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avfilter/avf_showspectrum: switch to FFT

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Rationale: supports >16 bit audio, more than 96dB SNR.

Signed-off-by: Paul B Mahol <onemda@gmail.com>
pull/172/head
Paul B Mahol 9 years ago
parent ae9f2e6f28
commit 14caf9667e
1 changed files with 47 additions and 43 deletions
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  1. 90
      libavfilter/avf_showspectrum.c

90
libavfilter/avf_showspectrum.c
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@ -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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