From f284d28d5306114e9badc9077835683e541420e0 Mon Sep 17 00:00:00 2001 From: Hans Baier Date: Wed, 10 Jun 2009 00:03:28 +0000 Subject: libardour: * Add basic classes for later support of multiple interpolation algorithms for varispeed * Add unit tests: Test which shows how the varispeed implementation in diskstream is broken. git-svn-id: svn://localhost/ardour2/branches/3.0@5144 d708f5d6-7413-0410-9779-e7cbd77b26cf --- libs/ardour/ardour/interpolation.h | 49 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 libs/ardour/ardour/interpolation.h (limited to 'libs/ardour/ardour/interpolation.h') diff --git a/libs/ardour/ardour/interpolation.h b/libs/ardour/ardour/interpolation.h new file mode 100644 index 0000000000..09ae242490 --- /dev/null +++ b/libs/ardour/ardour/interpolation.h @@ -0,0 +1,49 @@ +#include +//#include "ardour/types.h" + +typedef float Sample; +#define nframes_t uint32_t + +// 40.24 fixpoint math +#define FIXPOINT_ONE 0x1000000 + +class Interpolation { + protected: + /// speed in fixed point math + uint64_t phi; + + /// target speed in fixed point math + uint64_t target_phi; + + uint64_t last_phase; + + // Fixed point is just an integer with an implied scaling factor. + // In 40.24 the scaling factor is 2^24 = 16777216, + // so a value of 10*2^24 (in integer space) is equivalent to 10.0. + // + // The advantage is that addition and modulus [like x = (x + y) % 2^40] + // have no rounding errors and no drift, and just require a single integer add. + // (swh) + + static const int64_t fractional_part_mask = 0xFFFFFF; + static const Sample binary_scaling_factor = 16777216.0f; + + public: + Interpolation () : phi (FIXPOINT_ONE), target_phi (FIXPOINT_ONE), last_phase (0) {} + + void set_speed (double new_speed) { + target_phi = (uint64_t) (FIXPOINT_ONE * fabs(new_speed)); + phi = target_phi; + } + + uint64_t get_phi () const { return phi; } + uint64_t get_target_phi () const { return target_phi; } + uint64_t get_last_phase () const { return last_phase; } + + virtual nframes_t interpolate (nframes_t nframes, Sample* input, Sample* output) = 0; +}; + +class LinearInterpolation : public Interpolation { + public: + nframes_t interpolate (nframes_t nframes, Sample* input, Sample* output); +}; -- cgit v1.2.3