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Fix clipping with Opus files without ReplayGain tags when there's less than 5 dB headroom #2526

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Fix clipping with Opus files without ReplayGain tags when there's less than 5 dB headroom #2526

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2dbf8a4
opus: do not add 5 dB to Opus header playback gain
horazont Jun 27, 2026
8fdd025
opus: move EbuR128 -> ReplayGain to OpusTags
horazont Jun 27, 2026
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20 changes: 5 additions & 15 deletions src/decoder/plugins/OpusDecoderPlugin.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -47,17 +47,6 @@ IsOpusTags(const ogg_packet &packet) noexcept
return packet.bytes >= 8 && memcmp(packet.packet, "OpusTags", 8) == 0;
}

/**
* Convert an EBU R128 value to ReplayGain.
*/
static constexpr float
EbuR128ToReplayGain(float ebu_r128) noexcept
{
/* add 5dB to compensate for the different reference levels
between ReplayGain (89dB) and EBU R128 (-23 LUFS) */
return ebu_r128 + 5;
}

static bool
mpd_opus_init([[maybe_unused]] const ConfigBlock &block)
{
Expand Down Expand Up @@ -282,11 +271,12 @@ MPDOpusDecoder::HandleTags(const ogg_packet &packet)

if (rgi.IsDefined()) {
/* submit all valid EBU R128 values with output_gain
applied */
applied. conversion from EBU R128 -> ReplayGain
happened in ScanOpusTags already. */
if (rgi.track.IsDefined())
rgi.track.gain += EbuR128ToReplayGain(output_gain);
rgi.track.gain += output_gain;
if (rgi.album.IsDefined())
rgi.album.gain += EbuR128ToReplayGain(output_gain);
rgi.album.gain += output_gain;
client.SubmitReplayGain(&rgi);
submitted_replay_gain = true;
}
Expand All @@ -312,7 +302,7 @@ MPDOpusDecoder::HandleAudio(const ogg_packet &packet)
gain" value */
ReplayGainInfo rgi;
rgi.Clear();
rgi.track.gain = EbuR128ToReplayGain(output_gain);
rgi.track.gain = output_gain;
client.SubmitReplayGain(&rgi);
submitted_replay_gain = true;
}
Expand Down
15 changes: 13 additions & 2 deletions src/decoder/plugins/OpusTags.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,17 @@

using std::string_view_literals::operator""sv;

/**
* Convert an EBU R128 value to ReplayGain.
*/
static constexpr float
EbuR128ToReplayGain(float ebu_r128) noexcept
{
/* add 5dB to compensate for the different reference levels
between ReplayGain (89dB) and EBU R128 (-23 LUFS) */
return ebu_r128 + 5;
}

[[gnu::pure]]
static TagType
ParseOpusTagName(std::string_view name) noexcept
Expand Down Expand Up @@ -47,14 +58,14 @@ ScanOneOpusTag(std::string_view name, std::string_view value,
dB */

if (const auto i = ParseInteger<int_least32_t>(value))
rgi->track.gain = float(*i) / 256.0f;
rgi->track.gain = EbuR128ToReplayGain(float(*i) / 256.0f);
} else if (rgi != nullptr &&
StringIsEqualIgnoreCase(name, "R128_ALBUM_GAIN"sv)) {
/* R128_ALBUM_GAIN is a Q7.8 fixed point number in
dB */

if (const auto i = ParseInteger<int_least32_t>(value))
rgi->album.gain = float(*i) / 256.0f;
rgi->album.gain = EbuR128ToReplayGain(float(*i) / 256.0f);
}

handler.OnPair(name, value);
Expand Down