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mathutil: Update FFTCompressor for FFTW3

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This has been due for a while. The last FFTW 2.x release was in 1999.

Note that this does change some of the loops; this has two benefits:
1) The halfcomplex storage order is now explained with a comment.
2) It fixed the special case "don't break a run of bytes for a zero" which
   was never triggering due to the value not being *exactly* 0.0.

I have tested these changes against older FFT-compressed animation .bams
and no noticeable decompression changes are present, so a .bam version
bump is not necessary.
This commit is contained in:
Sam Edwards 2018-02-16 04:42:31 -07:00
parent 5c90f64182
commit ad7669e12a
2 changed files with 91 additions and 38 deletions
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5
makepanda/makepanda.py
View File

@ -648,8 +648,7 @@ if (COMPILER == "MSVC"):
if (PkgSkip("HARFBUZZ")==0):
LibName("HARFBUZZ", GetThirdpartyDir() + "harfbuzz/lib/harfbuzz.lib")
IncDirectory("HARFBUZZ", GetThirdpartyDir() + "harfbuzz/include/harfbuzz")
if (PkgSkip("FFTW")==0): LibName("FFTW", GetThirdpartyDir() + "fftw/lib/rfftw.lib")
if (PkgSkip("FFTW")==0): LibName("FFTW", GetThirdpartyDir() + "fftw/lib/fftw.lib")
if (PkgSkip("FFTW")==0): LibName("FFTW", GetThirdpartyDir() + "fftw/lib/fftw3.lib")
if (PkgSkip("ARTOOLKIT")==0):LibName("ARTOOLKIT",GetThirdpartyDir() + "artoolkit/lib/libAR.lib")
if (PkgSkip("OPENCV")==0): LibName("OPENCV", GetThirdpartyDir() + "opencv/lib/cv.lib")
if (PkgSkip("OPENCV")==0): LibName("OPENCV", GetThirdpartyDir() + "opencv/lib/highgui.lib")
@ -816,7 +815,7 @@ if (COMPILER=="GCC"):
SmartPkgEnable("FFMPEG", ffmpeg_libs, ffmpeg_libs, ("libavformat/avformat.h", "libavcodec/avcodec.h", "libavutil/avutil.h"))
SmartPkgEnable("SWSCALE", "libswscale", "libswscale", ("libswscale/swscale.h"), target_pkg = "FFMPEG", thirdparty_dir = "ffmpeg")
SmartPkgEnable("SWRESAMPLE","libswresample", "libswresample", ("libswresample/swresample.h"), target_pkg = "FFMPEG", thirdparty_dir = "ffmpeg")
SmartPkgEnable("FFTW", "", ("rfftw", "fftw"), ("fftw.h", "rfftw.h"))
SmartPkgEnable("FFTW", "", ("fftw3"), ("fftw.h"))
SmartPkgEnable("FMODEX", "", ("fmodex"), ("fmodex", "fmodex/fmod.h"))
SmartPkgEnable("FREETYPE", "freetype2", ("freetype"), ("freetype2", "freetype2/freetype/freetype.h"))
SmartPkgEnable("HARFBUZZ", "harfbuzz", ("harfbuzz"), ("harfbuzz", "harfbuzz/hb-ft.h"))

