[FFmpeg-cvslog] avfilter/avf_showspectrum: implement zoom mode
Paul B Mahol
git at videolan.org
Fri Oct 5 00:53:18 EEST 2018
ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Thu Oct 4 23:40:02 2018 +0200| [196dd13c76c213e79541c3a692873cdd59c0efa6] | committer: Paul B Mahol
avfilter/avf_showspectrum: implement zoom mode
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=196dd13c76c213e79541c3a692873cdd59c0efa6
---
doc/filters.texi | 6 ++
libavfilter/avf_showspectrum.c | 178 +++++++++++++++++++++++++++++++++++------
2 files changed, 159 insertions(+), 25 deletions(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index 19004f233f..d082b8dc13 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -20719,6 +20719,12 @@ Set which data to display. Can be @code{magnitude}, default or @code{phase}.
@item rotation
Set color rotation, must be in [-1.0, 1.0] range.
Default value is @code{0}.
+
+ at item start
+Set start frequency from which to display spectrogram. Default is @code{0}.
+
+ at item stop
+Set stop frequency to which to display spectrogram. Default is @code{0}.
@end table
The usage is very similar to the showwaves filter; see the examples in that
diff --git a/libavfilter/avf_showspectrum.c b/libavfilter/avf_showspectrum.c
index 856c2c37b5..38d0a9d768 100644
--- a/libavfilter/avf_showspectrum.c
+++ b/libavfilter/avf_showspectrum.c
@@ -62,16 +62,20 @@ typedef struct ShowSpectrumContext {
int scale;
float saturation; ///< color saturation multiplier
float rotation; ///< color rotation
+ int start, stop; ///< zoom mode
int data;
int xpos; ///< x position (current column)
FFTContext **fft; ///< Fast Fourier Transform context
+ FFTContext **ifft; ///< Inverse Fast Fourier Transform context
int fft_bits; ///< number of bits (FFT window size = 1<<fft_bits)
FFTComplex **fft_data; ///< bins holder for each (displayed) channels
+ FFTComplex **fft_scratch; ///< scratch buffers
float *window_func_lut; ///< Window function LUT
float **magnitudes;
float **phases;
int win_func;
int win_size;
+ int buf_size;
double win_scale;
float overlap;
float gain;
@@ -148,6 +152,8 @@ static const AVOption showspectrum_options[] = {
{ "magnitude", NULL, 0, AV_OPT_TYPE_CONST, {.i64=D_MAGNITUDE}, 0, 0, FLAGS, "data" },
{ "phase", NULL, 0, AV_OPT_TYPE_CONST, {.i64=D_PHASE}, 0, 0, FLAGS, "data" },
{ "rotation", "color rotation", OFFSET(rotation), AV_OPT_TYPE_FLOAT, {.dbl = 0}, -1, 1, FLAGS },
+ { "start", "start frequency", OFFSET(start), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT32_MAX, FLAGS },
+ { "stop", "stop frequency", OFFSET(stop), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT32_MAX, FLAGS },
{ NULL }
};
@@ -245,11 +251,21 @@ static av_cold void uninit(AVFilterContext *ctx)
av_fft_end(s->fft[i]);
}
av_freep(&s->fft);
+ if (s->ifft) {
+ for (i = 0; i < s->nb_display_channels; i++)
+ av_fft_end(s->ifft[i]);
+ }
+ av_freep(&s->ifft);
if (s->fft_data) {
for (i = 0; i < s->nb_display_channels; i++)
av_freep(&s->fft_data[i]);
}
av_freep(&s->fft_data);
+ if (s->fft_scratch) {
+ for (i = 0; i < s->nb_display_channels; i++)
+ av_freep(&s->fft_scratch[i]);
+ }
+ av_freep(&s->fft_scratch);
