MTD2 class 8

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

Bit Depth Color Examples

Each new bit doubles the number of intervals.

20	=1
21	=2
22	=4
23	=8
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
220	=1048576
224	=16777216
232	= 4,294,967,295
264	= 18,446,744,073,709,551,616 = 16 exabytes. That's more than 18 billion billion bytes.

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

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

Premiere Audio Demo

Premiere Audio Demo

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