Omit status updates for null streams

changelog.md

@@ -12,6 +12,7 @@
 - Server: Check open syscall error in PipeStream::do_connect (PR #1150)
 - Server: Tweak Airplay support (#1102)
 - Server: Lower log severity for shairport-sync (Issue #891)
+- Server: Emits notifications for streams with codec=null (Issue #1205)
 - Improve connect handling in meta_mopidy.py
 - Fix cppcheck issues
 
@@ -20,7 +21,7 @@
 - CI: Build debian bookworm and bullseye packages for amd64, arm and arm64
 - CI: Add cppcheck static analysis
 - Update documentation (PR #1130, PR #1067)
-- Delete deprecated Makefiles, CMake is the only buildsystem
+- Delete deprecated Makefiles, CMake is the only supported buildsystem
 - Snapweb: Update to v0.7.0
 
 _Johannes Pohl <snapcast@badaix.de>  Sun, 24 Mar 2024 00:13:37 +0200_

server/encoder/null_encoder.hpp

@@ -1,6 +1,6 @@
 /***
     This file is part of snapcast
-    Copyright (C) 2014-2020  Johannes Pohl
+    Copyright (C) 2014-2024  Johannes Pohl
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -23,6 +23,15 @@
 namespace encoder
 {
 
+/// Null Encoder class
+/**
+ * Dummy encoder that will not encode any PcmChunk and thus will also never call
+ * "Encoder::encoded_callback_", i.e. the "OnEncodedCallback" to report any encoded data
+ * to the listener.
+ * Typically used as input stream for a MetaStream, which will do it's own encoding.
+ * Streams that use the null encoder cannot be listened to directly, nor they are visible
+ * on the RPC interface.
+ */
 class NullEncoder : public Encoder
 {
 public:

server/streamreader/stream_manager.cpp

@@ -1,6 +1,6 @@
 /***
     This file is part of snapcast
-    Copyright (C) 2014-2022  Johannes Pohl
+    Copyright (C) 2014-2024  Johannes Pohl
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -77,22 +77,31 @@ PcmStreamPtr StreamManager::addStream(StreamUri& streamUri)
     //		LOG(DEBUG) << "key: '" << kv.first << "' value: '" << kv.second << "'\n";
     PcmStreamPtr stream(nullptr);
 
+    PcmStream::Listener* listener = pcmListener_;
+    if ((streamUri.query[kUriCodec] == "null") && (streamUri.scheme != "meta"))
+    {
+        // Streams with null codec are "invisible" and will not report any updates to the listener.
+        // If the stream is used as input for a Meta stream, then the meta stream will add himself
+        // as another listener to the stream, so that updates are indirect reported through it.
+        listener = nullptr;
+    }
+
     if (streamUri.scheme == "pipe")
     {
-        stream = make_shared<PipeStream>(pcmListener_, io_context_, settings_, streamUri);
+        stream = make_shared<PipeStream>(listener, io_context_, settings_, streamUri);
     }
     else if (streamUri.scheme == "file")
     {
-        stream = make_shared<FileStream>(pcmListener_, io_context_, settings_, streamUri);
+        stream = make_shared<FileStream>(listener, io_context_, settings_, streamUri);
     }
     else if (streamUri.scheme == "process")
     {
-        stream = make_shared<ProcessStream>(pcmListener_, io_context_, settings_, streamUri);
+        stream = make_shared<ProcessStream>(listener, io_context_, settings_, streamUri);
     }
 #ifdef HAS_ALSA
     else if (streamUri.scheme == "alsa")
     {
-        stream = make_shared<AlsaStream>(pcmListener_, io_context_, settings_, streamUri);
+        stream = make_shared<AlsaStream>(listener, io_context_, settings_, streamUri);
     }
 #endif
     else if ((streamUri.scheme == "spotify") || (streamUri.scheme == "librespot"))
@@ -101,7 +110,7 @@ PcmStreamPtr StreamManager::addStream(StreamUri& streamUri)
         // that all constructors of all parent classes also use the overwritten sample
         // format.
         streamUri.query[kUriSampleFormat] = "44100:16:2";
-        stream = make_shared<LibrespotStream>(pcmListener_, io_context_, settings_, streamUri);
+        stream = make_shared<LibrespotStream>(listener, io_context_, settings_, streamUri);
     }
     else if (streamUri.scheme == "airplay")
     {
@@ -109,15 +118,15 @@ PcmStreamPtr StreamManager::addStream(StreamUri& streamUri)
         // that all constructors of all parent classes also use the overwritten sample
         // format.
         streamUri.query[kUriSampleFormat] = "44100:16:2";
-        stream = make_shared<AirplayStream>(pcmListener_, io_context_, settings_, streamUri);
+        stream = make_shared<AirplayStream>(listener, io_context_, settings_, streamUri);
     }
     else if (streamUri.scheme == "tcp")
     {
-        stream = make_shared<TcpStream>(pcmListener_, io_context_, settings_, streamUri);
+        stream = make_shared<TcpStream>(listener, io_context_, settings_, streamUri);
     }
     else if (streamUri.scheme == "meta")
     {
-        stream = make_shared<MetaStream>(pcmListener_, streams_, io_context_, settings_, streamUri);
+        stream = make_shared<MetaStream>(listener, streams_, io_context_, settings_, streamUri);
     }
     else
     {
@@ -210,8 +219,11 @@ json StreamManager::toJson() const
 {
     json result = json::array();
     for (const auto& stream : streams_)
+    {
+        // A stream with "null" codec will only serve as input for a meta stream, i.e. is not a "stand alone" stream
         if (stream->getCodec() != "null")
             result.push_back(stream->toJson());
+    }
     return result;
 }