124
panda/src/mathutil/fftCompressor.cxx
View File

@ -29,18 +29,14 @@
#undef howmany
#endif
#ifdef PHAVE_DRFFTW_H
#include "drfftw.h"
#else
#include "rfftw.h"
#endif
#include "fftw3.h"
// These FFTW support objects can only be defined if we actually have the FFTW
// library available.
static rfftw_plan get_real_compress_plan(int length);
static rfftw_plan get_real_decompress_plan(int length);
static fftw_plan get_real_compress_plan(int length);
static fftw_plan get_real_decompress_plan(int length);
typedef pmap<int, rfftw_plan> RealPlans;
typedef pmap<int, fftw_plan> RealPlans;
static RealPlans _real_compress_plans;
static RealPlans _real_decompress_plans;
@ -262,20 +258,31 @@ write_reals(Datagram &datagram, const PN_stdfloat *array, int length) {
}
// Now generate the Fourier transform.
double *data = (double *)alloca(length * sizeof(double));
int fft_length = length / 2 + 1;
fftw_complex *fft_bins = (fftw_complex *)alloca(fft_length * sizeof(fftw_complex));
// This is for an in-place transform. It doesn't violate strict aliasing
// rules because &fft_bins[0][0] is still a double pointer. This saves on
// precious stack space.
double *data = &fft_bins[0][0];
int i;
for (i = 0; i < length; i++) {
data[i] = array[i];
}
double *half_complex = (double *)alloca(length * sizeof(double));
rfftw_plan plan = get_real_compress_plan(length);
rfftw_one(plan, data, half_complex);
// Note: This is an in-place DFT. `data` and `fft_bins` are aliases.
fftw_plan plan = get_real_compress_plan(length);
fftw_execute_dft_r2c(plan, data, fft_bins);
// Now encode the numbers, run-length encoded by size, so we only write out
// the number of bits we need for each number.
// Note that Panda3D has conventionally always used FFTW2's halfcomplex
// format for serializing the bins. In short, this means that for an n-length
// FFT, it stores:
// 1) The real components for bins 0 through floor(n/2), followed by...
// 2) The imaginary components for bins floor((n+1)/2)-1 through 1.
// (Imaginary component for bin 0 is never stored, as that's always zero.)
vector_double run;
RunWidth run_width = RW_invalid;
@ -286,8 +293,18 @@ write_reals(Datagram &datagram, const PN_stdfloat *array, int length) {
static const double max_range_16 = 32767.0;
static const double max_range_8 = 127.0;
double scale_factor = get_scale_factor(i, length);
double num = cfloor(half_complex[i] / scale_factor + 0.5);
int bin; // which FFT bin we're storing
int j; // 0=real; 1=imag
if (i < fft_length) {
bin = i;
j = 0;
} else {
bin = length - i;
j = 1;
}
double scale_factor = get_scale_factor(bin, fft_length);
double num = cfloor(fft_bins[bin][j] / scale_factor + 0.5);
// How many bits do we need to encode this integer?
double a = fabs(num);
@ -313,16 +330,30 @@ write_reals(Datagram &datagram, const PN_stdfloat *array, int length) {
// across a single intervening zero, don't interrupt the run just for
// that.
if (run_width == RW_8 && num_width == RW_0) {
if (i + 1 >= length || half_complex[i + 1] != 0.0) {
if (run.back() != 0) {
num_width = RW_8;
}
}
if (num_width != run_width) {
// Now we need to flush the last run.
// First, however, take care of the special case above: if we're
// switching from RW_8 to RW_0, there could be a zero at the end, which
// should be reclaimed into the RW_0 run.
bool reclaimed_zero = (run_width == RW_8 && num_width == RW_0 &&
run.back() == 0);
if (reclaimed_zero) {
run.pop_back();
}
num_written += write_run(datagram, run_width, run);
run.clear();
run_width = num_width;
if (reclaimed_zero) {
run.push_back(0);
}
}
run.push_back(num);
@ -595,14 +626,36 @@ read_reals(DatagramIterator &di, vector_stdfloat &array) {
nassertr(num_read == length, false);
nassertr((int)half_complex.size() == length, false);
int fft_length = length / 2 + 1;
