feat(proxy-engine): add Rust-based outbound calling, WebRTC bridging, and voicemail handling

rust/crates/proxy-engine/src/recorder.rs

@@ -0,0 +1,132 @@
+//! Audio recorder — receives RTP packets and writes a WAV file.
+
+use codec_lib::TranscodeState;
+use std::path::Path;
+
+/// Active recording session.
+pub struct Recorder {
+    writer: hound::WavWriter<std::io::BufWriter<std::fs::File>>,
+    transcoder: TranscodeState,
+    source_pt: u8,
+    total_samples: u64,
+    sample_rate: u32,
+    max_samples: Option<u64>,
+    file_path: String,
+}
+
+impl Recorder {
+    /// Create a new recorder that writes to a WAV file.
+    /// `source_pt` is the RTP payload type of the incoming audio.
+    /// `max_duration_ms` optionally limits the recording length.
+    pub fn new(
+        file_path: &str,
+        source_pt: u8,
+        max_duration_ms: Option<u64>,
+    ) -> Result<Self, String> {
+        // Ensure parent directory exists.
+        if let Some(parent) = Path::new(file_path).parent() {
+            std::fs::create_dir_all(parent)
+                .map_err(|e| format!("create dir: {e}"))?;
+        }
+
+        let sample_rate = 8000u32; // Record at 8kHz (standard telephony)
+        let spec = hound::WavSpec {
+            channels: 1,
+            sample_rate,
+            bits_per_sample: 16,
+            sample_format: hound::SampleFormat::Int,
+        };
+
+        let writer = hound::WavWriter::create(file_path, spec)
+            .map_err(|e| format!("create WAV {file_path}: {e}"))?;
+
+        let transcoder = TranscodeState::new().map_err(|e| format!("codec init: {e}"))?;
+
+        let max_samples = max_duration_ms.map(|ms| (sample_rate as u64 * ms) / 1000);
+
+        Ok(Self {
+            writer,
+            transcoder,
+            source_pt,
+            total_samples: 0,
+            sample_rate,
+            max_samples,
+            file_path: file_path.to_string(),
+        })
+    }
+
+    /// Process an incoming RTP packet (full packet with header).
+    /// Returns true if recording should continue, false if max duration reached.
+    pub fn process_rtp(&mut self, data: &[u8]) -> bool {
+        if data.len() <= 12 {
+            return true; // Too short, skip.
+        }
+
+        let pt = data[1] & 0x7F;
+        // Skip telephone-event (DTMF) packets.
+        if pt == 101 {
+            return true;
+        }
+
+        let payload = &data[12..];
+        if payload.is_empty() {
+            return true;
+        }
+
+        // Decode to PCM.
+        let (pcm, rate) = match self.transcoder.decode_to_pcm(payload, self.source_pt) {
+            Ok(result) => result,
+            Err(_) => return true, // Decode failed, skip packet.
+        };
+
+        // Resample to 8kHz if needed.
+        let pcm_8k = if rate != self.sample_rate {
+            match self.transcoder.resample(&pcm, rate, self.sample_rate) {
+                Ok(r) => r,
+                Err(_) => return true,
+            }
+        } else {
+            pcm
+        };
+
+        // Write samples.
+        for &sample in &pcm_8k {
+            if let Err(_) = self.writer.write_sample(sample) {
+                return false;
+            }
+            self.total_samples += 1;
+
+            if let Some(max) = self.max_samples {
+                if self.total_samples >= max {
+                    return false; // Max duration reached.
+                }
+            }
+        }
+
+        true
+    }
+
+    /// Stop recording and finalize the WAV file.
+    pub fn stop(self) -> RecordingResult {
+        let duration_ms = if self.sample_rate > 0 {
+            (self.total_samples * 1000) / self.sample_rate as u64
+        } else {
+            0
+        };
+
+        // Writer is finalized on drop (writes RIFF header sizes).
+        drop(self.writer);
+
+        RecordingResult {
+            file_path: self.file_path,
+            duration_ms,
+            total_samples: self.total_samples,
+        }
+    }
+}
+
+pub struct RecordingResult {
+    pub file_path: String,
+    pub duration_ms: u64,
+    pub total_samples: u64,
+}