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- /*
- * Copyright (c) 2012 Nicolas George
- *
- * 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
- */
- #include "libavutil/channel_layout.h"
- #include "libavutil/avassert.h"
- #include "audio.h"
- #include "avfilter.h"
- #include "internal.h"
- typedef struct {
- /**
- * Number of samples at each PCM value.
- * histogram[0x8000 + i] is the number of samples at value i.
- * The extra element is there for symmetry.
- */
- uint64_t histogram[0x10001];
- } VolDetectContext;
- static int query_formats(AVFilterContext *ctx)
- {
- static const enum AVSampleFormat sample_fmts[] = {
- AV_SAMPLE_FMT_S16,
- AV_SAMPLE_FMT_S16P,
- AV_SAMPLE_FMT_NONE
- };
- AVFilterFormats *formats;
- if (!(formats = ff_make_format_list(sample_fmts)))
- return AVERROR(ENOMEM);
- return ff_set_common_formats(ctx, formats);
- }
- static int filter_frame(AVFilterLink *inlink, AVFrame *samples)
- {
- AVFilterContext *ctx = inlink->dst;
- VolDetectContext *vd = ctx->priv;
- int64_t layout = samples->channel_layout;
- int nb_samples = samples->nb_samples;
- int nb_channels = av_get_channel_layout_nb_channels(layout);
- int nb_planes = nb_channels;
- int plane, i;
- int16_t *pcm;
- if (!av_sample_fmt_is_planar(samples->format)) {
- nb_samples *= nb_channels;
- nb_planes = 1;
- }
- for (plane = 0; plane < nb_planes; plane++) {
- pcm = (int16_t *)samples->extended_data[plane];
- for (i = 0; i < nb_samples; i++)
- vd->histogram[pcm[i] + 0x8000]++;
- }
- return ff_filter_frame(inlink->dst->outputs[0], samples);
- }
- #define MAX_DB 91
- static inline double logdb(uint64_t v)
- {
- double d = v / (double)(0x8000 * 0x8000);
- if (!v)
- return MAX_DB;
- return -log10(d) * 10;
- }
- static void print_stats(AVFilterContext *ctx)
- {
- VolDetectContext *vd = ctx->priv;
- int i, max_volume, shift;
- uint64_t nb_samples = 0, power = 0, nb_samples_shift = 0, sum = 0;
- uint64_t histdb[MAX_DB + 1] = { 0 };
- for (i = 0; i < 0x10000; i++)
- nb_samples += vd->histogram[i];
- av_log(ctx, AV_LOG_INFO, "n_samples: %"PRId64"\n", nb_samples);
- if (!nb_samples)
- return;
- /* If nb_samples > 1<<34, there is a risk of overflow in the
- multiplication or the sum: shift all histogram values to avoid that.
- The total number of samples must be recomputed to avoid rounding
- errors. */
- shift = av_log2(nb_samples >> 33);
- for (i = 0; i < 0x10000; i++) {
- nb_samples_shift += vd->histogram[i] >> shift;
- power += (i - 0x8000) * (i - 0x8000) * (vd->histogram[i] >> shift);
- }
- if (!nb_samples_shift)
- return;
- power = (power + nb_samples_shift / 2) / nb_samples_shift;
- av_assert0(power <= 0x8000 * 0x8000);
- av_log(ctx, AV_LOG_INFO, "mean_volume: %.1f dB\n", -logdb(power));
- max_volume = 0x8000;
- while (max_volume > 0 && !vd->histogram[0x8000 + max_volume] &&
- !vd->histogram[0x8000 - max_volume])
- max_volume--;
- av_log(ctx, AV_LOG_INFO, "max_volume: %.1f dB\n", -logdb(max_volume * max_volume));
- for (i = 0; i < 0x10000; i++)
- histdb[(int)logdb((i - 0x8000) * (i - 0x8000))] += vd->histogram[i];
- for (i = 0; i <= MAX_DB && !histdb[i]; i++);
- for (; i <= MAX_DB && sum < nb_samples / 1000; i++) {
- av_log(ctx, AV_LOG_INFO, "histogram_%ddb: %"PRId64"\n", i, histdb[i]);
- sum += histdb[i];
- }
- }
- static av_cold void uninit(AVFilterContext *ctx)
- {
- print_stats(ctx);
- }
- static const AVFilterPad volumedetect_inputs[] = {
- {
- .name = "default",
- .type = AVMEDIA_TYPE_AUDIO,
- .filter_frame = filter_frame,
- },
- { NULL }
- };
- static const AVFilterPad volumedetect_outputs[] = {
- {
- .name = "default",
- .type = AVMEDIA_TYPE_AUDIO,
- },
- { NULL }
- };
- AVFilter ff_af_volumedetect = {
- .name = "volumedetect",
- .description = NULL_IF_CONFIG_SMALL("Detect audio volume."),
- .priv_size = sizeof(VolDetectContext),
- .query_formats = query_formats,
- .uninit = uninit,
- .inputs = volumedetect_inputs,
- .outputs = volumedetect_outputs,
- };
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