[FFmpeg-devel] [PATCH] avfilter: add arbitrary audio FIR filter

Paul B Mahol onemda at gmail.com
Fri May 5 22:30:38 EEST 2017


Signed-off-by: Paul B Mahol <onemda at gmail.com>
---
 configure                |   2 +
 doc/filters.texi         |  10 +
 libavfilter/Makefile     |   1 +
 libavfilter/af_afir.c    | 484 +++++++++++++++++++++++++++++++++++++++++++++++
 libavfilter/allfilters.c |   1 +
 5 files changed, 498 insertions(+)
 create mode 100644 libavfilter/af_afir.c

diff --git a/configure b/configure
index b3cb5b0..0d83c6a 100755
--- a/configure
+++ b/configure
@@ -3078,6 +3078,8 @@ unix_protocol_select="network"
 # filters
 afftfilt_filter_deps="avcodec"
 afftfilt_filter_select="fft"
+afir_filter_deps="avcodec"
+afir_filter_select="fft"
 amovie_filter_deps="avcodec avformat"
 aresample_filter_deps="swresample"
 ass_filter_deps="libass"
diff --git a/doc/filters.texi b/doc/filters.texi
index 119e747..ea343d1 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -878,6 +878,16 @@ afftfilt="1-clip((b/nb)*b,0,1)"
 @end example
 @end itemize
 
+ at section afirfilter
+
+Apply an Arbitary Frequency Impulse Response filter.
+
+This filter uses second stream as FIR coefficients.
+If second stream holds single channel, it will be used
+for all input channels in first stream, otherwise
+number of channels in second stream must be same as
+number of channels in first stream.
+
 @anchor{aformat}
 @section aformat
 
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 66c36e4..c797eb5 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -38,6 +38,7 @@ OBJS-$(CONFIG_AEMPHASIS_FILTER)              += af_aemphasis.o
 OBJS-$(CONFIG_AEVAL_FILTER)                  += aeval.o
 OBJS-$(CONFIG_AFADE_FILTER)                  += af_afade.o
 OBJS-$(CONFIG_AFFTFILT_FILTER)               += af_afftfilt.o window_func.o
+OBJS-$(CONFIG_AFIR_FILTER)                   += af_afir.o
 OBJS-$(CONFIG_AFORMAT_FILTER)                += af_aformat.o
 OBJS-$(CONFIG_AGATE_FILTER)                  += af_agate.o
 OBJS-$(CONFIG_AINTERLEAVE_FILTER)            += f_interleave.o
diff --git a/libavfilter/af_afir.c b/libavfilter/af_afir.c
new file mode 100644
index 0000000..9411c9b
--- /dev/null
+++ b/libavfilter/af_afir.c
@@ -0,0 +1,484 @@
+/*
+ * Copyright (c) 2017 Paul B Mahol
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * An arbitrary audio FIR filter
+ */
+
+#include "libavutil/audio_fifo.h"
+#include "libavutil/common.h"
+#include "libavutil/opt.h"
+#include "libavcodec/avfft.h"
+
+#include "audio.h"
+#include "avfilter.h"
+#include "formats.h"
+#include "internal.h"
+
+#define MAX_IR_DURATION 20
+
+typedef struct FIRContext {
+    const AVClass *class;
+
+    float wet_gain;
+    float dry_gain;
+    int auto_gain;
+
+    float gain;
+
+    int eof_coeffs;
+    int have_coeffs;
+    int nb_coeffs;
+    int nb_taps;
+    int part_size;
+    int nb_partitions;
+    int fft_length;
+    int nb_channels;
+    int nb_coef_channels;
+    int one2many;
+    int nb_samples;
+
+    RDFTContext **rdft, **irdft;
+    float **sum;
+    float **block;
+    FFTComplex **coeff;
+
+    AVAudioFifo *fifo[2];
+    AVFrame *in[2];
+    AVFrame *buffer;
+    int64_t pts;
+} FIRContext;
+
+static int fir_channel(AVFilterContext *ctx, void *arg, int ch, int nb_jobs)
+{
+    FIRContext *s = ctx->priv;
+    AVFrame *out = arg;
