[FFmpeg-cvslog] avfilter/avf_showspectrum: switch to FFT
Paul B Mahol
git at videolan.org
Sun Jan 3 23:12:21 CET 2016
ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Sun Jan 3 22:03:10 2016 +0100| [14caf9667e3f588d6497b68f3c0ab3b6592d328b] | committer: Paul B Mahol
avfilter/avf_showspectrum: switch to FFT
Rationale: supports >16 bit audio, more than 96dB SNR.
Signed-off-by: Paul B Mahol <onemda at gmail.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=14caf9667e3f588d6497b68f3c0ab3b6592d328b
---
libavfilter/avf_showspectrum.c | 90 +++++++++++++++++++++-------------------
1 file changed, 47 insertions(+), 43 deletions(-)
diff --git a/libavfilter/avf_showspectrum.c b/libavfilter/avf_showspectrum.c
index d9fae7f..6e73b9e 100644
--- a/libavfilter/avf_showspectrum.c
+++ b/libavfilter/avf_showspectrum.c
@@ -59,9 +59,9 @@ typedef struct {
int scale;
float saturation; ///< color saturation multiplier
int xpos; ///< x position (current column)
- RDFTContext *rdft; ///< Real Discrete Fourier Transform context
- int rdft_bits; ///< number of bits (RDFT window size = 1<<rdft_bits)
- FFTSample **rdft_data; ///< bins holder for each (displayed) channels
+ FFTContext *fft; ///< 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
float *window_func_lut; ///< Window function LUT
float **magnitudes;
int win_func;
@@ -195,12 +195,12 @@ static av_cold void uninit(AVFilterContext *ctx)
int i;
av_freep(&s->combine_buffer);
- av_rdft_end(s->rdft);
- if (s->rdft_data) {
+ av_fft_end(s->fft);
+ if (s->fft_data) {
for (i = 0; i < s->nb_display_channels; i++)
- av_freep(&s->rdft_data[i]);
+ av_freep(&s->fft_data[i]);
}
- av_freep(&s->rdft_data);
+ av_freep(&s->fft_data);
av_freep(&s->window_func_lut);
if (s->magnitudes) {
for (i = 0; i < s->nb_display_channels; i++)
@@ -217,7 +217,7 @@ static int query_formats(AVFilterContext *ctx)
AVFilterChannelLayouts *layouts = NULL;
AVFilterLink *inlink = ctx->inputs[0];
AVFilterLink *outlink = ctx->outputs[0];
- static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16P, AV_SAMPLE_FMT_NONE };
+ static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_NONE };
static const enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_NONE };
int ret;
@@ -247,7 +247,7 @@ static int config_output(AVFilterLink *outlink)
AVFilterContext *ctx = outlink->src;
AVFilterLink *inlink = ctx->inputs[0];
ShowSpectrumContext *s = ctx->priv;
- int i, rdft_bits, h, w;
+ int i, fft_bits, h, w;
float overlap;
if (!strcmp(ctx->filter->name, "showspectrumpic"))
@@ -262,33 +262,33 @@ static int config_output(AVFilterLink *outlink)
s->channel_width = w;
if (s->orientation == VERTICAL) {
- /* RDFT window size (precision) according to the requested output frame height */
- for (rdft_bits = 1; 1 << rdft_bits < 2 * h; rdft_bits++);
+ /* FFT window size (precision) according to the requested output frame height */
+ for (fft_bits = 1; 1 << fft_bits < 2 * h; fft_bits++);
} else {
- /* RDFT window size (precision) according to the requested output frame width */
- for (rdft_bits = 1; 1 << rdft_bits < 2 * w; rdft_bits++);
+ /* 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 << rdft_bits;
+ s->win_size = 1 << fft_bits;
/* (re-)configuration if the video output changed (or first init) */
- if (rdft_bits != s->rdft_bits) {
+ if (fft_bits != s->fft_bits) {
AVFrame *outpicref;
- av_rdft_end(s->rdft);
- s->rdft = av_rdft_init(rdft_bits, DFT_R2C);
- if (!s->rdft) {
- av_log(ctx, AV_LOG_ERROR, "Unable to create RDFT context. "
+ av_fft_end(s->fft);
+ s->fft = av_fft_init(fft_bits, 0);
+ if (!s->fft) {
+ av_log(ctx, AV_LOG_ERROR, "Unable to create FFT context. "
"The window size might be too high.\n");
return AVERROR(EINVAL);
}
- s->rdft_bits = rdft_bits;
+ s->fft_bits = fft_bits;
- /* RDFT buffers: x2 for each (display) channel buffer.
