[FFmpeg-devel] [PATCH v2 1/3] avfilter/volume: add volume scaling utilities.
cenzhanquan2 at gmail.com
cenzhanquan2 at gmail.com
Mon Jul 21 15:04:42 EEST 2025
From: zhanquan cen <cenzhanquan2 at gmail.com>
---
volume.c | 168 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
volume.h | 44 +++++++++++++++
2 files changed, 212 insertions(+)
create mode 100644 volume.c
create mode 100644 volume.h
diff --git a/volume.c b/volume.c
new file mode 100644
index 0000000000..373895924c
--- /dev/null
+++ b/volume.c
@@ -0,0 +1,168 @@
+
+/*
+ * 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
+ * audio volume for src filter
+ */
+#include "libavutil/mem.h"
+#include "volume.h"
+static inline void fade_samples_s16_small(int16_t *dst, const int16_t *src,
+ int nb_samples, int chs, int16_t dst_volume, int16_t src_volume)
+{
+ int i, j, k = 0;
+ int32_t step;
+ step = ((dst_volume - src_volume) << 15) / nb_samples;
+ for (i = 0; i < nb_samples; i++) {
+ for (j = 0; j < chs; j++, k++) {
+ dst[k] = av_clip_int16((src[k] * (src_volume + (step * i >> 15)) + 0x4000) >> 15);
+ }
+ }
+}
+static inline void scale_samples_u8(uint8_t *dst, const uint8_t *src,
+ int nb_samples, int volume)
+{
+ int i;
+ for (i = 0; i < nb_samples; i++)
+ dst[i] = av_clip_uint8(((((int64_t)src[i] - 128) * volume + 128) >> 8) + 128);
+}
+static inline void scale_samples_u8_small(uint8_t *dst, const uint8_t *src,
+ int nb_samples, int volume)
+{
+ int i;
+ for (i = 0; i < nb_samples; i++)
+ dst[i] = av_clip_uint8((((src[i] - 128) * volume + 128) >> 8) + 128);
+}
+static inline void scale_samples_s16(uint8_t *dst, const uint8_t *src,
+ int nb_samples, int volume)
+{
+ int i;
+ int16_t *smp_dst = (int16_t *)dst;
+ const int16_t *smp_src = (const int16_t *)src;
+ for (i = 0; i < nb_samples; i++)
+ smp_dst[i] = av_clip_int16(((int64_t)smp_src[i] * volume + 128) >> 8);
+}
+static inline void scale_samples_s16_small(uint8_t *dst, const uint8_t *src,
+ int nb_samples, int volume)
+{
+ int i;
+ int16_t *smp_dst = (int16_t *)dst;
+ const int16_t *smp_src = (const int16_t *)src;
+ for (i = 0; i < nb_samples; i++)
+ smp_dst[i] = av_clip_int16((smp_src[i] * volume + 128) >> 8);
+}
+static inline void scale_samples_s32(uint8_t *dst, const uint8_t *src,
+ int nb_samples, int volume)
+{
+ int i;
+ int32_t *smp_dst = (int32_t *)dst;
+ const int32_t *smp_src = (const int32_t *)src;
+ for (i = 0; i < nb_samples; i++)
+ smp_dst[i] = av_clipl_int32((((int64_t)smp_src[i] * volume + 128) >> 8));
+}
+static av_cold void scaler_init(VolumeContext *vol)
+{
+ int32_t volume_i = (int32_t)(vol->volume * 256 + 0.5);
+ vol->samples_align = 1;
+ switch (av_get_packed_sample_fmt(vol->sample_fmt)) {
+ case AV_SAMPLE_FMT_U8:
+ if (volume_i < 0x1000000)
+ vol->scale_samples = scale_samples_u8_small;
+ else
+ vol->scale_samples = scale_samples_u8;
+ break;
+ case AV_SAMPLE_FMT_S16:
+ if (volume_i < 0x10000)
+ vol->scale_samples = scale_samples_s16_small;
+ else
+ vol->scale_samples = scale_samples_s16;
+ break;
+ case AV_SAMPLE_FMT_S32:
+ vol->scale_samples = scale_samples_s32;
+ break;
+ case AV_SAMPLE_FMT_FLT:
