Merge branch 'gain-fragment' of github.com:vpatkov/MPD

Author: MaxKellermann

NEWS

@@ -7,6 +7,8 @@ ver 0.25 (not yet released)
   - vgmstream: new plugin
 * output
   - pipewire: add option "reconnect_stream"
+* player
+  - support replay gain parameter in stream URI
 * switch to C++23
 * require Meson 1.2
 

doc/user.rst

@@ -678,6 +678,14 @@ prevents `Bit-perfect playback`_).  To use a hardware mixer, set
 ``replay_gain_handler`` to ``mixer`` in the ``audio_output`` section
 (see :ref:`config_audio_output` for details).
 
+The ``gain`` URL fragment can be used to apply ReplayGain tags to
+Internet radios, which helps to normalize volume across different
+radios, e.g.::
+
+    mpc add 'http://radio.example.com/stream#gain=-3.5'
+
+This will set "track" and "album" ReplayGain tags for the stream to -3.5 dB.
+
 Simple Volume Normalization
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

src/decoder/Thread.cxx

@@ -21,8 +21,10 @@
 #include "util/Domain.hxx"
 #include "util/ScopeExit.hxx"
 #include "util/StringCompare.hxx"
+#include "util/UriQueryParser.hxx"
 #include "thread/Name.hxx"
 #include "tag/ApeReplayGain.hxx"
+#include "tag/ReplayGainParser.hxx"
 #include "Log.hxx"
 
 #include <stdexcept>
@@ -277,6 +279,19 @@ LoadReplayGain(DecoderClient &client, InputStream &is)
 	ReplayGainInfo info;
 	if (replay_gain_ape_read(is, info))
 		client.SubmitReplayGain(&info);
+
+	const char *fragment = uri_get_fragment(is.GetURI());
+	if (fragment != nullptr) {
+		const auto gain = UriFindRawQueryParameter(fragment, "gain");
+		if (gain.data() != nullptr) {
+			if (ParseReplayGainTag(info, "replaygain_track_gain",
+					std::string(gain).c_str())) {
+				info.album.gain = info.track.gain;
+				info.album.peak = info.track.peak = 0.0;
+				client.SubmitReplayGain(&info);
+			}
+		}
+	}
 }
 
 /**