the number of intervals.

 20 =1 monochrome, often black and white 21 =2 22 =4 23 =8 Most early color Unix workstations, VGA at low resolution, Super VGA, AGA http://en.wikipedia.org/wiki/Web_colors#Web-safe_colors 24 =16 25 =32 26 =64 27 =128 28 =256 29 =512 210 =1024 2 11 =2048 212 =4096 213 =8192 214 =16384 215 =32768 216 =65536 "thousands of colors" on Macintosh 220 =1048576 224 =16777216 Truecolor or "millions of colors" on Macintosh systems 232 = 4,294,967,295 refers to 24-bit color (Truecolor) with an additional 8 bits 264 = 18,446,744,073,709,551,616 = 16 exabytes. That's more than 18 billion billion bytes.

## Large Bit Names

 Name Abbr. Size Kilo K 2^10 = 1,024 Mega M 2^20 = 1,048,576 Giga G 2^30 = 1,073,741,824 Tera T 2^40 = 1,099,511,627,776 Peta P 2^50 = 1,125,899,906,842,624 Exa E 2^60 = 1,152,921,504,606,846,976 Zetta Z 2^70 = 1,180,591,620,717,411,303,424 Yotta Y 2^80 = 1,208,925,819,614,629,174,706,176

## Binary Math

OPTIONAL

Binary Math http://www.ibiblio.org/obp/electricCircuits/Digital/DIGI_2.html What can one byte (8 bits) store? 2^7 2^6 2^5 2^4 2^3 2^2 2^1 2^0 1 1 1 1 1 1 1 1 128 64 32 16 8 4 2 1 128+64+32+16+8+4+2+1 = 255

What about negative numbers? Signed Magnitude

Use the first bit as the equivalent of a +/- sign.

http://www.math.grin.edu/~rebelsky/Courses/152/97F/Readings/student-binary.html 510 in 8 bit binary 00000101

-510 in 8 bit binary Signed Magnitude 10000101 (make sure that the circuit knows you are using singed magnitude otherwise this could be interpreted as 113)

Now what can one byte (8 bits) store? +/- 2^6 2^5 2^4 2^3 2^2 2^1 2^0 0 1 1 1 1 1 1 1 + 64 32 16 8 4 2 1 64+32+16+8+4+2+1 = 127 or +/- 2^6 2^5 2^4 2^3 2^2 2^1 2^0 1 1 1 1 1 1 1 1 - 64 32 16 8 4 2 1 -64+32+16+8+4+2+1 = -127

### One's Compliment

One's Compliment uses regular binary numbers to represent positive numbers. To make that number negative you just flip all the bits from 1 to 0 or 0 to 1. 510 in 8 bit binary 00000101

-510 in 8 bit binary One's Compliment 11111010

### Two's Compliment

Same as One's Compliment bit add one to negative numbers 510 in 8 bit binary 00000101

-510 in 8 bit binary Two's Compliment 11111011

To figure out the sign of the answer we must check the MSB (most significant bit).If MSB is 0 number is positive, interpret normally If MSB is 1 number is negative

```   * complement all bits
* add 1
* interpret as negative number
```

## Sampling theory

sampling process

Bit Depth

over 24 bit used mainly for internal processing and really high end audio equipment 24 bit Professional recording and internal processing 16 bit CD quality audio (not so good for processing) 8 bit Smaller size used for consumer voice stuff and multimedia

## Sampling Rates

Some Common Sampling Rates

 192kHz Professional recording and new fancy sound cards 96kHz Professional recording (New CD/DVD format) 48 kHz Professional recording (found mainly on DAT recorders used for film) 44.1 kHz CD quality Audio 22 kHz Multimedia/ Games 11 kHz Multimedia/ Games

File Size per Sampling rate and Bit Depth

 Sample Rate Bit Width File Size per minute 96 kHz 24-bit Stereo 33.0 MB 44.1 kHz 16-bit Stereo 10.5 MB 44.1 kHz 16-bit Mono 5.3 MB 44.1 kHz 8-bit Stereo 5.3 MB 44.1 kHz 8-bit Mono 2.6 MB 22 kHz 16-bit Stereo 5.3 MB 22 kHz 16-bit Mono 2.6 MB 22 kHz 8-bit Stereo 2.6 MB 22 kHz 8-bit Mono 1.3 MB 11 kHz 16-bit Stereo 2.6 MB 11 kHz 16-bit Mono 1.3 MB 11 kHz 8-bit Stereo 1.3 MB 11 kHz 8-bit Mono 660 KB
```  Note : Dropping the Sampling Rate or Bit Depth by half leads to half the file size
```

File formats

 name ext. info aiff .aif audio interchange file format (mac native) supports markers and regions sd2 .sd2 sound designer 2 (digidesign native) supports markers and regions wave .wav wave file (Microsoft) many different formats most support markerz and regions au-law .au or .aul au-law file (unix native) supports compression RAM .ram or .ra Real audio File supports compression and streaming Mpeg3 .mp3 Mpeg layer 3 supports variable compression and streaming (AMP) AAC .aac Mpeg2 Advanced Audio Coding AC-3 standard NEW not supported yet http://www.execpc.com/%7Ereal/aac/index.html MIDI .mid not and audio format Modular (MOD) .mod kinda an audio format (used mainly for games) ASF wmv .asf .wmv windows Media and Advanced Streaming Format Microsoft supports variable compression streaming video encryption

CD Formats

• RedBook Audio standard CD audio format
• CDROM-XA (eXtended Archetecture) audio and data

## Homework

1. Read Chapter 3 in Sound Design for Interactive Media
2. Render and Post and link a rought cut of your Story Boards with Audio