2019年12月7日 星期六

A-law

A-law 將 signed magnitude 表示的 13-bit 線性語音編碼成 8-bit 值,如下表:
Linear inputCompressed code
XOR 01010101
Linear output
s0000000abcdxs000abcds0000000abcd1
s0000001abcdxs001abcds0000001abcd1
s000001abcdxxs010abcds000001abcd10
s00001abcdxxxs011abcds00001abcd100
s0001abcdxxxxs100abcds0001abcd1000
s001abcdxxxxxs101abcds001abcd10000
s01abcdxxxxxxs110abcds01abcd100000
s1abcdxxxxxxxs111abcds1abcd1000000
x: ignored
十進位二進位segEBI 前EBI 後解碼
3968~4095
...
2048~2175
011111xxxxxxx
...
010000xxxxxxx
11111111111
...
11110000
10101010 (0xAA)
...
10100101 (0xA5)
4032
...
2112
1984~2047
...
1024~1087
0011111xxxxxx
...
0010000xxxxxx
11011101111
...
11100000
10111010 (0xBA)
...
10110101 (0xB5)
2016
...
1056
992~1023
...
512~543
00011111xxxxx
...
00010000xxxxx
10111011111
...
11010000
10001010 (0x8A)
...
10000101 (0x85)
1008
...
528
496~511
...
256~271
000011111xxxx
...
000010000xxxx
10011001111
...
11000000
10011010 (0x9A)
...
10010101 (0x95)
504
...
264
248~255
...
128~135
0000011111xxx
...
0000010000xxx
01110111111
...
10110000
11101010 (0xEA)
...
11100101 (0xE5)
252
...
132
124~127
...
64~67
00000011111xx
...
00000010000xx
01010101111
...
10100000
11111010 (0xFA)
...
11110101 (0xF5)
126
...
66
62, 63
...
32, 33
000000011111x
...
000000010000x
00110011111
...
10010000
11001010 (0xCA)
...
11000101 (0xC5)
63
...
33
30, 31
...
0, 1
000000001111x
...
000000000000x
00010001111
...
10000000
11011010 (0xDA)
...
11010101 (0xD5)
31
...
1
-0, -1
...
-30, -31
100000000000x
...
100000001111x
00000000000
...
00001111
01010101 (0x55)
...
01011010 (0x5A)
-1
...
-31
-32, -33
...
-62, -63
100000010000x
...
100000011111x
00100010000
...
00011111
01000101 (0x45)
...
01001010 (0x4A)
-33
...
-63
-64~-67
...
-124~-127
10000010000xx
...
10000011111xx
01000100000
...
00101111
01111010 (0x7A)
...
01110101 (0x75)
-66
...
-126

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