if (s->color_buffer) {
for (i = 0; i < s->nb_display_channels; i++)
av_freep(&s->color_buffer[i]);
@@ -301,6 +317,106 @@ static int query_formats(AVFilterContext *ctx)
return 0;
}
+static int run_channel_fft(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
+{
+ ShowSpectrumContext *s = ctx->priv;
+ AVFilterLink *inlink = ctx->inputs[0];
+ const float *window_func_lut = s->window_func_lut;
+ AVFrame *fin = arg;
+ const int ch = jobnr;
+ int n;
+
+ /* fill FFT input with the number of samples available */
+ const float *p = (float *)fin->extended_data[ch];
+
+ for (n = 0; n < s->win_size; n++) {
+ s->fft_data[ch][n].re = p[n] * window_func_lut[n];
+ s->fft_data[ch][n].im = 0;
+ }
+
+ if (s->stop) {
+ double theta, phi, psi, a, b, S, c;
+ FFTComplex *g = s->fft_data[ch];
+ FFTComplex *h = s->fft_scratch[ch];
+ int L = s->buf_size;
+ int N = s->win_size;
+ int M = s->win_size;
+
+ phi = 2.0 * M_PI * (s->stop - s->start) / (double)inlink->sample_rate / (s->win_size - 1);
+ theta = 2.0 * M_PI * s->start / (double)inlink->sample_rate;
+
+ for (int n = 0; n < s->win_size; n++) {
+ h[n].re = cos(n * n / 2.0 * phi);
+ h[n].im = sin(n * n / 2.0 * phi);
+ }
+
+ for (int n = M; n < L; n++) {
+ h[n].re = 0.0;
+ h[n].im = 0.0;
+ }
+
+ for (int n = L - N; n < L; n++) {
+ h[n].re = cos((L - n) * (L - n) / 2.0 * phi);
+ h[n].im = sin((L - n) * (L - n) / 2.0 * phi);
+ }
+
+ for (int n = 0; n < N; n++) {
+ g[n].re = s->fft_data[ch][n].re;
+ g[n].im = s->fft_data[ch][n].im;
+ }
+
+ for (int n = N; n < L; n++) {
+ g[n].re = 0.;
+ g[n].im = 0.;
+ }
+
+ for (int n = 0; n < N; n++) {
+ psi = n * theta + n * n / 2.0 * phi;
+ c = cos(psi);
+ S = -sin(psi);
+ a = c * g[n].re - S * g[n].im;
+ b = S * g[n].re + c * g[n].im;
+ g[n].re = a;
+ g[n].im = b;
+ }
+
+ av_fft_permute(s->fft[ch], h);
+ av_fft_calc(s->fft[ch], h);
+
+ av_fft_permute(s->fft[ch], g);
+ av_fft_calc(s->fft[ch], g);
+
+ for (int n = 0; n < L; n++) {
+ c = g[n].re;
+ S = g[n].im;
+ a = c * h[n].re - S * h[n].im;
+ b = S * h[n].re + c * h[n].im;
+
+ g[n].re = a / L;
+ g[n].im = b / L;
+ }
+
+ av_fft_permute(s->ifft[ch], g);
+ av_fft_calc(s->ifft[ch], g);
+
+ for (int k = 0; k < M; k++) {
+ psi = k * k / 2.0 * phi;
+ c = cos(psi);
+ S = -sin(psi);
+ a = c * g[k].re - S * g[k].im;
+ b = S * g[k].re + c * g[k].im;
+ s->fft_data[ch][k].re = a;
+ s->fft_data[ch][k].im = b;
+ }
+ } else {
+ /* run FFT on each samples set */
+ av_fft_permute(s->fft[ch], s->fft_data[ch]);
+ av_fft_calc(s->fft[ch], s->fft_data[ch]);
+ }
+
+ return 0;
+}
+
static int config_output(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
@@ -309,6 +425,12 @@ static int config_output(AVFilterLink *outlink)
int i, fft_bits, h, w;
float overlap;
+ s->stop = FFMIN(s->stop, inlink->sample_rate / 2);
+ if (s->stop && s->stop <= s->start) {
+ av_log(ctx, AV_LOG_ERROR, "Stop frequency should be greater than start.\n");
+ return AVERROR(EINVAL);
+ }
+
s->pts = AV_NOPTS_VALUE;
if (!strcmp(ctx->filter->name, "showspectrumpic"))
@@ -337,7 +459,9 @@ static int config_output(AVFilterLink *outlink)
/* FFT window size (precision) according to the requested output frame width */
