ref: 64fc74460b0b2141c3eb6a9b82d050cec90c38b3
parent: 8b213ec1fb33d48f9496c56be0e96f57d784e0ed
author: Krzysztof Nikiel <knik@users.sourceforge.net>
date: Sat Oct 21 07:37:49 EDT 2017
midside: better energy inequations
--- a/libfaac/midside.c
+++ b/libfaac/midside.c
@@ -26,7 +26,7 @@
static void midside(CoderInfo *coder, ChannelInfo *channel,
double *sl0, double *sr0, int *mscnt,
int wstart, int wend,
- double mutethr
+ double thrmid, double thrside
)
{int sfb;
@@ -38,9 +38,8 @@
int l, start, end;
double sum, diff;
double enrgs, enrgd, enrgl, enrgr;
- double maxs, maxd, maxl, maxr;
- if (sfb < 1)
+ if (sfb < 1)
goto setms;
start = coder->sfb_offset[sfb];
@@ -47,7 +46,6 @@
end = coder->sfb_offset[sfb + 1];
enrgs = enrgd = enrgl = enrgr = 0.0;
- maxs = maxd = maxl = maxr = 0.0;
for (win = wstart; win < wend; win++)
{double *sl = sl0 + win * BLOCK_LEN_SHORT;
@@ -62,20 +60,13 @@
diff = 0.5 * (lx - rx);
enrgs += sum * sum;
- maxs = max(maxs, fabs(sum));
-
enrgd += diff * diff;
- maxd = max(maxd, fabs(diff));
-
enrgl += lx * lx;
enrgr += rx * rx;
-
- maxl = max(maxl, fabs(lx));
- maxr = max(maxr, fabs(rx));
}
}
- if (min(enrgs, enrgd) < mutethr * max(enrgs, enrgd))
+ if ((min(enrgl, enrgr) * thrmid) >= max(enrgs, enrgd))
{ms = 1;
for (win = wstart; win < wend; win++)
@@ -85,17 +76,15 @@
for (l = start; l < end; l++)
{sum = sl[l] + sr[l];
- diff = sl[l] - sr[l];
- if (enrgs < enrgd)
- sum = 0.0;
- else
- diff = 0.0;
+ diff = 0;
+
sl[l] = 0.5 * sum;
sr[l] = 0.5 * diff;
}
}
}
- if (min(enrgl, enrgr) < mutethr * max(enrgl, enrgr))
+
+ if (min(enrgl, enrgr) <= (thrside * max(enrgl, enrgr)))
{for (win = wstart; win < wend; win++)
{@@ -126,23 +115,27 @@
{int chn;
int usems;
- double mutethr;
static const double thr075 = 0.1885; /* ~0.75dB */
- static const double thrmax = 1.5; /* ~1.76dB */
+ static const double thrmax = 0.5; /* ~1.76dB */
+ double thrmid, thrside;
if (quality > 0.01)
{usems = 1;
- mutethr = thr075 / quality;
- if (mutethr > thrmax)
- mutethr = thrmax;
+ thrmid = thr075 / quality;
+ if (thrmid > thrmax)
+ thrmid = thrmax;
}
else
{usems = 0;
- mutethr = 0.0;
+ thrmid = 0.0;
}
+ thrmid += 1.0;
+ thrside = sqrt(thrmid) - 1.0;
+ thrside *= thrside;
+
for (chn = 0; chn < maxchan; chn++)
{int rch;
@@ -180,7 +173,7 @@
{int end = start + coder->groups.len[group];
midside(coder + chn, channel + chn, s[chn], s[rch], &mscnt,
- start, end, mutethr);
+ start, end, thrmid, thrside);
start = end;
}
skip:;