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avfilter/af_crossfeed: add option for linear phase filtering

But at expense of additional delay.

Paul B Mahol committed 4 years ago

Commit 5ccd8f41 parent 13098672 files · +167 −14Browse files

Unified · Split

2 files
  1. doc/filters.texi +7 −0
  2. libavfilter/af_crossfeed.c +160 −14
doc/filters.texi+7−0
@@ -4205,6 +4205,13 @@ Set input gain. Default is 0.9. · 4204 unmodified lines
42054205
42064206 @item level_out
42074207 Set output gain. Default is 1.
4208+
4209+@item block_size
4210+Set block size used for reverse IIR processing. If this value is set to high enough
4211+value (higher than impulse response length truncated when reaches near zero values) filtering
4212+will become linear phase otherwise if not big enough it will just produce nasty artifacts.
4213+
4214+Note that filter delay will be exactly this many samples when set to non-zero value.
42084215 @end table
42094216
42104217 @subsection Commands
libavfilter/af_crossfeed.c+160−14
@@ -21,6 +21,7 @@ · 20 unmodified lines
2121 #include "libavutil/opt.h"
2222 #include "avfilter.h"
2323 #include "audio.h"
24+#include "filters.h"
2425 #include "formats.h"
2526
2627 typedef struct CrossfeedContext {
@@ -31,11 +32,16 @@ typedef struct CrossfeedContext { · 4 unmodified lines
3132 double slope;
3233 double level_in;
3334 double level_out;
35+ int block_samples;
36+ int block_size;
3437
3538 double a0, a1, a2;
3639 double b0, b1, b2;
3740
3841 double w1, w2;
42+
43+ double *mid;
44+ double *side[3];
3945 } CrossfeedContext;
4046
4147 static int query_formats(AVFilterContext *ctx)
@@ -77,9 +83,49 @@ static int config_input(AVFilterLink *inlink) · 35 unmodified lines
7783 s->b1 /= s->a0;
7884 s->b2 /= s->a0;
7985
86+ if (s->block_samples == 0 && s->block_size > 0) {
87+ s->block_samples = s->block_size;
88+ s->mid = av_calloc(s->block_samples * 2, sizeof(*s->mid));
89+ for (int i = 0; i < 3; i++) {
90+ s->side[i] = av_calloc(s->block_samples * 2, sizeof(*s->side[0]));
91+ if (!s->side[i])
92+ return AVERROR(ENOMEM);
93+ }
94+ }
95+
8096 return 0;
8197 }
8298
99+static void reverse_samples(double *dst, const double *src,
100+ int nb_samples)
101+{
102+ for (int i = 0, j = nb_samples - 1; i < nb_samples; i++, j--)
103+ dst[i] = src[j];
104+}
105+
106+static void filter_samples(double *dst, const double *src,
107+ int nb_samples,
108+ double b0, double b1, double b2,
109+ double a1, double a2,
110+ double *sw1, double *sw2)
111+{
112+ double w1 = *sw1;
113+ double w2 = *sw2;
114+
115+ for (int n = 0; n < nb_samples; n++) {
116+ double side = src[n];
117+ double oside = side * b0 + w1;
118+
119+ w1 = b1 * side + w2 + a1 * oside;
120+ w2 = b2 * side + a2 * oside;
121+
122+ dst[n] = oside;
123+ }
124+
125+ *sw1 = w1;
126+ *sw2 = w2;
127+}
128+
83129 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
84130 {
85131 AVFilterContext *ctx = inlink->dst;
@@ -95,7 +141,6 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in) · 9 unmodified lines
95141 const double a2 = -s->a2;
96142 AVFrame *out;
97143 double *dst;
98− int n;
99144
100145 if (av_frame_is_writable(in)) {
101146 out = in;
@@ -109,21 +154,79 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in) · 7 unmodified lines
109154 }
110155 dst = (double *)out->data[0];
111156
112− for (n = 0; n < out->nb_samples; n++, src += 2, dst += 2) {
113− double mid = (src[0] + src[1]) * level_in * .5;
114− double side = (src[0] - src[1]) * level_in * .5;
115− double oside = side * b0 + s->w1;
157+ if (s->block_samples == 0) {
158+ double w1 = s->w1;
159+ double w2 = s->w2;
160+
161+ for (int n = 0; n < out->nb_samples; n++, src += 2, dst += 2) {
162+ double mid = (src[0] + src[1]) * level_in * .5;
163+ double side = (src[0] - src[1]) * level_in * .5;
164+ double oside = side * b0 + w1;
165+
166+ w1 = b1 * side + w2 + a1 * oside;
167+ w2 = b2 * side + a2 * oside;
168+
169+ if (ctx->is_disabled) {
170+ dst[0] = src[0];
171+ dst[1] = src[1];
172+ } else {
173+ dst[0] = (mid + oside) * level_out;
174+ dst[1] = (mid - oside) * level_out;
175+ }
176+ }
177+
178+ s->w1 = w1;
179+ s->w2 = w2;
180+ } else {
181+ double *mdst = s->mid + s->block_samples;
182+ double *sdst = s->side[0] + s->block_samples;
183+ double *ssrc = s->side[0];
184+ double *msrc = s->mid;
185+ double w1 = s->w1;
186+ double w2 = s->w2;
187+
188+ for (int n = 0; n < out->nb_samples; n++, src += 2) {
189+ mdst[n] = (src[0] + src[1]) * level_in * .5;
190+ sdst[n] = (src[0] - src[1]) * level_in * .5;
191+ }
192+
193+ sdst = s->side[1];
