[Linux/rust] Implemented high-res microphone support

.github/workflows/ci-linux-rust.yml

@@ -21,7 +21,8 @@ jobs:
       - name: Install dependencies
         run: |
           sudo apt-get update
-          sudo apt-get install -y pkg-config libdbus-1-dev libpulse-dev appstream just libfuse2
+          sudo apt-get install -y pkg-config libdbus-1-dev libpulse-dev appstream just libfuse2 \
+            libavutil-dev libavcodec-dev libavformat-dev libavfilter-dev libavdevice-dev libswresample-dev libswscale-dev
 
       - name: Install AppImage tools
         run: |

linux-rust/Cargo.toml

@@ -13,6 +13,7 @@ dbus = "0.9.10"
 hex = "0.4.3"
 iced = { version = "0.14.0", features = ["tokio", "image"] }
 libpulse-binding = "2.30.1"
+libpulse-simple-binding = "2.29.0"
 ksni = "0.3.1"
 image = "0.25.8"
 imageproc = "0.26.1"
@@ -22,6 +23,9 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 aes = "0.9.0-rc.4"
 futures = "0.3.32"
+# AAC-ELD decode for the hi-res microphone. System libavcodec/libavutil via
+# pkg-config (no bundled build); avformat/swscale/etc. are not needed.
+ffmpeg-sys-next = { version = "8.1", default-features = false, features = ["avcodec"] }
 
 [profile.release]
 opt-level = "s"

linux-rust/flatpak/me.kavishdevar.librepods.yaml

@@ -7,6 +7,14 @@ sdk-extensions:
 
 command: librepods
 
+# Hi-res microphone deps (verified present in org.freedesktop.Platform 25.08):
+#   - libavcodec.so.61 / libavutil.so.59 (FFmpeg 7.1) for AAC-ELD decode.
+#     ffmpeg-sys-next auto-detects this version at build time, so no pin needed.
+#   - libpulse-simple.so.0 for the PCM playback stream.
+# The virtual mic is created over the existing --socket=pulseaudio (module load
+# + playback are protocol calls; no extra finish-args, no pactl/pw-cat needed).
+# Build note: ffmpeg-sys-next runs bindgen, which needs libclang from the SDK.
+
 finish-args:
   - --socket=wayland
   - --socket=fallback-x11

linux-rust/src/audio/agc.rs

@@ -0,0 +1,47 @@
+//! AGC (Automatic Gain Control) for audio processing.
+
+pub struct Agc {
+    envelope: f32,
+    gain: f32,
+}
+
+impl Agc {
+    const TARGET: f32 = 0.25; // ≈ -12 dBFS
+    const MAX_GAIN: f32 = 8.0; // +18 dB
+    const ATTACK: f32 = 0.02;
+    const RELEASE: f32 = 0.001;
+
+    pub fn new() -> Self {
+        Self {
+            envelope: 0.0,
+            gain: 1.0,
+        }
+    }
+
+    pub fn process(&mut self, samples: &mut [i16]) {
+        for s in samples {
+            let x = *s as f32 / 32768.0;
+            let level = x.abs();
+
+            if level > self.envelope {
+                self.envelope += (level - self.envelope) * Self::ATTACK;
+            } else {
+                self.envelope += (level - self.envelope) * Self::RELEASE;
+            }
+
+            // Target gain
+            let desired = (Self::TARGET / self.envelope.max(1e-4)).min(Self::MAX_GAIN);
+
+            // Smooth gain
+            self.gain += (desired - self.gain) * 0.01;
+
+            // Apply gain
+            let mut y = x * self.gain;
+
+            // Soft limiter
+            y = y.tanh();
+
+            *s = (y * 32767.0) as i16;
+        }
+    }
+}