fftw_complex *fft_bins = (fftw_complex *)alloca(fft_length * sizeof(fftw_complex));
int i;
for (i = 0; i < length; i++) {
half_complex[i] *= get_scale_factor(i, length);
for (i = 0; i < fft_length; i++) {
double scale_factor = get_scale_factor(i, fft_length);
// For an explanation of this, see the compression code's comment about the
// halfcomplex format.
fft_bins[i][0] = half_complex[i] * scale_factor;
if (i == 0) {
// First bin doesn't store imaginary component
fft_bins[i][1] = 0.0;
} else if ((i == fft_length - 1) && !(length & 1)) {
// Last bin doesn't store imaginary component with even lengths
fft_bins[i][1] = 0.0;
} else {
fft_bins[i][1] = half_complex[length - i] * scale_factor;
}
}
double *data = (double *)alloca(length * sizeof(double));
rfftw_plan plan = get_real_decompress_plan(length);
rfftw_one(plan, &half_complex[0], data);
// This is for an in-place transform. It doesn't violate strict aliasing
// rules because &fft_bins[0][0] is still a double pointer. This saves on
// precious stack space.
double *data = &fft_bins[0][0];
// Note: This is an in-place DFT. `data` and `fft_bins` are aliases.
fftw_plan plan = get_real_decompress_plan(length);
fftw_execute_dft_c2r(plan, fft_bins, data);
double scale = 1.0 / (double)length;
array.reserve(array.size() + length);
@ -770,14 +823,14 @@ free_storage() {
for (pi = _real_compress_plans.begin();
pi != _real_compress_plans.end();
++pi) {
rfftw_destroy_plan((*pi).second);
fftw_destroy_plan((*pi).second);
}
_real_compress_plans.clear();
for (pi = _real_decompress_plans.begin();
pi != _real_decompress_plans.end();
++pi) {
rfftw_destroy_plan((*pi).second);
fftw_destroy_plan((*pi).second);
}
_real_decompress_plans.clear();
#endif
@ -933,17 +986,18 @@ read_run(DatagramIterator &di, vector_double &run) {
}
/**
* Returns the appropriate scaling for the given position within the
* halfcomplex array.
* Returns the appropriate scaling for the given bin in the FFT output.
*
* The scale factor is the value of one integer in the quantized data. As such,
* greater bins (higher, more noticeable frequencies) have *lower* scaling
* factors, which means greater precision.
*/
double FFTCompressor::
get_scale_factor(int i, int length) const {
int m = (length / 2) + 1;
int k = (i < m) ? i : length - i;
nassertr(k >= 0 && k < m, 1.0);
nassertr(i < length, 1.0);
return _fft_offset +
_fft_factor * pow((double)(m-1 - k) / (double)(m-1), _fft_exponent);
_fft_factor * pow((double)(length - i) / (double)(length), _fft_exponent);
}
/**
@ -997,7 +1051,7 @@ get_compressability(const PN_stdfloat *data, int length) const {
* Returns a FFTW plan suitable for compressing a float array of the indicated
* length.
*/
static rfftw_plan
static fftw_plan
get_real_compress_plan(int length) {
RealPlans::iterator pi;
pi = _real_compress_plans.find(length);
@ -1005,8 +1059,8 @@ get_real_compress_plan(int length) {
return (*pi).second;
}
rfftw_plan plan;
plan = rfftw_create_plan(length, FFTW_REAL_TO_COMPLEX, FFTW_ESTIMATE);
fftw_plan plan;
plan = fftw_plan_dft_r2c_1d(length, NULL, NULL, FFTW_ESTIMATE);
_real_compress_plans.insert(RealPlans::value_type(length, plan));
return plan;
@ -1016,7 +1070,7 @@ get_real_compress_plan(int length) {
* Returns a FFTW plan suitable for decompressing a float array of the
* indicated length.
*/
static rfftw_plan
static fftw_plan
get_real_decompress_plan(int length) {
RealPlans::iterator pi;
pi = _real_decompress_plans.find(length);
@ -1024,8 +1078,8 @@ get_real_decompress_plan(int length) {
return (*pi).second;
}
rfftw_plan plan;
plan = rfftw_create_plan(length, FFTW_COMPLEX_TO_REAL, FFTW_ESTIMATE);
fftw_plan plan;
plan = fftw_plan_dft_c2r_1d(length, NULL, NULL, FFTW_ESTIMATE);
_real_decompress_plans.insert(RealPlans::value_type(length, plan));
return plan;