diff options
| author | Chris Robinson <[email protected]> | 2019-03-25 22:52:15 -0700 |
|---|---|---|
| committer | Chris Robinson <[email protected]> | 2019-03-25 22:52:15 -0700 |
| commit | a57116f7888a0fdbdac9ed01ce8237c8296a2f65 (patch) | |
| tree | 5a8816946948c6c3b5d1e4020a58c5d1ea31348b /Alc | |
| parent | 0a4d1c858ec21b948838f5e9b464b5534d497bca (diff) | |
Scale floats directly to 32-bit integer values
Rather than scaling to a 25-bit integer and shifting for the extra 7 bits. This
should improve precision for values closer to 0.
Diffstat (limited to 'Alc')
| -rw-r--r-- | Alc/alu.cpp | 10 | ||||
| -rw-r--r-- | Alc/converter.cpp | 4 |
2 files changed, 7 insertions, 7 deletions
diff --git a/Alc/alu.cpp b/Alc/alu.cpp index 0e91844b..6abc26e1 100644 --- a/Alc/alu.cpp +++ b/Alc/alu.cpp @@ -1587,12 +1587,12 @@ template<> inline ALfloat SampleConv(ALfloat val) noexcept { return val; } template<> inline ALint SampleConv(ALfloat val) noexcept { - /* Floats have a 23-bit mantissa. There is an implied 1 bit in the mantissa - * along with the sign bit, giving 25 bits total, so [-16777216, +16777216] - * is the max value a normalized float can be scaled to before losing - * precision. + /* Floats have a 23-bit mantissa, plus an implied 1 bit and a sign bit. + * This means a normalized float has at most 25 bits of signed precision. + * When scaling and clamping for a signed 32-bit integer, these following + * values are the best a float can give. */ - return fastf2i(clampf(val*16777216.0f, -16777216.0f, 16777215.0f))<<7; + return fastf2i(clampf(val*2147483648.0f, -2147483648.0f, 2147483520.0f)); } template<> inline ALshort SampleConv(ALfloat val) noexcept { return fastf2i(clampf(val*32768.0f, -32768.0f, 32767.0f)); } diff --git a/Alc/converter.cpp b/Alc/converter.cpp index 884a98da..5535fd42 100644 --- a/Alc/converter.cpp +++ b/Alc/converter.cpp @@ -22,7 +22,7 @@ template<> inline ALfloat LoadSample<DevFmtByte>(DevFmtTypeTraits<DevFmtByte>::T template<> inline ALfloat LoadSample<DevFmtShort>(DevFmtTypeTraits<DevFmtShort>::Type val) { return val * (1.0f/32768.0f); } template<> inline ALfloat LoadSample<DevFmtInt>(DevFmtTypeTraits<DevFmtInt>::Type val) -{ return (val>>7) * (1.0f/16777216.0f); } +{ return val * (1.0f/2147483648.0f); } template<> inline ALfloat LoadSample<DevFmtFloat>(DevFmtTypeTraits<DevFmtFloat>::Type val) { return val; } @@ -68,7 +68,7 @@ inline typename DevFmtTypeTraits<T>::Type StoreSample(ALfloat); template<> inline ALfloat StoreSample<DevFmtFloat>(ALfloat val) { return val; } template<> inline ALint StoreSample<DevFmtInt>(ALfloat val) -{ return fastf2i(clampf(val*16777216.0f, -16777216.0f, 16777215.0f))<<7; } +{ return fastf2i(clampf(val*2147483648.0f, -2147483648.0f, 2147483520.0f)); } template<> inline ALshort StoreSample<DevFmtShort>(ALfloat val) { return fastf2i(clampf(val*32768.0f, -32768.0f, 32767.0f)); } template<> inline ALbyte StoreSample<DevFmtByte>(ALfloat val) |