Makes surround_analysis() work in fixed-point
diff --git a/src/opus_multistream_encoder.c b/src/opus_multistream_encoder.c
index bc86489..7cc3237 100644
--- a/src/opus_multistream_encoder.c
+++ b/src/opus_multistream_encoder.c
@@ -179,6 +179,45 @@
}
}
+#if 1
+/* Computes a rough approximation of log2(2^a + 2^b) */
+static opus_val16 logSum(opus_val16 a, opus_val16 b)
+{
+ opus_val16 max;
+ opus_val32 diff;
+ opus_val16 frac;
+ static const opus_val16 diff_table[17] = {
+ QCONST16(0.5000000f, DB_SHIFT), QCONST16(0.2924813f, DB_SHIFT), QCONST16(0.1609640f, DB_SHIFT), QCONST16(0.0849625f, DB_SHIFT),
+ QCONST16(0.0437314f, DB_SHIFT), QCONST16(0.0221971f, DB_SHIFT), QCONST16(0.0111839f, DB_SHIFT), QCONST16(0.0056136f, DB_SHIFT),
+ QCONST16(0.0028123f, DB_SHIFT)
+ };
+ int low;
+ if (a>b)
+ {
+ max = a;
+ diff = SUB32(EXTEND32(a),EXTEND32(b));
+ } else {
+ max = b;
+ diff = SUB32(EXTEND32(b),EXTEND32(a));
+ }
+ if (diff >= QCONST16(8.f, DB_SHIFT))
+ return max;
+#ifdef FIXED_POINT
+ low = SHR32(diff, DB_SHIFT-1);
+ frac = SHL16(diff - SHL16(low, DB_SHIFT-1), 16-DB_SHIFT);
+#else
+ low = floor(2*diff);
+ frac = 2*diff - low;
+#endif
+ return max + diff_table[low] + MULT16_16_Q15(frac, SUB16(diff_table[low+1], diff_table[low]));
+}
+#else
+opus_val16 logSum(opus_val16 a, opus_val16 b)
+{
+ return log2(pow(4, a)+ pow(4, b))/2;
+}
+#endif
+
void surround_analysis(const CELTMode *celt_mode, const void *pcm, opus_val16 *bandLogE, opus_val32 *mem, opus_val32 *preemph_mem,
int len, int overlap, int channels, int rate, opus_copy_channel_in_func copy_channel_in
)
@@ -190,7 +229,6 @@
int pos[8] = {0};
int upsample;
opus_val32 bandE[21];
- opus_val32 maskE[3][21];
opus_val16 maskLogE[3][21];
VARDECL(opus_val32, in);
VARDECL(opus_val16, x);
@@ -202,9 +240,9 @@
channel_pos(channels, pos);
- for (c=0;c<2;c++)
+ for (c=0;c<3;c++)
for (i=0;i<21;i++)
- maskE[c][i] = 0;
+ maskLogE[c][i] = -QCONST16(28.f, DB_SHIFT);
upsample = resampling_factor(rate);
for (c=0;c<channels;c++)
@@ -224,24 +262,23 @@
}
compute_band_energies(celt_mode, freq, bandE, 21, 1, 1<<LM);
- /* FIXME: Figure out how to square bandE[] in fixed-point */
+ amp2Log2(celt_mode, 21, 21, bandE, bandLogE+21*c, 1);
if (pos[c]==1)
{
for (i=0;i<21;i++)
- maskE[0][i] += bandE[i]*bandE[i];
+ maskLogE[0][i] = logSum(maskLogE[0][i], bandLogE[21*c+i]);
} else if (pos[c]==3)
{
for (i=0;i<21;i++)
- maskE[1][i] += bandE[i]*bandE[i];
+ maskLogE[2][i] = logSum(maskLogE[2][i], bandLogE[21*c+i]);
} else if (pos[c]==2)
{
for (i=0;i<21;i++)
{
- maskE[0][i] += HALF32(bandE[i]*bandE[i]);
- maskE[1][i] += HALF32(bandE[i]*bandE[i]);
+ maskLogE[0][i] = logSum(maskLogE[0][i], bandLogE[21*c+i]-QCONST16(.5f, DB_SHIFT));
+ maskLogE[2][i] = logSum(maskLogE[2][i], bandLogE[21*c+i]-QCONST16(.5f, DB_SHIFT));
}
}
- amp2Log2(celt_mode, 21, 21, bandE, bandLogE+21*c, 1);
#if 0
for (i=0;i<21;i++)
printf("%f ", bandLogE[21*c+i]);
@@ -254,16 +291,10 @@
OPUS_COPY(mem+c*overlap, in+len, overlap);
}
for (i=0;i<21;i++)
- maskE[2][i] = MIN32(maskE[0][i],maskE[1][i]);
+ maskLogE[1][i] = MIN32(maskLogE[0][i],maskLogE[2][i]);
for (c=0;c<3;c++)
for (i=0;i<21;i++)
- maskE[c][i] = sqrt(maskE[c][i]*2/(channels-1));
- /* Left mask */
- amp2Log2(celt_mode, 21, 21, &maskE[0][0], &maskLogE[0][0], 1);
- /* Right mask */
- amp2Log2(celt_mode, 21, 21, &maskE[1][0], &maskLogE[2][0], 1);
- /* Centre mask */
- amp2Log2(celt_mode, 21, 21, &maskE[2][0], &maskLogE[1][0], 1);
+ maskLogE[c][i] += QCONST16(.5f, DB_SHIFT)*log2(2.f/(channels-1));
#if 0
for (c=0;c<3;c++)
{