194+ filter_samples(sdst, ssrc, s->block_samples,
195+ b0, b1, b2, a1, a2,
196+ &w1, &w2);
197+ s->w1 = w1;
198+ s->w2 = w2;
116199
117− s->w1 = b1 * side + s->w2 + a1 * oside;
118− s->w2 = b2 * side + a2 * oside;
200+ ssrc = s->side[0] + s->block_samples;
201+ sdst = s->side[1] + s->block_samples;
202+ filter_samples(sdst, ssrc, s->block_samples,
203+ b0, b1, b2, a1, a2,
204+ &w1, &w2);
119205
120− if (ctx->is_disabled) {
121− dst[0] = src[0];
122− dst[1] = src[1];
123− } else {
124− dst[0] = (mid + oside) * level_out;
125− dst[1] = (mid - oside) * level_out;
206+ reverse_samples(s->side[2], s->side[1], s->block_samples * 2);
207+ w1 = w2 = 0.;
208+ filter_samples(s->side[2], s->side[2], s->block_samples * 2,
209+ b0, b1, b2, a1, a2,
210+ &w1, &w2);
211+
212+ reverse_samples(s->side[1], s->side[2] + s->block_samples, s->block_samples);
213+
214+ src = (const double *)in->data[0];
215+ ssrc = s->side[1];
216+ for (int n = 0; n < out->nb_samples; n++, src += 2, dst += 2) {
217+ if (ctx->is_disabled) {
218+ dst[0] = src[0];
219+ dst[1] = src[1];
220+ } else {
221+ dst[0] = (msrc[n] + ssrc[n]) * level_out;
222+ dst[1] = (msrc[n] - ssrc[n]) * level_out;
223+ }
126224 }
225+
226+ memmove(s->mid, s->mid + s->block_samples,
227+ s->block_samples * sizeof(*s->mid));
228+ memmove(s->side[0], s->side[0] + s->block_samples,
229+ s->block_samples * sizeof(*s->side[0]));
127230 }
128231
129232 if (out != in)
@@ -131,6 +234,37 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in) · 1 unmodified line
131234 return ff_filter_frame(outlink, out);
132235 }
133236
237+static int activate(AVFilterContext *ctx)
238+{
239+ AVFilterLink *inlink = ctx->inputs[0];
240+ AVFilterLink *outlink = ctx->outputs[0];
241+ CrossfeedContext *s = ctx->priv;
242+ AVFrame *in = NULL;
243+ int ret;
244+
245+ FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);
246+
247+ if (s->block_samples > 0) {
248+ ret = ff_inlink_consume_samples(inlink, s->block_samples, s->block_samples, &in);
249+ } else {
250+ ret = ff_inlink_consume_frame(inlink, &in);
251+ }
252+ if (ret < 0)
253+ return ret;
254+ if (ret > 0)
255+ return filter_frame(inlink, in);
256+
257+ if (s->block_samples > 0 && ff_inlink_queued_samples(inlink) >= s->block_samples) {
258+ ff_filter_set_ready(ctx, 10);
259+ return 0;
260+ }
261+
262+ FF_FILTER_FORWARD_STATUS(inlink, outlink);
263+ FF_FILTER_FORWARD_WANTED(outlink, inlink);
264+
265+ return FFERROR_NOT_READY;
266+}
267+
134268 static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
135269 char *res, int res_len, int flags)
136270 {
@@ -143,8 +277,18 @@ static int process_command(AVFilterContext *ctx, const char *cmd, const char *ar · 6 unmodified lines
143277 return config_input(ctx->inputs[0]);
144278 }
145279
280+static av_cold void uninit(AVFilterContext *ctx)
281+{
282+ CrossfeedContext *s = ctx->priv;
283+
284+ av_freep(&s->mid);
285+ for (int i = 0; i < 3; i++)
286+ av_freep(&s->side[i]);
287+}
288+
146289 #define OFFSET(x) offsetof(CrossfeedContext, x)
147290 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
291+#define AF AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
148292
149293 static const AVOption crossfeed_options[] = {
150294 { "strength", "set crossfeed strength", OFFSET(strength), AV_OPT_TYPE_DOUBLE, {.dbl=.2}, 0, 1, FLAGS },
@@ -152,6 +296,7 @@ static const AVOption crossfeed_options[] = { · 1 unmodified line
152296 { "slope", "set curve slope", OFFSET(slope), AV_OPT_TYPE_DOUBLE, {.dbl=.5}, .01, 1, FLAGS },
153297 { "level_in", "set level in", OFFSET(level_in), AV_OPT_TYPE_DOUBLE, {.dbl=.9}, 0, 1, FLAGS },
154298 { "level_out", "set level out", OFFSET(level_out), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0, 1, FLAGS },
299+ { "block_size", "set the block size", OFFSET(block_size),AV_OPT_TYPE_INT, {.i64=0}, 0, 32768, AF },
155300 { NULL }
156301 };
157302
@@ -161,7 +306,6 @@ static const AVFilterPad inputs[] = { · 3 unmodified lines
161306 {
162307 .name = "default",
163308 .type = AVMEDIA_TYPE_AUDIO,
164− .filter_frame = filter_frame,
165309 .config_props = config_input,
166310 },
167311 };
@@ -178,6 +322,8 @@ const AVFilter ff_af_crossfeed = { · 10 unmodified lines
178322 .description = NULL_IF_CONFIG_SMALL("Apply headphone crossfeed filter."),
179323 .priv_size = sizeof(CrossfeedContext),
180324 .priv_class = &crossfeed_class,
325+ .activate = activate,
326+ .uninit = uninit,
181327 FILTER_INPUTS(inputs),
182328 FILTER_OUTPUTS(outputs),
183329 FILTER_QUERY_FUNC(query_formats),

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