gstreamer/subprojects/gst-plugins-base/gst/volume/gstvolume.h
Roman Lebedev 8b1500d7ff volume: support arbitrarily-large positive gains
The current limit is `x10`, which allows just `+20 dB` of gain.

While it may seem sufficient, this came up as a problem
in a real-world, non-specially-engineered situation,
in strawberry's EBU R 128 loudness normalization.
(https://github.com/strawberrymusicplayer/strawberry/pull/1216)

There is an audio track (that was not intentionally engineered that way),
that has integrated loudness of `-38 LUFS`,
and if we want to normalize it's loudness to e.g. `-16 LUFS`,
which is a very reasonable thing to do,
we need to apply gain of `+22 dB`,
which is larger than `+20 dB`, and we fail...

I think it should allow at least `+96 dB` of gain,
and therefore should be at `10^(96/20) ~= 63096`.

But, i don't see why we need to put any specific restriction
on that parameter in the first place, other than the fact
that the fixed-point multiplication scheme does not support volume
larger than 15x-ish.

So let's just implement a floating-point fall-back path
that does not involve fixed-point multiplication
and lift the restriction altogether?

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5063>
2023-08-07 13:17:45 +00:00

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/* -*- c-basic-offset: 2 -*-
* vi:si:et:sw=2:sts=8:ts=8:expandtab
*
* GStreamer
* Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
* Copyright (C) 2010 Sebastian Dröge <sebastian.droege@collabora.co.uk>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#ifndef __GST_VOLUME_H__
#define __GST_VOLUME_H__
#include <gst/gst.h>
#include <gst/base/gstbasetransform.h>
#include <gst/audio/streamvolume.h>
#include <gst/audio/audio.h>
#include <gst/audio/gstaudiofilter.h>
G_BEGIN_DECLS
#define GST_TYPE_VOLUME (gst_volume_get_type())
G_DECLARE_FINAL_TYPE (GstVolume, gst_volume, GST, VOLUME, GstAudioFilter)
/**
* GstVolume:
*
* Opaque data structure.
*/
struct _GstVolume {
GstAudioFilter element;
void (*process)(GstVolume*, gpointer, guint);
void (*process_controlled)(GstVolume*, gpointer, gdouble *, guint, guint);
gboolean mute;
gfloat volume;
gboolean current_mute;
gdouble current_volume;
gint64 current_vol_i32;
gint64 current_vol_i24; /* the _i(nt) values get synchronized with the */
gint64 current_vol_i16; /* the _i(nt) values get synchronized with the */
gint64 current_vol_i8; /* the _i(nt) values get synchronized with the */
GList *tracklist;
gboolean negotiated;
gboolean *mutes;
guint mutes_count;
gdouble *volumes;
guint volumes_count;
};
GST_ELEMENT_REGISTER_DECLARE (volume);
G_END_DECLS
#endif /* __GST_VOLUME_H__ */