Files
meshcore-sar_android/lib/services/voice_codec_service.dart
Janez T f96d8022ac feat: add Codec2 voice messages over LoRa mesh (iOS/macOS only)
Push-to-talk voice messaging using the Codec2 ultra-low-bitrate speech
codec, transmitted as V: prefixed packets over the existing MeshCore
LoRa mesh pipeline.

Voice recording UI (long-press send button or + menu) is gated behind
Platform.isIOS || Platform.isMacOS since the `record` package only
supports microphone capture on those platforms in this build.

Key changes:
- VoiceRecorderService: streams 8kHz mono PCM chunks via `record` package
- VoicePlayerService: decodes Codec2 bytes to WAV and plays via audioplayers
- VoiceCodecService: async Codec2 encode/decode in background isolates
- VoiceProvider: reassembles multi-packet sessions, drives playback
- VoiceMessageBubble: shows packet progress, play/stop controls
- MessagesProvider: detects V: prefix, routes to VoiceProvider
- MessagesTab: PTT long-press gesture + recording indicator (iOS/macOS)
- Message model: isVoice + voiceId fields for session tracking
- Auto-selects codec mode from radio bandwidth (700C/1200/1300 bps)
- codec2_flutter + meshcore_client switched from path to git deps
2026-02-28 19:19:46 +01:00

73 lines
2.7 KiB
Dart

import 'dart:typed_data';
import 'package:codec2_flutter/codec2_flutter.dart';
import '../utils/voice_message_parser.dart';
export 'package:codec2_flutter/codec2_flutter.dart' show Codec2Mode;
/// Maps [VoicePacketMode] to the [Codec2Mode] enum from the FFI plugin.
Codec2Mode codec2ModeFor(VoicePacketMode pktMode) {
switch (pktMode) {
case VoicePacketMode.mode700c: return Codec2Mode.mode700c;
case VoicePacketMode.mode1200: return Codec2Mode.mode1200;
case VoicePacketMode.mode1300: return Codec2Mode.mode1300;
case VoicePacketMode.mode2400: return Codec2Mode.mode2400;
}
}
/// Selects the [VoicePacketMode] best suited for a given LoRa radio bandwidth.
///
/// Call with [radioBandwidthHz] from the device's radio params
/// (e.g. 125000 for 125 kHz).
VoicePacketMode voiceModeForBandwidth(int radioBandwidthHz) {
if (radioBandwidthHz <= 62500) return VoicePacketMode.mode700c;
if (radioBandwidthHz <= 125000) return VoicePacketMode.mode1200;
return VoicePacketMode.mode1300;
}
/// High-level codec service that provides async Codec2 encode/decode
/// executed in a background isolate so the UI thread is never blocked.
class VoiceCodecService {
/// Encode [pcm] (Int16 samples, 8000 Hz mono) with [mode].
/// Returns the raw Codec2-encoded bytes.
Future<Uint8List> encode(Int16List pcm, VoicePacketMode mode) =>
Codec2.encodeInIsolate(pcm, codec2ModeFor(mode));
/// Decode [codec2Bytes] back to Int16 PCM (8000 Hz mono) with [mode].
Future<Int16List> decode(Uint8List codec2Bytes, VoicePacketMode mode) =>
Codec2.decodeInIsolate(codec2Bytes, codec2ModeFor(mode));
/// Decode and concatenate multiple [packets] into a single PCM Int16List.
/// Packets with null/missing entries are substituted with silence.
Future<Int16List> decodePackets(
List<VoicePacket?> packets,
VoicePacketMode mode,
) async {
final c2Mode = codec2ModeFor(mode);
final c2 = Codec2.create(c2Mode);
final spf = c2.samplesPerFrame;
c2.destroy();
// Estimate total samples (use actual data or silence per missing packet)
final all = <Int16List>[];
for (final pkt in packets) {
if (pkt == null || pkt.codec2Data.isEmpty) {
// Silence for missing packet — duration approximated by mode
final silenceSamples = (codec2ModeFor(mode).framesPerSecond) * spf;
all.add(Int16List(silenceSamples));
} else {
final decoded = await Codec2.decodeInIsolate(pkt.codec2Data, c2Mode);
all.add(decoded);
}
}
final total = all.fold<int>(0, (sum, l) => sum + l.length);
final result = Int16List(total);
var offset = 0;
for (final chunk in all) {
result.setRange(offset, offset + chunk.length, chunk);
offset += chunk.length;
}
return result;
}
}