eden-emu/opus
19
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Increasing the temporal resolution of transients

Browse source 
Apply a one-level Haar transform (or Hadamard) on each short MDCT
to nearly double the time-domain resolution.
This commit is contained in:
Jean-Marc Valin 2010-05-21 15:44:06 -04:00
parent 9f89cab6ec
commit 791cfe1f0a
1 changed files with 35 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

37
libcelt/bands.c
View file

@ -452,6 +452,19 @@ static void deinterleave_vector(celt_norm *X, int N0, int stride)
RESTORE_STACK; RESTORE_STACK;
} }
static void haar1(celt_norm *X, int N0, int stride)
{
int i, j;
N0 >>= 1;
for (i=0;i<stride;i++)
for (j=0;j<N0;j++)
{
celt_norm tmp = X[stride*2*j+i];
X[stride*2*j+i] = MULT16_16_Q15(QCONST16(.7070678f,15), X[stride*2*j+i] + X[stride*(2*j+1)+i]);
X[stride*(2*j+1)+i] = MULT16_16_Q15(QCONST16(.7070678f,15), tmp - X[stride*(2*j+1)+i]);
}
}
/* This function is responsible for encoding and decoding a band for both /* This function is responsible for encoding and decoding a band for both
the mono and stereo case. Even in the mono case, it can split the band the mono and stereo case. Even in the mono case, it can split the band
in two and transmit the energy difference with the two half-bands. It in two and transmit the energy difference with the two half-bands. It
@ -466,19 +479,33 @@ static void quant_band(int encode, const CELTMode *m, int i, celt_norm *X, celt_
int imid=0, iside=0; int imid=0, iside=0;
int N0=N; int N0=N;
int N_B=N; int N_B=N;
int N_B0;
int spread0=spread; int spread0=spread;
int do_haar = 0;
if (spread) if (spread)
N_B /= spread; N_B /= spread;
N_B0 = N_B;
split = stereo = Y != NULL; split = stereo = Y != NULL;
if (!stereo && spread>1 && level==0) if (!stereo && spread>1 && level==0)
{ {
if ((N_B&1) == 0)
{
spread <<= 1;
N_B >>= 1;
do_haar = 1;
if (encode) if (encode)
deinterleave_vector(X, N_B, spread); haar1(X, N_B0, spread0);
if (lowband) if (lowband)
deinterleave_vector(lowband, N_B, spread); haar1(lowband, N_B0, spread0);
spread0 = spread;
}
if (encode)
deinterleave_vector(X, N_B, spread0);
if (lowband)
deinterleave_vector(lowband, N_B, spread0);
} }
/* If we need more than 32 bits, try splitting the band in two. */ /* If we need more than 32 bits, try splitting the band in two. */
@ -752,6 +779,12 @@ static void quant_band(int encode, const CELTMode *m, int i, celt_norm *X, celt_
interleave_vector(X, N_B, spread0); interleave_vector(X, N_B, spread0);
if (lowband) if (lowband)
interleave_vector(lowband, N_B, spread0); interleave_vector(lowband, N_B, spread0);
if (do_haar)
{
haar1(X, N_B0, spread0>>1);
if (lowband)
haar1(lowband, N_B0, spread0>>1);
}
} }
if (lowband_out && !stereo) if (lowband_out && !stereo)