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Engine: pipe-in the EBU R 128 loudness normalization gain stuff

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The idea is that Integrated Loudness is an integral part
of the song, much like knowing it's beginning / ending
in the file, and we must handle it the exact same way,
and pipe it through all the way.

At the same time, `EngineBase` knows Target Level (from settings),
and these two combined tell us the Gain needed to normalize the
Loudness of the particular Song (`EngineBase::Load()` does that).
So the actual backend only needs to handle the Volume.

We don't currently support changing Target Level on the fly.
We don't currently support changing Loudness-normalizing Gain on the fly.

This does not handle the case when the song is loaded from URL
and thus the EBU R 128 measures, that exist, are not nessesairly correct.
This commit is contained in:
Roman Lebedev
2023-06-27 05:05:01 +03:00
committed by Jonas Kvinge
parent 40ef3191fc
commit 13d6cf201f
10 changed files with 63 additions and 19 deletions
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24
src/engine/enginebase.cpp
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@@ -43,6 +43,7 @@ EngineBase::EngineBase(QObject *parent)
volume_(100),
beginning_nanosec_(0),
end_nanosec_(0),
ebur128_loudness_normalizing_gain_db_(0.0),
scope_(kScopeSize),
buffering_(false),
equalizer_enabled_(false),
@@ -51,6 +52,8 @@ EngineBase::EngineBase(QObject *parent)
rg_preamp_(0.0),
rg_fallbackgain_(0.0),
rg_compression_(true),
ebur128_loudness_normalization_(false),
ebur128_target_level_lufs_(-23.0),
buffer_duration_nanosec_(BackendSettingsPage::kDefaultBufferDuration * kNsecPerMsec),
buffer_low_watermark_(BackendSettingsPage::kDefaultBufferLowWatermark),
buffer_high_watermark_(BackendSettingsPage::kDefaultBufferHighWatermark),
@@ -104,7 +107,7 @@ QString EngineBase::Description(const Type type) {
}
bool EngineBase::Load(const QUrl &media_url, const QUrl &stream_url, const TrackChangeFlags, const bool force_stop_at_end, const quint64 beginning_nanosec, const qint64 end_nanosec) {
bool EngineBase::Load(const QUrl &media_url, const QUrl &stream_url, const TrackChangeFlags, const bool force_stop_at_end, const quint64 beginning_nanosec, const qint64 end_nanosec, const std::optional<double> ebur128_integrated_loudness_lufs) {
Q_UNUSED(force_stop_at_end);
@@ -113,15 +116,27 @@ bool EngineBase::Load(const QUrl &media_url, const QUrl &stream_url, const Track
beginning_nanosec_ = beginning_nanosec;
end_nanosec_ = end_nanosec;
ebur128_loudness_normalizing_gain_db_ = 0.0;
if (ebur128_loudness_normalization_ && ebur128_integrated_loudness_lufs) {
auto computeGain_dB = [](double source_dB, double target_dB) {
// Let's suppose the `source_dB` is -12 dB, while `target_dB` is -23 dB.
// In that case, we'd need to apply -11 dB of gain, which is computed as:
// -12 dB + x dB = -23 dB --> x dB = -23 dB - (-12 dB)
return target_dB - source_dB;
};
ebur128_loudness_normalizing_gain_db_ = computeGain_dB(*ebur128_integrated_loudness_lufs, ebur128_target_level_lufs_);
}
about_to_end_emitted_ = false;
return true;
}
bool EngineBase::Play(const QUrl &media_url, const QUrl &stream_url, const TrackChangeFlags flags, const bool force_stop_at_end, const quint64 beginning_nanosec, const qint64 end_nanosec, const quint64 offset_nanosec) {
bool EngineBase::Play(const QUrl &media_url, const QUrl &stream_url, const TrackChangeFlags flags, const bool force_stop_at_end, const quint64 beginning_nanosec, const qint64 end_nanosec, const quint64 offset_nanosec, const std::optional<double> ebur128_integrated_loudness_lufs) {
if (!Load(media_url, stream_url, flags, force_stop_at_end, beginning_nanosec, end_nanosec)) {
if (!Load(media_url, stream_url, flags, force_stop_at_end, beginning_nanosec, end_nanosec, ebur128_integrated_loudness_lufs)) {
return false;
}
@@ -167,6 +182,9 @@ void EngineBase::ReloadSettings() {
rg_fallbackgain_ = s.value("rgfallbackgain", 0.0).toDouble();
rg_compression_ = s.value("rgcompression", true).toBool();
ebur128_loudness_normalization_ = s.value("ebur128_loudness_normalization", false).toBool();
ebur128_target_level_lufs_ = s.value("ebur128_target_level_lufs", -23.0).toDouble();
fadeout_enabled_ = s.value("FadeoutEnabled", false).toBool();
crossfade_enabled_ = s.value("CrossfadeEnabled", false).toBool();
autocrossfade_enabled_ = s.value("AutoCrossfadeEnabled", false).toBool();