[FFmpeg-cvslog] avfilter/avf_showcqt: use frequency domain windowing
Muhammad Faiz
git at videolan.org
Fri Sep 18 18:52:28 CEST 2015
ffmpeg | branch: master | Muhammad Faiz <mfcc64 at gmail.com> | Wed Sep 16 15:24:23 2015 +0700| [5b48dd75d578ae694779d0212cf85f6c84453b7c] | committer: Michael Niedermayer
avfilter/avf_showcqt: use frequency domain windowing
faster initialization and less code
slightly different result computationally from previous
coeffclamp option is ignored
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5b48dd75d578ae694779d0212cf85f6c84453b7c
---
libavfilter/avf_showcqt.c | 136 +++++++++++----------------------------------
1 file changed, 31 insertions(+), 105 deletions(-)
diff --git a/libavfilter/avf_showcqt.c b/libavfilter/avf_showcqt.c
index 39e1c55..7089758 100644
--- a/libavfilter/avf_showcqt.c
+++ b/libavfilter/avf_showcqt.c
@@ -24,8 +24,6 @@
#include "libavutil/channel_layout.h"
#include "libavutil/opt.h"
#include "libavutil/xga_font_data.h"
-#include "libavutil/qsort.h"
-#include "libavutil/time.h"
#include "libavutil/eval.h"
#include "avfilter.h"
#include "internal.h"
@@ -49,7 +47,6 @@
#define SPECTOGRAM_HEIGHT ((VIDEO_HEIGHT-FONT_HEIGHT)/2)
#define SPECTOGRAM_START (VIDEO_HEIGHT-SPECTOGRAM_HEIGHT)
#define BASE_FREQ 20.051392800492
-#define COEFF_CLAMP 1.0e-4
#define TLENGTH_MIN 0.001
#define TLENGTH_DEFAULT "384/f*tc/(384/f+tc)"
#define VOLUME_MIN 1e-10
@@ -59,9 +56,9 @@
"r(1-ld(1)) + b(ld(1))"
typedef struct {
- FFTSample value;
- int index;
-} SparseCoeff;
+ FFTSample *values;
+ int start, len;
+} Coeffs;
typedef struct {
const AVClass *class;
@@ -70,11 +67,9 @@ typedef struct {
FFTComplex *fft_data;
FFTComplex *fft_result;
uint8_t *spectogram;
- SparseCoeff *coeff_sort;
- SparseCoeff *coeffs[VIDEO_WIDTH];
+ Coeffs coeffs[VIDEO_WIDTH];
uint8_t *font_alpha;
char *fontfile; /* using freetype */
- int coeffs_len[VIDEO_WIDTH];
uint8_t fontcolor_value[VIDEO_WIDTH*3]; /* result of fontcolor option */
int64_t frame_count;
int spectogram_count;
@@ -124,10 +119,9 @@ static av_cold void uninit(AVFilterContext *ctx)
av_fft_end(s->fft_context);
s->fft_context = NULL;
for (k = 0; k < VIDEO_WIDTH; k++)
- av_freep(&s->coeffs[k]);
+ av_freep(&s->coeffs[k].values);
av_freep(&s->fft_data);
av_freep(&s->fft_result);
- av_freep(&s->coeff_sort);
av_freep(&s->spectogram);
av_freep(&s->font_alpha);
av_frame_free(&s->outpicref);
@@ -305,14 +299,6 @@ static double b_func(void *p, double x)
return (int)(x*255.0+0.5);
}
-static inline int qsort_sparsecoeff(const SparseCoeff *a, const SparseCoeff *b)
-{
- if (fabsf(a->value) >= fabsf(b->value))
- return 1;
- else
- return -1;
-}
-
static int config_output(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
@@ -325,11 +311,10 @@ static int config_output(AVFilterLink *outlink)
static const char * const expr_fontcolor_func_names[] = { "midi", "r", "g", "b", NULL };
static double (* const expr_funcs[])(void *, double) = { a_weighting, b_weighting, c_weighting, NULL };
