mirror of
https://github.com/dz0ny/meshcore-sar.git
synced 2026-08-11 16:30:28 +00:00
90 lines
3.3 KiB
Dart
90 lines
3.3 KiB
Dart
import 'dart:typed_data';
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import 'package:codec2_flutter/codec2_flutter.dart';
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import 'package:flutter/foundation.dart';
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import '../utils/voice_message_parser.dart';
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export 'package:codec2_flutter/codec2_flutter.dart' show Codec2Mode;
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/// Maps [VoicePacketMode] to the [Codec2Mode] enum from the FFI plugin.
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Codec2Mode codec2ModeFor(VoicePacketMode pktMode) {
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switch (pktMode) {
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case VoicePacketMode.mode3200: return Codec2Mode.mode3200;
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case VoicePacketMode.mode1600: return Codec2Mode.mode1600;
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case VoicePacketMode.mode1400: return Codec2Mode.mode1400;
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case VoicePacketMode.mode700c: return Codec2Mode.mode700c;
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case VoicePacketMode.mode1200: return Codec2Mode.mode1200;
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case VoicePacketMode.mode1300: return Codec2Mode.mode1300;
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case VoicePacketMode.mode2400: return Codec2Mode.mode2400;
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}
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}
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/// Selects the [VoicePacketMode] best suited for a given LoRa radio bandwidth.
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///
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/// Call with [radioBandwidthHz] from the device's radio params
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/// (e.g. 125000 for 125 kHz).
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VoicePacketMode voiceModeForBandwidth(int radioBandwidthHz) {
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if (radioBandwidthHz <= 62500) return VoicePacketMode.mode700c;
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if (radioBandwidthHz <= 125000) return VoicePacketMode.mode1200;
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return VoicePacketMode.mode1300;
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}
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/// High-level codec service that provides async Codec2 encode/decode
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/// executed in a background isolate so the UI thread is never blocked.
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class VoiceCodecService {
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void _ensureCodec2Supported() {
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if (kIsWeb ||
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(defaultTargetPlatform != TargetPlatform.iOS &&
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defaultTargetPlatform != TargetPlatform.android)) {
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throw UnsupportedError('Codec2 is enabled only on iOS and Android.');
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}
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}
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/// Encode [pcm] (Int16 samples, 8000 Hz mono) with [mode].
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/// Returns the raw Codec2-encoded bytes.
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Future<Uint8List> encode(Int16List pcm, VoicePacketMode mode) {
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_ensureCodec2Supported();
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return Codec2.encodeInIsolate(pcm, codec2ModeFor(mode));
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}
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/// Decode [codec2Bytes] back to Int16 PCM (8000 Hz mono) with [mode].
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Future<Int16List> decode(Uint8List codec2Bytes, VoicePacketMode mode) {
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_ensureCodec2Supported();
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return Codec2.decodeInIsolate(codec2Bytes, codec2ModeFor(mode));
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}
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/// Decode and concatenate multiple [packets] into a single PCM Int16List.
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/// Packets with null/missing entries are substituted with silence.
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Future<Int16List> decodePackets(
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List<VoicePacket?> packets,
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VoicePacketMode mode,
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) async {
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_ensureCodec2Supported();
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final c2Mode = codec2ModeFor(mode);
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final c2 = Codec2.create(c2Mode);
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final spf = c2.samplesPerFrame;
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c2.destroy();
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// Estimate total samples (use actual data or silence per missing packet)
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final all = <Int16List>[];
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for (final pkt in packets) {
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if (pkt == null || pkt.codec2Data.isEmpty) {
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// Silence for missing packet — duration approximated by mode
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final silenceSamples = (codec2ModeFor(mode).framesPerSecond) * spf;
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all.add(Int16List(silenceSamples));
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} else {
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final decoded = await Codec2.decodeInIsolate(pkt.codec2Data, c2Mode);
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all.add(decoded);
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}
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}
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final total = all.fold<int>(0, (sum, l) => sum + l.length);
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final result = Int16List(total);
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var offset = 0;
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for (final chunk in all) {
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result.setRange(offset, offset + chunk.length, chunk);
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offset += chunk.length;
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}
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return result;
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}
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}
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