From d9ace12fee24965baf6cf065691ed99c0d229ab1 Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Fri, 17 Jan 2025 20:19:51 +0100
Subject: Detect MIDI port

---
 MIDIPlayer.cpp | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 1 deletion(-)

(limited to 'MIDIPlayer.cpp')

diff --git a/MIDIPlayer.cpp b/MIDIPlayer.cpp
index f2bba8c..2c0bc6a 100644
--- a/MIDIPlayer.cpp
+++ b/MIDIPlayer.cpp
@@ -6,13 +6,19 @@
 #include <algorithm>
 #include <chrono>
 #include <iostream>
+#include <string>
 #include <thread>
+#include <unordered_set>
 
 namespace bp = boost::process;
 namespace fs = std::filesystem;
 
 using namespace std::chrono_literals;
 
+namespace {
+  std::unordered_set<std::string> supported_devices{"AudioBox 22 VSL", "CH345"};
+}
+
 MIDIPlayer::MIDIPlayer(const std::filesystem::path& path):
   m_child{},
   m_dir{path},
@@ -23,6 +29,10 @@ MIDIPlayer::MIDIPlayer(const std::filesystem::path& path):
   if (list.size() > 0) {
     m_file = list[0];
   }
+
+  init_seq();
+  iterate_ports();
+  close_seq();
 }
 
 void MIDIPlayer::start()
@@ -30,7 +40,7 @@ void MIDIPlayer::start()
   if (m_child.valid() && m_child.running()) {
     stop();
   } else {
-    m_child = bp::child(fmt::format("aplaymidi -p24 \"{}\"", m_file).c_str());//, bp::std_out > bp::null);
+    m_child = bp::child(fmt::format("aplaymidi -p{} \"{}\"", m_client, m_file).c_str());//, bp::std_out > bp::null);
   }
 }
 
@@ -87,3 +97,71 @@ std::vector<std::string> MIDIPlayer::get_filelist()
   return result;
 }
 
+void MIDIPlayer::init_seq(void)
+{
+  /* open sequencer */
+  int err = snd_seq_open(&m_seq, "default", SND_SEQ_OPEN_DUPLEX, 0);
+  if (err < 0)
+  {
+    throw std::runtime_error("snd_seq_open()");
+  }
+}
+
+void MIDIPlayer::close_seq(void)
+{
+  int err = snd_seq_close(m_seq);
+  if (err < 0)
+  {
+    throw std::runtime_error("snd_seq_close()");
+  }
+}
+
+void MIDIPlayer::iterate_ports(void)
+{
+  bool found{};
+
+  snd_seq_client_info_t *cinfo;
+  snd_seq_port_info_t *pinfo;
+
+  snd_seq_client_info_alloca(&cinfo);
+  snd_seq_port_info_alloca(&pinfo);
+
+  snd_seq_client_info_set_client(cinfo, -1);
+  while (snd_seq_query_next_client(m_seq, cinfo) >= 0) {
+    int client = snd_seq_client_info_get_client(cinfo);
+
+    snd_seq_port_info_set_client(pinfo, client);
+    snd_seq_port_info_set_port(pinfo, -1);
+    while (snd_seq_query_next_port(m_seq, pinfo) >= 0) {
+      /* port must understand MIDI messages */
+      if (!(snd_seq_port_info_get_type(pinfo)
+            & SND_SEQ_PORT_TYPE_MIDI_GENERIC))
+              continue;
+      /* we need both WRITE and SUBS_WRITE */
+      if ((snd_seq_port_info_get_capability(pinfo)
+           & (SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE))
+          != (SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE))
+              continue;
+      if (supported_devices.contains(std::string{snd_seq_client_info_get_name(cinfo)})) {
+        m_client = snd_seq_port_info_get_client(pinfo);
+        found = true;
+      }
+      //std::cout << fmt::format("DEBUG: {}", get_midi_port()) << std::endl;
+      //printf("%3d:%-3d  %-32.32s %s\n",
+      //       snd_seq_port_info_get_client(pinfo),
+      //       snd_seq_port_info_get_port(pinfo),
+      //       snd_seq_client_info_get_name(cinfo),
+      //       snd_seq_port_info_get_name(pinfo));
+    }
+  }
+
+  if (!found) {
+    throw std::runtime_error("No MIDI device found");
+  }
+}
+
+int MIDIPlayer::get_midi_port()
+{
+  return m_client;
+}
+
-- 
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