mirror of https://github.com/mpv-player/mpv
75 lines
1.7 KiB
C
75 lines
1.7 KiB
C
// code from xanim sources...
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// (I hope that not hurt copyright :o)
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#define xaLONG long
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#define xaULONG unsigned long
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#define xaBYTE char
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#define xaUBYTE unsigned char
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//xaULONG long xa_alaw_2_sign[256];
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xaULONG xa_alaw_2_sign[256];
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xaULONG xa_ulaw_2_sign[256];
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/*
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** This routine converts from ulaw to 16 bit linear.
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**
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** Craig Reese: IDA/Supercomputing Research Center
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** 29 September 1989
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**
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** References:
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** 1) CCITT Recommendation G.711 (very difficult to follow)
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** 2) MIL-STD-188-113,"Interoperability and Performance Standards
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** for Analog-to_Digital Conversion Techniques,"
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** 17 February 1987
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**
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** Input: 8 bit ulaw sample
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** Output: signed 16 bit linear sample
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*/
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xaLONG XA_uLaw_to_Signed( ulawbyte )
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xaUBYTE ulawbyte;
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{
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static int exp_lut[8] = { 0, 132, 396, 924, 1980, 4092, 8316, 16764 };
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int sign, exponent, mantissa, sample;
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ulawbyte = ~ ulawbyte;
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sign = ( ulawbyte & 0x80 );
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exponent = ( ulawbyte >> 4 ) & 0x07;
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mantissa = ulawbyte & 0x0F;
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sample = exp_lut[exponent] + ( mantissa << ( exponent + 3 ) );
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if ( sign != 0 ) sample = -sample;
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return sample;
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}
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void Gen_uLaw_2_Signed()
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{ xaULONG i;
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for(i=0;i<256;i++)
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{ xaUBYTE data = (xaUBYTE)(i);
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xaLONG d = XA_uLaw_to_Signed( data );
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xa_ulaw_2_sign[i] = (xaULONG)((xaULONG)(d) & 0xffff);
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}
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}
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void Gen_aLaw_2_Signed()
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{ xaULONG i;
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for(i=0;i<256;i++)
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{ xaUBYTE data = (xaUBYTE)(i);
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xaLONG d, t, seg;
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data ^= 0x55;
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t = (data & 0xf) << 4;
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seg = (data & 0x70) >> 4;
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if (seg == 0) t += 8;
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else if (seg == 1) t += 0x108;
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else { t += 108; t <<= seg - 1; }
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d = (data & 0x80)?(t):(-t);
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xa_alaw_2_sign[i] = (xaULONG)((xaULONG)(d) & 0xffff);
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}
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}
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