+    const FFTComplex *coeff = s->coeff[ch * !s->one2many];
+    const float *src = (const float *)s->in[0]->extended_data[ch];
+    float *dst = (float *)out->extended_data[ch];
+    float *buf = (float *)s->buffer->extended_data[ch];
+    float *sum = s->sum[ch];
+    float *block = s->block[ch];
+    int n, i;
+
+    memset(sum, 0, sizeof(*sum) * 2 * (s->part_size + 1));
+    memset(block, 0, sizeof(*block) * 2 * (s->part_size + 1));
+    for (n = 0; n < s->nb_samples; n++) {
+        block[n] = src[n] * s->dry_gain;
+    }
+
+    av_rdft_calc(s->rdft[ch], block);
+    block[s->part_size / 2] = block[1];
+    block[1] = 0;
+
+    for (i = 0; i < s->nb_partitions; i++) {
+        const int coffset = i * (s->part_size + 1);
+
+        for (n = 0; n <= s->part_size; n++) {
+            const float re = block[2 * n    ];
+            const float im = block[2 * n + 1];
+            const float cre = coeff[coffset + n].re;
+            const float cim = coeff[coffset + n].im;
+
+            sum[2 * n    ] += re * cre - im * cim;
+            sum[2 * n + 1] += re * cim + im * cre;
+        }
+    }
+
+    sum[1] = sum[n];
+    av_rdft_calc(s->irdft[ch], sum);
+
+    for (n = 0; n < out->nb_samples; n++) {
+        float sample;
+
+        sample = sum[out->nb_samples + n];
+        dst[n] = sample * s->wet_gain * s->gain;
+        buf[n] = sum[n];
+    }
+
+    return 0;
+}
+
+static int fir_frame(FIRContext *s, AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    AVFrame *out;
+
+    s->nb_samples = FFMIN(s->part_size, av_audio_fifo_size(s->fifo[0]));
+
+    out = ff_get_audio_buffer(outlink, s->nb_samples < s->part_size / 2 ? s->nb_samples : s->part_size / 2);
+    if (!out)
+        return AVERROR(ENOMEM);
+    s->in[0] = ff_get_audio_buffer(ctx->inputs[0], s->nb_samples);
+    if (!s->in[0]) {
+        av_frame_free(&out);
+        return AVERROR(ENOMEM);
+    }
+
+    av_audio_fifo_peek(s->fifo[0], (void **)s->in[0]->extended_data, s->nb_samples);
+
+    ctx->internal->execute(ctx, fir_channel, out, NULL, outlink->channels);
+
+    av_audio_fifo_drain(s->fifo[0], out->nb_samples);
+
+    out->pts = s->pts;
+    if (s->pts != AV_NOPTS_VALUE)
+        s->pts += av_rescale_q(out->nb_samples, (AVRational){1, outlink->sample_rate}, outlink->time_base);
+
+    av_frame_free(&s->in[0]);
+
+    return ff_filter_frame(outlink, out);
+}
+
+static int convert_coeffs(AVFilterContext *ctx)
+{
+    FIRContext *s = ctx->priv;
+    int max_nb_taps, i, ch, n, N;
+    float power = 0;
+
+    s->nb_taps = av_audio_fifo_size(s->fifo[1]);
+    max_nb_taps = MAX_IR_DURATION * ctx->outputs[0]->sample_rate;
+    if (s->nb_taps > max_nb_taps) {
+        av_log(ctx, AV_LOG_ERROR, "Too big number of coefficients: %d > %d.\n", s->nb_taps, max_nb_taps);
+        return AVERROR(EINVAL);
+    }
+
+    for (n = 1; (1 << n) < s->nb_taps; n++);
+    N = FFMIN(n, 16);
+    s->fft_length = 1 << n;
+    s->part_size = 1 << (N - 1);
+    s->nb_partitions = (s->fft_length + s->part_size - 1) / s->part_size;
+    s->nb_coeffs = s->fft_length + s->nb_partitions;
+
+    for (ch = 0; ch < ctx->inputs[0]->channels; ch++) {
+        s->sum[ch] = av_calloc(2 * (s->part_size + 1), sizeof(**s->sum));
+        if (!s->sum[ch])
+            return AVERROR(ENOMEM);
+    }
+
+    for (ch = 0; ch < ctx->inputs[1]->channels; ch++) {
+        s->coeff[ch] = av_calloc(s->nb_coeffs, sizeof(**s->coeff));
