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Revision as of 22:33, 13 March 2007
Contents
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. |
Color Depth
http://en.wikipedia.org/wiki/Color_depth
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
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
Homework
- Read Chapter 3 in Sound Design for Interactive Media
- Render and Post and link a rought cut of your Story Boards with Audio