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avfilter/firequalizer: use zero phase kernel 

this makes real-valued kernel

Signed-off-by: Muhammad Faiz <mfcc64@gmail.com>
This commit is contained in:
Muhammad Faiz 2016-10-19 22:22:36 +07:00
parent 56689a46b3
commit 258c49d614
1 changed files with 15 additions and 11 deletions
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26
libavfilter/af_firequalizer.c
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@ -198,20 +198,19 @@ static void fast_convolute(FIREqualizerContext *s, const float *kernel_buf, floa
if (nsamples <= s->nsamples_max) { if (nsamples <= s->nsamples_max) {
float *buf = conv_buf + idx->buf_idx * s->rdft_len; float *buf = conv_buf + idx->buf_idx * s->rdft_len;
float *obuf = conv_buf + !idx->buf_idx * s->rdft_len + idx->overlap_idx; float *obuf = conv_buf + !idx->buf_idx * s->rdft_len + idx->overlap_idx;
int center = s->fir_len/2;
int k; int k;
memcpy(buf, data, nsamples * sizeof(*data)); memset(buf, 0, center * sizeof(*data));
memset(buf + nsamples, 0, (s->rdft_len - nsamples) * sizeof(*data)); memcpy(buf + center, data, nsamples * sizeof(*data));
memset(buf + center + nsamples, 0, (s->rdft_len - nsamples - center) * sizeof(*data));
av_rdft_calc(s->rdft, buf); av_rdft_calc(s->rdft, buf);
buf[0] *= kernel_buf[0]; buf[0] *= kernel_buf[0];
buf[1] *= kernel_buf[1]; buf[1] *= kernel_buf[s->rdft_len/2];
for (k = 2; k < s->rdft_len; k += 2) { for (k = 1; k < s->rdft_len/2; k++) {
float re, im; buf[2*k] *= kernel_buf[k];
re = buf[k] * kernel_buf[k] - buf[k+1] * kernel_buf[k+1]; buf[2*k+1] *= kernel_buf[k];
im = buf[k] * kernel_buf[k+1] + buf[k+1] * kernel_buf[k];
buf[k] = re;
buf[k+1] = im;
} }
av_rdft_calc(s->irdft, buf); av_rdft_calc(s->irdft, buf);
@ -534,8 +533,8 @@ static int generate_kernel(AVFilterContext *ctx, const char *gain, const char *g
} }
memset(s->analysis_buf + center + 1, 0, (s->analysis_rdft_len - s->fir_len) * sizeof(*s->analysis_buf)); memset(s->analysis_buf + center + 1, 0, (s->analysis_rdft_len - s->fir_len) * sizeof(*s->analysis_buf));
memcpy(rdft_buf, s->analysis_buf + s->analysis_rdft_len - center, center * sizeof(*s->analysis_buf)); memcpy(rdft_buf, s->analysis_buf, s->rdft_len/2 * sizeof(*s->analysis_buf));
memcpy(rdft_buf + center, s->analysis_buf, (s->rdft_len - center) * sizeof(*s->analysis_buf)); memcpy(rdft_buf + s->rdft_len/2, s->analysis_buf + s->analysis_rdft_len - s->rdft_len/2, s->rdft_len/2 * sizeof(*s->analysis_buf));
av_rdft_calc(s->rdft, rdft_buf); av_rdft_calc(s->rdft, rdft_buf);
for (k = 0; k < s->rdft_len; k++) { for (k = 0; k < s->rdft_len; k++) {
@ -548,6 +547,11 @@ static int generate_kernel(AVFilterContext *ctx, const char *gain, const char *g
} }
} }
rdft_buf[s->rdft_len-1] = rdft_buf[1];
for (k = 0; k < s->rdft_len/2; k++)
rdft_buf[k] = rdft_buf[2*k];
rdft_buf[s->rdft_len/2] = rdft_buf[s->rdft_len-1];
if (dump_fp) if (dump_fp)
dump_fir(ctx, dump_fp, ch); dump_fir(ctx, dump_fp, ch);