for (fft_bits = 1; 1 << fft_bits < 2 * w; fft_bits++);
}
+
s->win_size = 1 << fft_bits;
+ s->buf_size = s->win_size << !!s->stop;
if (!s->fft) {
s->fft = av_calloc(inlink->channels, sizeof(*s->fft));
@@ -345,6 +469,14 @@ static int config_output(AVFilterLink *outlink)
return AVERROR(ENOMEM);
}
+ if (s->stop) {
+ if (!s->ifft) {
+ s->ifft = av_calloc(inlink->channels, sizeof(*s->ifft));
+ if (!s->ifft)
+ return AVERROR(ENOMEM);
+ }
+ }
+
/* (re-)configuration if the video output changed (or first init) */
if (fft_bits != s->fft_bits) {
AVFrame *outpicref;
@@ -355,6 +487,10 @@ static int config_output(AVFilterLink *outlink)
* Note: we use free and malloc instead of a realloc-like function to
* make sure the buffer is aligned in memory for the FFT functions. */
for (i = 0; i < s->nb_display_channels; i++) {
+ if (s->stop) {
+ av_fft_end(s->ifft[i]);
+ av_freep(&s->fft_scratch[i]);
+ }
av_fft_end(s->fft[i]);
av_freep(&s->fft_data[i]);
}
@@ -362,7 +498,15 @@ static int config_output(AVFilterLink *outlink)
s->nb_display_channels = inlink->channels;
for (i = 0; i < s->nb_display_channels; i++) {
- s->fft[i] = av_fft_init(fft_bits, 0);
+ s->fft[i] = av_fft_init(fft_bits + !!s->stop, 0);
+ if (s->stop) {
+ s->ifft[i] = av_fft_init(fft_bits + !!s->stop, 1);
+ if (!s->ifft[i]) {
+ av_log(ctx, AV_LOG_ERROR, "Unable to create Inverse FFT context. "
+ "The window size might be too high.\n");
+ return AVERROR(EINVAL);
+ }
+ }
if (!s->fft[i]) {
av_log(ctx, AV_LOG_ERROR, "Unable to create FFT context. "
"The window size might be too high.\n");
@@ -401,10 +545,17 @@ static int config_output(AVFilterLink *outlink)
s->fft_data = av_calloc(s->nb_display_channels, sizeof(*s->fft_data));
if (!s->fft_data)
return AVERROR(ENOMEM);
+ s->fft_scratch = av_calloc(s->nb_display_channels, sizeof(*s->fft_scratch));
+ if (!s->fft_scratch)
+ return AVERROR(ENOMEM);
for (i = 0; i < s->nb_display_channels; i++) {
- s->fft_data[i] = av_calloc(s->win_size, sizeof(**s->fft_data));
+ s->fft_data[i] = av_calloc(s->buf_size, sizeof(**s->fft_data));
if (!s->fft_data[i])
return AVERROR(ENOMEM);
+
+ s->fft_scratch[i] = av_calloc(s->buf_size, sizeof(**s->fft_scratch));
+ if (!s->fft_scratch[i])
+ return AVERROR(ENOMEM);
}
/* pre-calc windowing function */
@@ -472,29 +623,6 @@ static int config_output(AVFilterLink *outlink)
return 0;
}
-static int run_channel_fft(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
-{
- ShowSpectrumContext *s = ctx->priv;
- const float *window_func_lut = s->window_func_lut;
- AVFrame *fin = arg;
- const int ch = jobnr;
- int n;
-
- /* fill FFT input with the number of samples available */
- const float *p = (float *)fin->extended_data[ch];
-
- for (n = 0; n < s->win_size; n++) {
- s->fft_data[ch][n].re = p[n] * window_func_lut[n];
- s->fft_data[ch][n].im = 0;
- }
-
- /* run FFT on each samples set */
- av_fft_permute(s->fft[ch], s->fft_data[ch]);
- av_fft_calc(s->fft[ch], s->fft_data[ch]);
-
- return 0;
-}
-
#define RE(y, ch) s->fft_data[ch][y].re
#define IM(y, ch) s->fft_data[ch][y].im
#define MAGNITUDE(y, ch) hypot(RE(y, ch), IM(y, ch))
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