@ -131,10 +131,10 @@ mdct_alloc_fail:
/** Complex multiply */
# define CMUL(pre, pim, are, aim, bre, bim) \
# define CMUL(pre, pim, are, aim, bre, bim, rshift) \
{ \
pre = ( MUL16 ( are , bre ) - MUL16 ( aim , bim ) ) > > 15 ;
pim = ( MUL16 ( are , bim ) + MUL16 ( bre , aim ) ) > > 15 ;
pre = ( MUL16 ( are , bre ) - MUL16 ( aim , bim ) ) > > rshift ;
pim = ( MUL16 ( are , bim ) + MUL16 ( bre , aim ) ) > > rshift ;
}
@ -195,7 +195,7 @@ static void fft(AC3MDCTContext *mdct, IComplex *z, int ln)
p + + ;
q + + ;
for ( l = nblocks ; l < np2 ; l + = nblocks ) {
CMUL ( tmp_re , tmp_im , mdct - > costab [ l ] , - mdct - > sintab [ l ] , q - > re , q - > im ) ;
CMUL ( tmp_re , tmp_im , mdct - > costab [ l ] , - mdct - > sintab [ l ] , q - > re , q - > im , 15 ) ;
BF ( p - > re , p - > im , q - > re , q - > im ,
p - > re , p - > im , tmp_re , tmp_im ) ;
p + + ;
@ -234,7 +234,7 @@ static void mdct512(AC3MDCTContext *mdct, int32_t *out, int16_t *in)
for ( i = 0 ; i < n4 ; i + + ) {
re = ( ( int ) rot [ 2 * i ] - ( int ) rot [ n - 1 - 2 * i ] ) > > 1 ;
im = - ( ( int ) rot [ n2 + 2 * i ] - ( int ) rot [ n2 - 1 - 2 * i ] ) > > 1 ;
CMUL ( x [ i ] . re , x [ i ] . im , re , im , - mdct - > xcos1 [ i ] , mdct - > xsin1 [ i ] ) ;
CMUL ( x [ i ] . re , x [ i ] . im , re , im , - mdct - > xcos1 [ i ] , mdct - > xsin1 [ i ] , 15 ) ;
}
fft ( mdct , x , mdct - > nbits - 2 ) ;
@ -243,7 +243,7 @@ static void mdct512(AC3MDCTContext *mdct, int32_t *out, int16_t *in)
for ( i = 0 ; i < n4 ; i + + ) {
re = x [ i ] . re ;
im = x [ i ] . im ;
CMUL ( out [ n2 - 1 - 2 * i ] , out [ 2 * i ] , re , im , mdct - > xsin1 [ i ] , mdct - > xcos1 [ i ] ) ;
CMUL ( out [ n2 - 1 - 2 * i ] , out [ 2 * i ] , re , im , mdct - > xsin1 [ i ] , mdct - > xcos1 [ i ] , 0 ) ;
}
}
@ -294,10 +294,26 @@ static void lshift_tab(int16_t *tab, int n, unsigned int lshift)
}
/**
* Right - shift each value in an array of int32_t by a specified amount .
* @ param src input array
* @ param len number of values in the array
* @ param shift right shift amount
*/
static void ac3_rshift_int32_c ( int32_t * src , unsigned int len , unsigned int shift )
{
int i ;
if ( shift > 0 ) {
for ( i = 0 ; i < len ; i + + )
src [ i ] > > = shift ;
}
}
/**
* Normalize the input samples to use the maximum available precision .
* This assumes signed 16 - bit input samples . Exponents are reduced by 9 to
* match the 24 - bit internal precision for MDCT coefficients .
* This assumes signed 16 - bit input samples .
*
* @ return exponent shift
*/
@ -305,18 +321,25 @@ static int normalize_samples(AC3EncodeContext *s)
{
int v = 14 - log2_tab ( s , s - > windowed_samples , AC3_WINDOW_SIZE ) ;
lshift_tab ( s - > windowed_samples , AC3_WINDOW_SIZE , v ) ;
return v - 9 ;
/* +6 to right-shift from 31-bit to 25-bit */
return v + 6 ;
}
/**
* Scale MDCT coefficients from float to fixed - point .
* Scale MDCT coefficients to 25 - bit signed fixed - point .
*/
static void scale_coefficients ( AC3EncodeContext * s )
{
/* scaling/conversion is obviously not needed for the fixed-point encoder
since the coefficients are already fixed - point . */
return ;
int blk , ch ;
for ( blk = 0 ; blk < AC3_MAX_BLOCKS ; blk + + ) {
AC3Block * block = & s - > blocks [ blk ] ;
for ( ch = 0 ; ch < s - > channels ; ch + + ) {
ac3_rshift_int32_c ( block - > mdct_coef [ ch ] , AC3_MAX_COEFS ,
block - > coeff_shift [ ch ] ) ;
}
}
}
Justin
14 years ago
committed by