+        if (!s->coeff[ch])
+            return AVERROR(ENOMEM);
+    }
+
+    for (ch = 0; ch < ctx->inputs[0]->channels; ch++) {
+        s->block[ch] = av_calloc(2 * (s->part_size + 1), sizeof(**s->block));
+        if (!s->block[ch])
+            return AVERROR(ENOMEM);
+    }
+
+    s->buffer = ff_get_audio_buffer(ctx->inputs[0], s->part_size);
+    if (!s->buffer)
+        return AVERROR(ENOMEM);
+
+    for (ch = 0; ch < ctx->inputs[0]->channels; ch++) {
+        s->rdft[ch]  = av_rdft_init(N, DFT_R2C);
+        s->irdft[ch] = av_rdft_init(N, IDFT_C2R);
+        if (!s->rdft[ch] || !s->irdft[ch])
+            return AVERROR(ENOMEM);
+    }
+
+    s->in[1] = ff_get_audio_buffer(ctx->inputs[1], s->nb_taps);
+    if (!s->in[1])
+        return AVERROR(ENOMEM);
+
+    av_audio_fifo_read(s->fifo[1], (void **)s->in[1]->extended_data, s->nb_taps);
+    for (ch = 0; ch < ctx->inputs[1]->channels; ch++) {
+        const float *re = (const float *)s->in[1]->extended_data[!s->one2many * ch];
+        float *block = s->block[ch];
+        FFTComplex *coeff = s->coeff[ch];
+
+        for (i = 0; i < s->nb_partitions; i++) {
+            const int offset = i * s->part_size;
+            const int coffset = i * (s->part_size + 1);
+            const int remaining = s->nb_taps - (i * s->part_size);
+            const int size = remaining >= s->part_size ? s->part_size : remaining;
+
+            memset(block, 0, sizeof(*block) * (2 * (s->part_size + 1)));
+            for (n = 0; n < size; n++) {
+                block[n] = re[n + offset];
+                power += block[n] * block[n];
+            }
+
+            av_rdft_calc(s->rdft[0], block);
+
+            coeff[coffset].re = block[0];
+            coeff[coffset].im = 0;
+            for (n = 1; n < s->part_size; n++) {
+                coeff[coffset + n].re = block[2 * n];
+                coeff[coffset + n].im = block[2 * n + 1];
+            }
+            coeff[coffset + n].re = block[1];
+            coeff[coffset + n].im = 0;
+        }
+    }
+    power /= ctx->inputs[1]->channels;
+
+    av_frame_free(&s->in[1]);
+    s->gain = (1.f / (1 << N)) / (s->auto_gain ? sqrtf(power) : sqrtf(s->part_size));
+    av_log(ctx, AV_LOG_DEBUG, "partition size: %d\n", 1 << N);
+    av_log(ctx, AV_LOG_DEBUG, "nb_taps: %d\n", s->nb_taps);
+    av_log(ctx, AV_LOG_DEBUG, "fft_length: %d\n", s->fft_length);
+    av_log(ctx, AV_LOG_DEBUG, "nb_partitions: %d\n", s->nb_partitions);
+
+    s->have_coeffs = 1;
+
+    return 0;
+}
+
+static int read_ir(AVFilterLink *link, AVFrame *frame)
+{
+    AVFilterContext *ctx = link->dst;
+    FIRContext *s = ctx->priv;
+    int nb_taps, max_nb_taps;
+
+    av_audio_fifo_write(s->fifo[1], (void **)frame->extended_data,
+                        frame->nb_samples);
+    av_frame_free(&frame);
+
+    nb_taps = av_audio_fifo_size(s->fifo[1]);
+    max_nb_taps = MAX_IR_DURATION * ctx->outputs[0]->sample_rate;
+    if (s->nb_taps > max_nb_taps) {
+        av_log(ctx, AV_LOG_ERROR, "Too big number of coefficients: %d > %d.\n", nb_taps, max_nb_taps);
+        return AVERROR(EINVAL);
+    }
+
+    return 0;
+}
+
+static int filter_frame(AVFilterLink *link, AVFrame *frame)
+{
+    AVFilterContext *ctx = link->dst;
+    FIRContext *s = ctx->priv;
+    AVFilterLink *outlink = ctx->outputs[0];
+    int ret = 0;
+
