feat: 完善 OTG UAC 音频支持

src/config/schema/uac.rs

@@ -0,0 +1,78 @@
+use serde::{Deserialize, Serialize};
+use typeshare::typeshare;
+
+use crate::error::{AppError, Result};
+
+/// Configuration for the USB Audio Class microphone gadget.
+#[typeshare]
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(default)]
+pub struct UacConfig {
+    pub enabled: bool,
+    pub sample_rate: u32,
+    pub channels: u8,
+}
+
+impl Default for UacConfig {
+    fn default() -> Self {
+        Self {
+            enabled: false,
+            sample_rate: 48_000,
+            channels: 2,
+        }
+    }
+}
+
+impl UacConfig {
+    pub fn validate(&self) -> Result<()> {
+        // Older configurations stored zero-valued placeholders while UAC was
+        // disabled. Accept them until the feature is enabled and normalized.
+        if !self.enabled {
+            return Ok(());
+        }
+        if self.sample_rate != 48_000 {
+            return Err(AppError::BadRequest(format!(
+                "unsupported UAC sample rate {} (expected 48000)",
+                self.sample_rate
+            )));
+        }
+        if self.channels != 2 {
+            return Err(AppError::BadRequest(format!(
+                "unsupported UAC channel count {} (expected 2)",
+                self.channels
+            )));
+        }
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn defaults_match_the_audio_transport() {
+        let config = UacConfig::default();
+        assert_eq!(config.sample_rate, 48_000);
+        assert_eq!(config.channels, 2);
+        assert!(config.validate().is_ok());
+    }
+
+    #[test]
+    fn rejects_formats_the_transport_cannot_convert() {
+        assert!(UacConfig {
+            enabled: true,
+            sample_rate: 44_100,
+            ..Default::default()
+        }
+        .validate()
+        .is_err());
+        assert!(UacConfig {
+            enabled: true,
+            channels: 1,
+            ..Default::default()
+        }
+        .validate()
+        .is_err());
+    }
+}