+ /* FFT buffers: x2 for each (display) channel buffer.
* 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++)
- av_freep(&s->rdft_data[i]);
- av_freep(&s->rdft_data);
+ av_freep(&s->fft_data[i]);
+ av_freep(&s->fft_data);
s->nb_display_channels = inlink->channels;
s->magnitudes = av_calloc(s->nb_display_channels, sizeof(*s->magnitudes));
@@ -300,12 +300,12 @@ static int config_output(AVFilterLink *outlink)
return AVERROR(ENOMEM);
}
- s->rdft_data = av_calloc(s->nb_display_channels, sizeof(*s->rdft_data));
- if (!s->rdft_data)
+ s->fft_data = av_calloc(s->nb_display_channels, sizeof(*s->fft_data));
+ if (!s->fft_data)
return AVERROR(ENOMEM);
for (i = 0; i < s->nb_display_channels; i++) {
- s->rdft_data[i] = av_calloc(s->win_size, sizeof(**s->rdft_data));
- if (!s->rdft_data[i])
+ s->fft_data[i] = av_calloc(s->win_size, sizeof(**s->fft_data));
+ if (!s->fft_data[i])
return AVERROR(ENOMEM);
}
@@ -327,7 +327,7 @@ static int config_output(AVFilterLink *outlink)
for (s->win_scale = 0, i = 0; i < s->win_size; i++) {
s->win_scale += s->window_func_lut[i] * s->window_func_lut[i];
}
- s->win_scale = 1. / (sqrt(s->win_scale) * 32768.);
+ s->win_scale = 1. / sqrt(s->win_scale);
/* prepare the initial picref buffer (black frame) */
av_frame_free(&s->outpicref);
@@ -363,7 +363,7 @@ static int config_output(AVFilterLink *outlink)
sizeof(*s->combine_buffer));
}
- av_log(ctx, AV_LOG_VERBOSE, "s:%dx%d RDFT window size:%d\n",
+ av_log(ctx, AV_LOG_VERBOSE, "s:%dx%d FFT window size:%d\n",
s->w, s->h, s->win_size);
av_audio_fifo_free(s->fifo);
@@ -373,25 +373,29 @@ static int config_output(AVFilterLink *outlink)
return 0;
}
-static void run_rdft(ShowSpectrumContext *s, AVFrame *fin)
+static void run_fft(ShowSpectrumContext *s, AVFrame *fin)
{
int ch, n;
- /* fill RDFT input with the number of samples available */
+ /* fill FFT input with the number of samples available */
for (ch = 0; ch < s->nb_display_channels; ch++) {
- const int16_t *p = (int16_t *)fin->extended_data[ch];
+ const float *p = (float *)fin->extended_data[ch];
- for (n = 0; n < s->win_size; n++)
- s->rdft_data[ch][n] = p[n] * s->window_func_lut[n];
+ for (n = 0; n < s->win_size; n++) {
+ s->fft_data[ch][n].re = p[n] * s->window_func_lut[n];
+ s->fft_data[ch][n].im = 0;
+ }
}
- /* run RDFT on each samples set */
- for (ch = 0; ch < s->nb_display_channels; ch++)
- av_rdft_calc(s->rdft, s->rdft_data[ch]);
+ /* run FFT on each samples set */
+ for (ch = 0; ch < s->nb_display_channels; ch++) {
+ av_fft_permute(s->fft, s->fft_data[ch]);
+ av_fft_calc(s->fft, s->fft_data[ch]);
+ }
}
-#define RE(y, ch) s->rdft_data[ch][2 * (y) + 0]
-#define IM(y, ch) s->rdft_data[ch][2 * (y) + 1]
+#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))
static void calc_magnitudes(ShowSpectrumContext *s)
@@ -721,7 +725,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
av_assert0(fin->nb_samples == s->win_size);
- run_rdft(s, fin);
+ run_fft(s, fin);
calc_magnitudes(s);
ret = plot_spectrum_column(inlink, fin);
@@ -847,12 +851,12 @@ static int showspectrumpic_request_frame(AVFilterLink *outlink)
if (ret < s->win_size) {
for (ch = 0; ch < s->nb_display_channels; ch++) {
- memset(fin->extended_data[ch] + ret * sizeof(int16_t), 0,
- (s->win_size - ret) * sizeof(int16_t));
+ memset(fin->extended_data[ch] + ret * sizeof(float), 0,
+ (s->win_size - ret) * sizeof(float));
}
}
- run_rdft(s, fin);
+ run_fft(s, fin);
acalc_magnitudes(s);
consumed += spf;
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