static double (* const expr_fontcolor_funcs[])(void *, double) = { midi, r_func, g_func, b_func, NULL };
- int fft_len, k, x, y, ret;
+ int fft_len, k, x, ret;
int num_coeffs = 0;
int rate = inlink->sample_rate;
double max_len = rate * (double) s->timeclamp;
- int64_t start_time, end_time;
int video_scale = s->fullhd ? 2 : 1;
int video_width = (VIDEO_WIDTH/2) * video_scale;
int video_height = (VIDEO_HEIGHT/2) * video_scale;
@@ -344,11 +329,10 @@ static int config_output(AVFilterLink *outlink)
}
s->fft_data = av_malloc_array(fft_len, sizeof(*s->fft_data));
- s->coeff_sort = av_malloc_array(fft_len, sizeof(*s->coeff_sort));
s->fft_result = av_malloc_array(fft_len + 1, sizeof(*s->fft_result));
s->fft_context = av_fft_init(s->fft_bits, 0);
- if (!s->fft_data || !s->coeff_sort || !s->fft_result || !s->fft_context)
+ if (!s->fft_data || !s->fft_result || !s->fft_context)
return AVERROR(ENOMEM);
#if CONFIG_LIBFREETYPE
@@ -359,8 +343,6 @@ static int config_output(AVFilterLink *outlink)
s->font_alpha = NULL;
#endif
- av_log(ctx, AV_LOG_INFO, "Calculating spectral kernel, please wait\n");
- start_time = av_gettime_relative();
ret = av_expr_parse(&tlength_expr, s->tlength, expr_vars, NULL, NULL, NULL, NULL, 0, ctx);
if (ret < 0)
goto eval_error;
@@ -376,22 +358,10 @@ static int config_output(AVFilterLink *outlink)
goto eval_error;
for (k = 0; k < VIDEO_WIDTH; k++) {
- int hlen = fft_len >> 1;
- float total = 0;
- float partial = 0;
double freq = BASE_FREQ * exp2(k * (1.0/192.0));
- double tlen, tlength, volume;
+ double flen, center, tlength, volume;
+ int start, end;
double expr_vars_val[] = { s->timeclamp, s->timeclamp, freq, freq, freq, 0 };
- /* a window function from Albert H. Nuttall,
- * "Some Windows with Very Good Sidelobe Behavior"
- * -93.32 dB peak sidelobe and 18 dB/octave asymptotic decay
- * coefficient normalized to a0 = 1 */
- double a0 = 0.355768;
- double a1 = 0.487396/a0;
- double a2 = 0.144232/a0;
- double a3 = 0.012604/a0;
- double sv_step, cv_step, sv, cv;
- double sw_step, cw_step, sw, cw, w;
tlength = av_expr_eval(tlength_expr, expr_vars_val, NULL);
if (isnan(tlength)) {
@@ -424,75 +394,31 @@ static int config_output(AVFilterLink *outlink)
fontcolor_value += 3;
}
- tlen = tlength * rate;
- s->fft_data[0].re = 0;
- s->fft_data[0].im = 0;
- s->fft_data[hlen].re = (1.0 + a1 + a2 + a3) * (1.0/tlen) * volume * (1.0/fft_len);
- s->fft_data[hlen].im = 0;
- sv_step = sv = sin(2.0*M_PI*freq*(1.0/rate));
- cv_step = cv = cos(2.0*M_PI*freq*(1.0/rate));
- /* also optimizing window func */
- sw_step = sw = sin(2.0*M_PI*(1.0/tlen));
- cw_step = cw = cos(2.0*M_PI*(1.0/tlen));
- for (x = 1; x < 0.5 * tlen; x++) {
- double cv_tmp, cw_tmp;
- double cw2, cw3, sw2;
-
- cw2 = cw * cw - sw * sw;
- sw2 = cw * sw + sw * cw;
- cw3 = cw * cw2 - sw * sw2;
- w = (1.0 + a1 * cw + a2 * cw2 + a3 * cw3) * (1.0/tlen) * volume * (1.0/fft_len);
- s->fft_data[hlen + x].re = w * cv;
- s->fft_data[hlen + x].im = w * sv;
