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authorMax Kellermann <max@duempel.org>2013-12-22 17:39:26 +0100
committerMax Kellermann <max@duempel.org>2013-12-28 18:30:24 +0100
commitafcf0795c44260f54e74ec854297de439e7562c3 (patch)
treef4ec95c5d889d81ec840f83f105a03625f663cb6 /src/pcm/PcmDither.cxx
parent394e2815dbaf0edb8d0f34b6ceab96b58f071ea8 (diff)
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pcm/Volume: improved dithering
Instead of just adding a rectangular random value before shifting back to the normal scale, use the existing PcmDither library.
Diffstat (limited to '')
-rw-r--r--src/pcm/PcmDither.cxx13
1 files changed, 13 insertions, 0 deletions
diff --git a/src/pcm/PcmDither.cxx b/src/pcm/PcmDither.cxx
index f07d0b343..d9d4d28ca 100644
--- a/src/pcm/PcmDither.cxx
+++ b/src/pcm/PcmDither.cxx
@@ -62,6 +62,19 @@ PcmDither::Dither(T sample)
return output >> scale_bits;
}
+template<typename ST, unsigned SBITS, unsigned DBITS>
+inline ST
+PcmDither::DitherShift(ST sample)
+{
+ static_assert(sizeof(ST) * 8 > SBITS, "Source type too small");
+ static_assert(SBITS > DBITS, "Non-positive scale_bits");
+
+ static constexpr ST MIN = -(ST(1) << (SBITS - 1));
+ static constexpr ST MAX = (ST(1) << (SBITS - 1)) - 1;
+
+ return Dither<ST, MIN, MAX, SBITS - DBITS>(sample);
+}
+
template<typename ST, typename DT>
inline typename DT::value_type
PcmDither::DitherConvert(typename ST::value_type sample)