EECS 1520 Lecture Notes - Lecture 4: Moving Picture Experts Group, Scalable Vector Graphics, Rgb Color Model

• School: York University
• Department: Electrical Engineering and Computer Science
• Course: EECS 1520
• Professor: Steven Castellucci

Document Summary

Microscope is a transducer, converting audio (sound waves) to electrical signals. Digitizing sound involves taking samples (measurements) at fixed rate (sampling rate) Low sa(cid:373)pli(cid:374)g (cid:396)ate (cid:396)ep(cid:396)odu(cid:272)es as sou(cid:374)d (cid:894)(cid:396)ed(cid:895) that does(cid:374)"t (cid:373)at(cid:272)h o(cid:396)igi(cid:374)al f(cid:396)e(cid:395)ue(cid:374)(cid:272)(cid:455) (cid:894)(cid:271)lue(cid:895) Each sample is fixed size called bit depth. Combining bit depth & sampling rate gives bit rate. Higher bit rate=better quality = larger file size. Range of human hearing: 20 hz 20 khz: nyquist-shannon theorem recommends sampling rate approx. 16 bits bit depth (per channel, stereo has 2 channels) Uncompressed audio typically saved in a . wav format. Reduce bit rate (less accurate reproduction of the original) Compression & decompression algorithms for audio (and video) Po(cid:396)t(cid:373)a(cid:374)teau (cid:894)wo(cid:396)d (cid:272)o(cid:373)(cid:271)i(cid:374)atio(cid:374)(cid:895) of (cid:862)(cid:272)ode(cid:396)(cid:863) & (cid:862)de(cid:272)ode(cid:396)(cid:863) o(cid:396) (cid:894)as i(cid:374) this (cid:272)ase(cid:895) (cid:862)(cid:272)o(cid:373)p(cid:396)esso(cid:396)(cid:863) & (cid:862)de(cid:272)o(cid:373)p(cid:396)esso(cid:396) Lossless, using a combination of run-length and huffman encoding. Mp3 (moving pictures experts group, audio layer 3) Lossy, with a compression ratio around 13% [reference: uses psychoacoustics, huffman encoding, and lower bit rates.