- s->fft_data[hlen - x].re = s->fft_data[hlen + x].re;
- s->fft_data[hlen - x].im = -s->fft_data[hlen + x].im;
-
- cv_tmp = cv * cv_step - sv * sv_step;
- sv = sv * cv_step + cv * sv_step;
- cv = cv_tmp;
- cw_tmp = cw * cw_step - sw * sw_step;
- sw = sw * cw_step + cw * sw_step;
- cw = cw_tmp;
+ /* direct frequency domain windowing */
+ flen = 8.0 * fft_len / (tlength * rate);
+ center = freq * fft_len / rate;
+ start = FFMAX(0, ceil(center - 0.5 * flen));
+ end = FFMIN(fft_len, floor(center + 0.5 * flen));
+ s->coeffs[k].len = end - start + 1;
+ s->coeffs[k].start = start;
+ num_coeffs += s->coeffs[k].len;
+ s->coeffs[k].values = av_malloc_array(s->coeffs[k].len, sizeof(*s->coeffs[k].values));
+ if (!s->coeffs[k].values) {
+ ret = AVERROR(ENOMEM);
+ goto eval_error;
}
- for (; x < hlen; x++) {
- s->fft_data[hlen + x].re = 0;
- s->fft_data[hlen + x].im = 0;
- s->fft_data[hlen - x].re = 0;
- s->fft_data[hlen - x].im = 0;
- }
- av_fft_permute(s->fft_context, s->fft_data);
- av_fft_calc(s->fft_context, s->fft_data);
-
- for (x = 0; x < fft_len; x++) {
- s->coeff_sort[x].index = x;
- s->coeff_sort[x].value = s->fft_data[x].re;
- }
-
- AV_QSORT(s->coeff_sort, fft_len, SparseCoeff, qsort_sparsecoeff);
- for (x = 0; x < fft_len; x++)
- total += fabsf(s->coeff_sort[x].value);
-
- for (x = 0; x < fft_len; x++) {
- partial += fabsf(s->coeff_sort[x].value);
- if (partial > total * s->coeffclamp * COEFF_CLAMP) {
- s->coeffs_len[k] = fft_len - x;
- num_coeffs += s->coeffs_len[k];
- s->coeffs[k] = av_malloc_array(s->coeffs_len[k], sizeof(*s->coeffs[k]));
- if (!s->coeffs[k]) {
- ret = AVERROR(ENOMEM);
- goto eval_error;
- }
- for (y = 0; y < s->coeffs_len[k]; y++)
- s->coeffs[k][y] = s->coeff_sort[x+y];
- break;
- }
+ for (x = start; x <= end; x++) {
+ int sign = (x & 1) ? (-1) : 1;
+ double u = 2.0 * M_PI * (x - center) * (1.0/flen);
+ /* nuttall window */
+ double w = 0.355768 + 0.487396 * cos(u) + 0.144232 * cos(2*u) + 0.012604 * cos(3*u);
+ s->coeffs[k].values[x-start] = sign * volume * (1.0/fft_len) * w;
}
}
av_expr_free(fontcolor_expr);
av_expr_free(volume_expr);
av_expr_free(tlength_expr);
- end_time = av_gettime_relative();
- av_log(ctx, AV_LOG_INFO, "Elapsed time %.6f s (fft_len=%u, num_coeffs=%u)\n", 1e-6 * (end_time-start_time), fft_len, num_coeffs);
+ av_log(ctx, AV_LOG_INFO, "fft_len=%u, num_coeffs=%u\n", fft_len, num_coeffs);
outlink->w = video_width;
outlink->h = video_height;
@@ -552,9 +478,9 @@ static int plot_cqt(AVFilterLink *inlink)
FFTComplex w = {0,0};
FFTComplex l, r;
- for (u = 0; u < s->coeffs_len[x]; u++) {
- FFTSample value = s->coeffs[x][u].value;
- int index = s->coeffs[x][u].index;
+ for (u = 0; u < s->coeffs[x].len; u++) {
+ FFTSample value = s->coeffs[x].values[u];
+ int index = s->coeffs[x].start + u;
v.re += value * s->fft_result[index].re;
v.im += value * s->fft_result[index].im;
w.re += value * s->fft_result[fft_len - index].re;
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