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Scale floats directly to 32-bit integer values

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Rather than scaling to a 25-bit integer and shifting for the extra 7 bits. This
should improve precision for values closer to 0.
This commit is contained in:
Chris Robinson
2019-03-25 22:52:15 -07:00
parent 0a4d1c858e
commit a57116f788
2 changed files with 7 additions and 7 deletions
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Alc/alu.cpp
+5 -5
View File
@@ -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)); }
Alc/converter.cpp
+2 -2
View File
@@ -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)