ardour/livetrax
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Micro-optimization: pre-calculate pan-law

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powf() is very expensive to call, and as long as the pan-law
is fixed, there is no need to re-calculate coefficient scale
factor on every update.
This commit is contained in:
Robin Gareus 2021-01-18 15:29:13 +01:00
parent 31691a6ad4
commit c02169a6c8
Signed by: rgareus
GPG Key ID: A090BCE02CF57F04
2 changed files with 19 additions and 4 deletions
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13
libs/panners/1in2out/panner_1in2out.cc
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@ -101,12 +101,15 @@ Panner1in2out::~Panner1in2out ()
void
Panner1in2out::update ()
{
float panR, panL;
#if 0
float const pan_law_attenuation = -3.0f;
float const scale = 2.0f - 4.0f * powf (10.0f, pan_law_attenuation / 20.0f);
#else
float const scale = -0.831783138f;
#endif
panR = _pannable->pan_azimuth_control->get_value ();
panL = 1 - panR;
float const panR = _pannable->pan_azimuth_control->get_value ();
float const panL = 1 - panR;
desired_left = panL * (scale * panL + 1.0f - scale);
desired_right = panR * (scale * panR + 1.0f - scale);
@ -275,8 +278,12 @@ Panner1in2out::distribute_one_automated (AudioBuffer& srcbuf, BufferSet& obufs,
each buffer (output)
*/
#if 0
const float pan_law_attenuation = -3.0f;
const float scale = 2.0f - 4.0f * powf (10.0f, pan_law_attenuation / 20.0f);
#else
float const scale = -0.831783138f;
#endif
for (pframes_t n = 0; n < nframes; ++n) {
float panR = position[n];

10
libs/panners/2in2out/panner_2in2out.cc
View File

@ -184,9 +184,13 @@ Panner2in2out::update ()
}
/* compute target gain coefficients for both input signals */
#if 0
float const pan_law_attenuation = -3.0f;
float const scale = 2.0f - 4.0f * powf (10.0f, pan_law_attenuation / 20.0f);
#else
float const scale = -0.831783138f;
#endif
float panR;
float panL;
@ -408,8 +412,12 @@ Panner2in2out::distribute_one_automated (AudioBuffer& srcbuf, BufferSet& obufs,
* each buffer (output)
*/
#if 0
const float pan_law_attenuation = -3.0f;
const float scale = 2.0f - 4.0f * powf (10.0f, pan_law_attenuation / 20.0f);
#else
float const scale = -0.831783138f;
#endif
for (pframes_t n = 0; n < nframes; ++n) {
float panR;