Bits and Pieces - Bits and Pieces Bits November 6, 2007...

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Unformatted text preview: Bits and Pieces Bits November 6, 2007 Induction 07/24/11 07/24/11 Storage ... completion 2 COMPARE 07/24/11 07/24/11 Storage ... completion 3 Conclusion Some microphones use induction to create Some an electrical signal. an Some speakers use the electrical signal to Some create movement using the reverse of the effect. effect. The result is sound going one way or the The other. other. 07/24/11 07/24/11 Storage ... completion 4 How is MP3 Compression Used? Used? (We will discuss WHAT it is in a (We few minutes) few 07/24/11 07/24/11 Storage ... completion 6 Sound Waves (Music, Speech or Sound even noise) are analog in nature even 07/24/11 07/24/11 Storage ... completion 7 Digitization (Inadequate Sampling) 07/24/11 07/24/11 Storage ... completion 8 2 Bit Approach 07/24/11 07/24/11 Storage ... completion 9 Better Nyquist Sampling Theorem: if all significant frequencies of a signal are less than B and if we sample the signal with a frequency 2B or higher, we can exactly reconstruct the signal. anything sampling rate less than 2B will lose information 07/24/11 07/24/11 Storage ... completion 10 Poor Sampling 07/24/11 07/24/11 Storage ... completion 11 Process Sample 07/24/11 07/24/11 Fourier Transform Compress Storage ... completion Store 12 VE O R EM 07/24/11 07/24/11 Storage ... completion 13 MP3 - Simple Collect a “small” region of a musical signal which Collect is periodic. is Take the Fourier Transform. Remove any frequencies that we can’t hear. Remove frequencies that mask other frequencies. Remove soft frequency components that are Remove drowned out by louder frequencies. drowned Remove frequency ranges that the brain won’t Remove hear anyway. hear 07/24/11 07/24/11 Storage ... completion 14 Digitizing The sampling rate is usually taken to be 44 The kbs. This is twice the frequency that we can hear. hear. The number of BITS requited for this The process depends on the number of bits used to encode each volume. used I really don’t understand much about this! 07/24/11 07/24/11 Storage ... completion 15 MP3 Save what is left In digital form. This is the Save MP3 file. MP3 There is MUCH more than this in the actual There process! process! 07/24/11 07/24/11 Storage ... completion 16 ...
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This note was uploaded on 07/24/2011 for the course MUS 3930 taught by Professor Bindell during the Fall '07 term at University of Central Florida.

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