decoder/mpcdec: fix bogus ReplayGain values

Apparently, libmpcdec sets gain/peak variables to zero if they are not present. This clashes with our formula and results in bogus values which cause noise during playback. Closes https://github.com/MusicPlayerDaemon/MPD/issues/640

decoder/mpcdec: fix bogus ReplayGain values
92495d2b · Max Kellermann · 9270829b · 92495d2b · 92495d2b
Commit 92495d2b authored Sep 13, 2019 by Max Kellermann
Show whitespace changes
Inline Side-by-side

Showing with 6 additions and 0 deletions

NEWS NEWS +1 -0

MpcdecDecoderPlugin.cxx src/decoder/plugins/MpcdecDecoderPlugin.cxx +5 -0

No files found.
--- a/NEWS
+++ b/NEWS
 ver 0.21.15 (not yet released)
 * decoder
  - dsdiff, dsf: fix displayed bit rate
+  - mpcdec: fix bogus ReplayGain values
 * output
  - solaris: fix build with glibc 2.30


--- a/src/decoder/plugins/MpcdecDecoderPlugin.cxx
+++ b/src/decoder/plugins/MpcdecDecoderPlugin.cxx
@@ -141,8 +141,12 @@ static constexpr ReplayGainTuple
 ImportMpcdecReplayGain(mpc_uint16_t gain, mpc_uint16_t peak) noexcept
 {
 	auto t = ReplayGainTuple::Undefined();
+
+	if (gain != 0 && peak != 0) {
 		t.gain = MPC_OLD_GAIN_REF - (gain  / 256.);
 		t.peak = pow(10, peak / 256. / 20) / 32767;
+	}
+
 	return t;
 }

@@ -187,6 +191,7 @@ mpcdec_decode(DecoderClient &client, InputStream &is)

 	{
 		const auto rgi = ImportMpcdecReplayGain(info);
+		if (rgi.IsDefined())
 			client.SubmitReplayGain(&rgi);
 	}