1. Pengantar Multimedia
Data compression

2. Purpose Transmission of images over channels with limited bandwidth
Digital Cinema = 250 Mbit/s
90 minutes movie = 170GB space
Computer tomography
700 MB / examination
Several countries ruled that examination data must be stored for at least 10 years.

3. RLE Run Length Encoding Very simple ABCCCCCCCCDEFGGGG = 17 byte
RLE = ABC8DEFG4 = 9 byte

4. Huffman Uses trie Find each char freq. STMIK AKAKOM = 12 byte (96bit)
S = 1; T = 1; M = 2; I = 1; K = 3; A = 2; O = 1; _ = 1
K A M S1 T1 I O _1

5. K = 00; A = 01; M = 100; S =101; T = 1100; I = 1101; O = 1110; _ = 1111

6. S T M I K A K A K O M K = 00; A = 01; M = 100; S =101; T = 1100;
31 bit
31 / 96 = 32% compression
68 saving
K = 00; A = 01; M = 100; S =101; T = 1100;
I = 1101; O = 1110; _ = 1111

7. LZ 77 (Lempel Ziv )
Look for sequences of characters appearing over and over again
Use Pointers
Teknik Informatika Sistem Informasi
< j , l > (j = jump, l = length)
Pointer usually 2 bytes (16 bit) information

8. Teknik Informatika Sistem Informasi=
Teknik Informatika Sistem <19,7>si
8 bit + 8 bit = 256 jump length
Modification : 16 bits ( , )
12 bits + 4 bit
12 bit jump (long jump, 214 = 4096 distance)
4 bit length (24 = 16 length)