feat: 动态链接到 opus 和 alsa 基础库，完成音频录制播放和编解码

apps/hello/src/audio/recorder.rs

@@ -0,0 +1,37 @@
+use alsa::pcm::{PCM, HwParams, Format, Access};
+use alsa::Direction;
+use anyhow::{Result, Context};
+use crate::config::AudioConfig;
+
+pub struct AudioRecorder {
+    pcm: PCM,
+}
+
+impl AudioRecorder {
+    pub fn new(config: &AudioConfig) -> Result<Self> {
+        let pcm = PCM::new(&config.capture_device, Direction::Capture, false)
+            .context("Failed to open capture PCM device")?;
+        
+        setup_pcm(&pcm, config.sample_rate, config.channels)?;
+        Ok(Self { pcm })
+    }
+
+    pub fn read(&self, buffer: &mut [i16]) -> Result<usize> {
+        self.pcm.io_i16()?.readi(buffer).context("Failed to read from capture device")
+    }
+}
+
+fn setup_pcm(pcm: &PCM, sample_rate: u32, channels: u16) -> Result<()> {
+    let hwp = HwParams::any(pcm).context("Failed to get HwParams")?;
+    hwp.set_access(Access::RWInterleaved)?;
+    hwp.set_format(Format::s16())?;
+    hwp.set_rate(sample_rate, alsa::ValueOr::Nearest)?;
+    hwp.set_channels(channels as u32)?;
+    pcm.hw_params(&hwp).context("Failed to set HwParams")?;
+    
+    let swp = pcm.sw_params_current()?;
+    pcm.sw_params(&swp)?;
+    pcm.prepare()?;
+    Ok(())
+}
+