Revise device configuration logic and settings

The ALSA device scanner no longer inserts default sample rates when it cannot read them, preventing invalid frequency choices

Jack server settings now accept independent input and output devices during construction

The latency test utility was updated to handle separate input and output device parameters and display them accordingly

The help text for the latency tool documents the new usage with optional output device specification

Device lists in the configuration dialog are sorted to prefer devices supporting capture and playback, then USB devices, while refresh preserves existing selections

src/PiLatencyMain.cpp

@@ -57,9 +57,9 @@ void PrintHelp()
     pp << "Copyright (c) 2022 Robin Davies\n";
     pp << "\n";
     pp << Indent(0) << "Syntax\n\n";
-    pp << Indent(2) << "pipedal_latency_test [<options>] <device-name>\n\n";
-    pp << "where <device-name> is the name of an ALSA device. Typically this should be the name of a hardware "
-         "device (a device name starting with 'hw:').\n\n";
+    pp << Indent(2) << "pipedal_latency_test [<options>] <input-device> [<output-device>]\n\n";
+    pp << "where <input-device> is the name of an ALSA capture device and <output-device> is the name of a playback device. "
+         "If <output-device> is omitted, the input device will be used for both capture and playback. Typically the device names start with 'hw:'.\n\n";
     pp << Indent(0) << "Options\n\n";
     pp << Indent(15);
 
@@ -95,7 +95,8 @@ void PrintHelp()
 
     pp << Indent(0) << "Examples\n\n";
     pp << Indent(2) << "pipedal_latency_test --list\n\n";
-    pp << Indent(2) << "pipedal_latency_test hw:M2\n\n";
+    pp << Indent(2) << "pipedal_latency_test hw:M2\n";
+    pp << Indent(2) << "pipedal_latency_test hw:M2 hw:Device2\n\n";
 }
 
 void ListDevices()
@@ -138,7 +139,8 @@ public:
 private:
     AudioDriver *audioDriver = nullptr;
 
-    const std::string &deviceId;
+    const std::string &inputDeviceId;
+    const std::string &outputDeviceId;
     ChannelsT inputChannels;
     ChannelsT outputChannels;
     uint32_t sampleRate;
@@ -147,11 +149,13 @@ private:
 
 public:
     AlsaTester(
-        const std::string &deviceId,
+        const std::string &inputDeviceId,
+        const std::string &outputDeviceId,
         const ChannelsT &inputChannels,
         const ChannelsT &outputChannels,
         uint32_t sampleRate, int bufferSize, int buffers)
-        : deviceId(deviceId),
+        : inputDeviceId(inputDeviceId),
+          outputDeviceId(outputDeviceId),
           sampleRate(sampleRate),
           inputChannels(inputChannels),
           outputChannels(outputChannels),
@@ -186,7 +190,7 @@ public:
         TestResult result;
         try
         {
-            JackServerSettings serverSettings(deviceId, sampleRate, bufferSize, buffers);
+            JackServerSettings serverSettings(inputDeviceId, outputDeviceId, sampleRate, bufferSize, buffers);
 
             JackConfiguration jackConfiguration;
             jackConfiguration.AlsaInitialize(serverSettings);
@@ -403,12 +407,13 @@ public:
 };
 
 TestResult RunLatencyTest(
-    const std::string deviceId,
+    const std::string inputDeviceId,
+    const std::string outputDeviceId,
     const ChannelsT &inputChannels,
     const ChannelsT &outputChannels,
     uint32_t sampleRate, int bufferSize, int buffers)
 {
-    AlsaTester tester(deviceId, inputChannels, outputChannels, sampleRate, bufferSize, buffers);
+     AlsaTester tester(inputDeviceId, outputDeviceId, inputChannels, outputChannels, sampleRate, bufferSize, buffers);
     return tester.Test();
 }
 
@@ -428,13 +433,14 @@ static std::string overheadDisplay(float value)
 }
 
 void RunLatencyTest(
-    const std::string &deviceId,
+    const std::string &inputDeviceId,
+    const std::string &outputDeviceId,
     const ChannelsT &inputChannels,
     const ChannelsT &outputChannels,
     uint32_t sampleRate)
 {
     PrettyPrinter pp;
-    pp << "Device: " << deviceId << " Rate: " << sampleRate << "\n\n";
+     pp << "Input: " << inputDeviceId << "  Output: " << outputDeviceId << "  Rate: " << sampleRate << "\n\n";
 
     const int SIZE_COLUMN_WIDTH = 8;
     const int BUFFERS_COLUMN_WIDTH = 20;
@@ -461,7 +467,7 @@ void RunLatencyTest(
 
         for (auto bufferCount : bufferCounts)
         {
-            auto result = RunLatencyTest(deviceId, inputChannels,outputChannels, sampleRate, bufferSize, bufferCount);
+             auto result = RunLatencyTest(inputDeviceId, outputDeviceId, inputChannels,outputChannels, sampleRate, bufferSize, bufferCount);
 
             pp.Column(column);
             column += BUFFERS_COLUMN_WIDTH;
@@ -556,11 +562,14 @@ std:
         {
             ListDevices();
         }
-        else if (parser.Arguments().size() == 1)
+        else if (parser.Arguments().size() >= 1 && parser.Arguments().size() <= 2)
         {
             inputChannels = ParseChannels(strInputChannels);
-            outputChannels = ParseChannels(strInputChannels);
-            RunLatencyTest(parser.Arguments()[0], inputChannels, outputChannels, sampleRate);
+            outputChannels = ParseChannels(strOutputChannels);
+
+            std::string inDev  = parser.Arguments()[0];
+            std::string outDev = parser.Arguments().size() == 2 ? parser.Arguments()[1] : inDev;
+            RunLatencyTest(inDev, outDev, inputChannels, outputChannels, sampleRate);
         }
         else
         {