+    av_audio_fifo_write(s->fifo[0], (void **)frame->extended_data,
+                        frame->nb_samples);
+    if (s->pts == AV_NOPTS_VALUE)
+        s->pts = frame->pts;
+
+    av_frame_free(&frame);
+
+    if (!s->have_coeffs && s->eof_coeffs) {
+        ret = convert_coeffs(ctx);
+        if (ret < 0)
+            return ret;
+    }
+
+    if (s->have_coeffs) {
+        while (av_audio_fifo_size(s->fifo[0]) >= s->part_size) {
+            ret = fir_frame(s, outlink);
+            if (ret < 0)
+                break;
+        }
+    }
+    return ret;
+}
+
+static int request_frame(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    FIRContext *s = ctx->priv;
+    int ret;
+
+    if (!s->eof_coeffs) {
+        ret = ff_request_frame(ctx->inputs[1]);
+        if (ret == AVERROR_EOF) {
+            s->eof_coeffs = 1;
+            ret = 0;
+        }
+        return ret;
+    }
+    ret = ff_request_frame(ctx->inputs[0]);
+    if (ret == AVERROR_EOF && s->have_coeffs) {
+        while (av_audio_fifo_size(s->fifo[0]) > 0) {
+            ret = fir_frame(s, outlink);
+            if (ret < 0)
+                return ret;
+        }
+        ret = AVERROR_EOF;
+    }
+    return ret;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    AVFilterFormats *formats;
+    AVFilterChannelLayouts *layouts = NULL;
+    static const enum AVSampleFormat sample_fmts[] = {
+        AV_SAMPLE_FMT_FLTP,
+        AV_SAMPLE_FMT_NONE
+    };
+    int ret, i;
+
+    layouts = ff_all_channel_counts();
+    if ((ret = ff_channel_layouts_ref(layouts, &ctx->outputs[0]->in_channel_layouts)) < 0)
+        return ret;
+
+    for (i = 0; i < 2; i++) {
+        layouts = ff_all_channel_counts();
+        if ((ret = ff_channel_layouts_ref(layouts, &ctx->inputs[i]->out_channel_layouts)) < 0)
+            return ret;
+    }
+
+    formats = ff_make_format_list(sample_fmts);
+    if ((ret = ff_set_common_formats(ctx, formats)) < 0)
+        return ret;
+
+    formats = ff_all_samplerates();
+    return ff_set_common_samplerates(ctx, formats);
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    FIRContext *s = ctx->priv;
+
+    if (ctx->inputs[0]->channels != ctx->inputs[1]->channels &&
+        ctx->inputs[1]->channels != 1) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Second input must have same number of channels as first input or "
+               "exactly 1 channel.\n");
+        return AVERROR(EINVAL);
+    }
+
+    s->one2many = ctx->inputs[1]->channels == 1;
+    outlink->sample_rate = ctx->inputs[0]->sample_rate;
+    outlink->time_base   = ctx->inputs[0]->time_base;
+    outlink->channel_layout = ctx->inputs[0]->channel_layout;
+    outlink->channels = ctx->inputs[0]->channels;
+
+    s->fifo[0] = av_audio_fifo_alloc(ctx->inputs[0]->format, ctx->inputs[0]->channels, 1024);
+    s->fifo[1] = av_audio_fifo_alloc(ctx->inputs[1]->format, ctx->inputs[1]->channels, 1024);
+    if (!s->fifo[0] || !s->fifo[1])
+        return AVERROR(ENOMEM);
+
+    s->sum = av_calloc(outlink->channels, sizeof(*s->sum));
+    s->coeff = av_calloc(ctx->inputs[1]->channels, sizeof(*s->coeff));
+    s->block = av_calloc(ctx->inputs[0]->channels, sizeof(*s->block));
+    s->rdft = av_calloc(outlink->channels, sizeof(*s->rdft));
+    s->irdft = av_calloc(outlink->channels, sizeof(*s->irdft));
+    if (!s->sum || !s->coeff || !s->block || !s->rdft || !s->irdft)
