fix(microphone): resolve ALSA cards from sysfs

cmvr-es/devices/microphone/ffmpeg_microphone/CMakeLists.txt

@@ -10,7 +10,6 @@ add_library(cmvr_es::device::ffmpeg_microphone ALIAS ffmpeg_microphone)
 target_link_libraries(ffmpeg_microphone PRIVATE
         avfilter
         avdevice
-        -lasound
         -lpulse
         cmvr_es::proto
 )

cmvr-es/devices/microphone/ffmpeg_microphone/src/microphone_device_discovery.cpp

@@ -2,6 +2,7 @@
 
 #include <cerrno>
 #include <cstdlib>
+#include <fstream>
 #include <limits>
 #include <memory>
 #include <optional>
@@ -12,7 +13,6 @@
 #include <utility>
 
 extern "C" {
-#include <alsa/asoundlib.h>
 #include <libavdevice/avdevice.h>
 #include <libavutil/error.h>
 #include <pulse/pulseaudio.h>
@@ -53,6 +53,22 @@ std::optional<int> parseNonNegativeInt(const char* value)
     return static_cast<int>(parsed);
 }
 
+std::optional<int> findAlsaCardIndex(const std::string& card_name)
+{
+    constexpr int kMaxAlsaCards = 256;
+    const auto numeric_card_index = parseNonNegativeInt(card_name.c_str());
+    for (int index = 0; index < kMaxAlsaCards; ++index) {
+        std::ifstream id_file(
+            "/sys/class/sound/card" + std::to_string(index) + "/id");
+        std::string id;
+        if (id_file && std::getline(id_file, id) &&
+            (id == card_name || (numeric_card_index && *numeric_card_index == index))) {
+            return index;
+        }
+    }
+    return std::nullopt;
+}
+
 std::optional<AlsaEndpoint> parseFfmpegCaptureEndpoint(const char* device_name)
 {
     constexpr std::string_view kPlugHardwarePrefix = "plughw:";
@@ -78,12 +94,12 @@ std::optional<AlsaEndpoint> parseFfmpegCaptureEndpoint(const char* device_name)
     const std::string card_name(name.substr(card_key + kCardKey.size(),
                                             card_end - card_key - kCardKey.size()));
     const std::string device_text(name.substr(device_key + kDeviceKey.size()));
-    const int card_index = snd_card_get_index(card_name.c_str());
+    const auto card_index = findAlsaCardIndex(card_name);
     const auto device_index = parseNonNegativeInt(device_text.c_str());
-    if (card_index < 0 || !device_index) {
+    if (!card_index || !device_index) {
         return std::nullopt;
     }
-    return AlsaEndpoint{card_index, *device_index};
+    return AlsaEndpoint{*card_index, *device_index};
 }
 
 struct PulseSourceQuery {