+ vol->samples_align = 4;
+ break;
+ case AV_SAMPLE_FMT_DBL:
+ vol->samples_align = 8;
+ break;
+ }
+}
+int volume_set(VolumeContext *vol, double volume)
+{
+ vol->volume = volume;
+ vol->volume_last = -1.0f;
+ scaler_init(vol);
+ return 0;
+}
+void volume_scale(VolumeContext *vol, AVFrame *frame)
+{
+ int planar, planes, plane_size, p;
+ planar = av_sample_fmt_is_planar(frame->format);
+ planes = planar ? frame->ch_layout.nb_channels : 1;
+ plane_size = frame->nb_samples * (planar ? 1 : frame->ch_layout.nb_channels);
+ if (frame->format == AV_SAMPLE_FMT_S16 ||
+ frame->format == AV_SAMPLE_FMT_S16P) {
+ int32_t vol_isrc = (int32_t)(vol->volume_last * 256 + 0.5);
+ int32_t volume_i = (int32_t)(vol->volume * 256 + 0.5);
+ if (volume_i != vol_isrc) {
+ for (p = 0; p < planes; p++) {
+ vol->fade_samples(frame->extended_data[p],
+ frame->extended_data[p],
+ frame->nb_samples, planar ? 1 : frame->ch_layout.nb_channels,
+ volume_i, vol_isrc);
+ }
+ } else {
+ for (p = 0; p < planes; p++) {
+ vol->scale_samples(frame->extended_data[p],
+ frame->extended_data[p],
+ plane_size, volume_i);
+ }
+ }
+ vol->volume_last = vol->volume;
+ } else if (frame->format == AV_SAMPLE_FMT_FLT ||
+ frame->format == AV_SAMPLE_FMT_FLTP) {
+ for (p = 0; p < planes; p++) {
+ vol->fdsp->vector_fmul_scalar((float *)frame->extended_data[p],
+ (float *)frame->extended_data[p],
+ vol->volume, plane_size);
+ }
+ } else {
+ for (p = 0; p < planes; p++) {
+ vol->fdsp->vector_dmul_scalar((double *)frame->extended_data[p],
+ (double *)frame->extended_data[p],
+ vol->volume, plane_size);
+ }
+ }
+}
+int volume_init(VolumeContext *vol, enum AVSampleFormat sample_fmt)
+{
+ vol->sample_fmt = sample_fmt;
+ vol->volume_last = -1.0f;
+ vol->volume = 1.0f;
+ vol->fdsp = avpriv_float_dsp_alloc(0);
+ if (!vol->fdsp)
+ return AVERROR(ENOMEM);
+ scaler_init(vol);
+ vol->fade_samples = fade_samples_s16_small;
+ return 0;
+}
+void volume_uninit(VolumeContext *vol)
+{
+ av_freep(&vol->fdsp);
+}
diff --git a/volume.h b/volume.h
new file mode 100644
index 0000000000..141e839e90
--- /dev/null
+++ b/volume.h
@@ -0,0 +1,44 @@
+
+/*
+ * 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
+ * audio volume for src filter
+ */
+#ifndef LIBAVFILTER_VOLUME_H
+#define LIBAVFILTER_VOLUME_H
+#include <stdint.h>
+#include "libavutil/samplefmt.h"
+#include "libavutil/float_dsp.h"
+#include "libavutil/frame.h"
+typedef struct VolumeContext {
+ AVFloatDSPContext *fdsp;
+ enum AVSampleFormat sample_fmt;
+ int samples_align;
+ double volume_last;
+ double volume;
+ void (*scale_samples)(uint8_t *dst, const uint8_t *src, int nb_samples,
+ int volume);
+ void (*fade_samples)(int16_t *dst, const int16_t *src,
+ int nb_samples, int chs, int16_t dst_volume, int16_t src_volume);
+} VolumeContext;
+int volume_init(VolumeContext *vol, enum AVSampleFormat sample_fmt);
+void volume_scale(VolumeContext *vol, AVFrame *frame);
+int volume_set(VolumeContext *vol, double volume);
+void volume_uninit(VolumeContext *vol);
+#endif /* LIBAVFILTER_VOLUME_H */
--
2.34.1
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