+        return AVERROR(ENOMEM);
+
+    s->nb_channels = outlink->channels;
+    s->nb_coef_channels = ctx->inputs[1]->channels;
+    s->pts = AV_NOPTS_VALUE;
+
+    return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    FIRContext *s = ctx->priv;
+    int ch;
+
+    if (s->sum) {
+        for (ch = 0; ch < s->nb_channels; ch++) {
+            av_freep(&s->sum[ch]);
+        }
+    }
+    av_freep(&s->sum);
+
+    if (s->coeff) {
+        for (ch = 0; ch < s->nb_coef_channels; ch++) {
+            av_freep(&s->coeff[ch]);
+        }
+    }
+    av_freep(&s->coeff);
+
+    if (s->block) {
+        for (ch = 0; ch < s->nb_channels; ch++) {
+            av_freep(&s->block[ch]);
+        }
+    }
+    av_freep(&s->block);
+
+    if (s->rdft) {
+        for (ch = 0; ch < s->nb_channels; ch++) {
+            av_rdft_end(s->rdft[ch]);
+        }
+    }
+    av_freep(&s->rdft);
+
+    if (s->irdft) {
+        for (ch = 0; ch < s->nb_channels; ch++) {
+            av_rdft_end(s->irdft[ch]);
+        }
+    }
+    av_freep(&s->irdft);
+
+    av_frame_free(&s->in[0]);
+    av_frame_free(&s->in[1]);
+    av_frame_free(&s->buffer);
+
+    av_audio_fifo_free(s->fifo[0]);
+    av_audio_fifo_free(s->fifo[1]);
+}
+
+static const AVFilterPad afir_inputs[] = {
+    {
+        .name           = "main",
+        .type           = AVMEDIA_TYPE_AUDIO,
+        .filter_frame   = filter_frame,
+    },{
+        .name           = "ir",
+        .type           = AVMEDIA_TYPE_AUDIO,
+        .filter_frame   = read_ir,
+    },
+    { NULL }
+};
+
+static const AVFilterPad afir_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_AUDIO,
+        .config_props  = config_output,
+        .request_frame = request_frame,
+    },
+    { NULL }
+};
+
+#define AF AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+#define OFFSET(x) offsetof(FIRContext, x)
+
+static const AVOption afir_options[] = {
+    { "dry",  "set dry gain",     OFFSET(dry_gain),  AV_OPT_TYPE_FLOAT, {.dbl=1}, 0, 1, AF },
+    { "wet",  "set wet gain",     OFFSET(wet_gain),  AV_OPT_TYPE_FLOAT, {.dbl=1}, 0, 1, AF },
+    { "auto", "enable auto-gain", OFFSET(auto_gain), AV_OPT_TYPE_BOOL,  {.i64=1}, 0, 1, AF },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(afir);
+
+AVFilter ff_af_afir = {
+    .name          = "afir",
+    .description   = NULL_IF_CONFIG_SMALL("Apply Finite Impulse Response filter with supplied coefficients in 2nd stream."),
+    .priv_size     = sizeof(FIRContext),
+    .priv_class    = &afir_class,
+    .query_formats = query_formats,
+    .uninit        = uninit,
+    .inputs        = afir_inputs,
+    .outputs       = afir_outputs,
+    .flags         = AVFILTER_FLAG_SLICE_THREADS,
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 8fb87eb..555c442 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -50,6 +50,7 @@ static void register_all(void)
     REGISTER_FILTER(AEVAL,          aeval,          af);
     REGISTER_FILTER(AFADE,          afade,          af);
     REGISTER_FILTER(AFFTFILT,       afftfilt,       af);
+    REGISTER_FILTER(AFIR,           afir,           af);
     REGISTER_FILTER(AFORMAT,        aformat,        af);
     REGISTER_FILTER(AGATE,          agate,          af);
     REGISTER_FILTER(AINTERLEAVE,    ainterleave,    af);
-- 
2.9.3



More information about the ffmpeg-devel mailing list