fix: stub codec2 FFI for web build using conditional exports

This commit is contained in:
Janez T
2026-03-04 19:19:40 +01:00
parent d6077d1588
commit efab2cd057
3 changed files with 162 additions and 89 deletions

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@@ -1,89 +1,2 @@
import 'dart:typed_data';
import 'package:codec2_flutter/codec2_flutter.dart';
import 'package:flutter/foundation.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.mode3200: return Codec2Mode.mode3200;
case VoicePacketMode.mode1600: return Codec2Mode.mode1600;
case VoicePacketMode.mode1400: return Codec2Mode.mode1400;
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 {
void _ensureCodec2Supported() {
if (kIsWeb ||
(defaultTargetPlatform != TargetPlatform.iOS &&
defaultTargetPlatform != TargetPlatform.android)) {
throw UnsupportedError('Codec2 is enabled only on iOS and Android.');
}
}
/// Encode [pcm] (Int16 samples, 8000 Hz mono) with [mode].
/// Returns the raw Codec2-encoded bytes.
Future<Uint8List> encode(Int16List pcm, VoicePacketMode mode) {
_ensureCodec2Supported();
return Codec2.encodeInIsolate(pcm, codec2ModeFor(mode));
}
/// Decode [codec2Bytes] back to Int16 PCM (8000 Hz mono) with [mode].
Future<Int16List> decode(Uint8List codec2Bytes, VoicePacketMode mode) {
_ensureCodec2Supported();
return 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 {
_ensureCodec2Supported();
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;
}
}
export 'voice_codec_service_stub.dart'
if (dart.library.io) 'voice_codec_service_io.dart';

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@@ -0,0 +1,89 @@
import 'dart:typed_data';
import 'package:codec2_flutter/codec2_flutter.dart';
import 'package:flutter/foundation.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.mode3200: return Codec2Mode.mode3200;
case VoicePacketMode.mode1600: return Codec2Mode.mode1600;
case VoicePacketMode.mode1400: return Codec2Mode.mode1400;
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 {
void _ensureCodec2Supported() {
if (kIsWeb ||
(defaultTargetPlatform != TargetPlatform.iOS &&
defaultTargetPlatform != TargetPlatform.android)) {
throw UnsupportedError('Codec2 is enabled only on iOS and Android.');
}
}
/// Encode [pcm] (Int16 samples, 8000 Hz mono) with [mode].
/// Returns the raw Codec2-encoded bytes.
Future<Uint8List> encode(Int16List pcm, VoicePacketMode mode) {
_ensureCodec2Supported();
return Codec2.encodeInIsolate(pcm, codec2ModeFor(mode));
}
/// Decode [codec2Bytes] back to Int16 PCM (8000 Hz mono) with [mode].
Future<Int16List> decode(Uint8List codec2Bytes, VoicePacketMode mode) {
_ensureCodec2Supported();
return 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 {
_ensureCodec2Supported();
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;
}
}

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import 'dart:typed_data';
import '../utils/voice_message_parser.dart';
/// Web/unsupported platform stub — Codec2 FFI is not available.
enum Codec2Mode {
mode3200(0),
mode2400(1),
mode1600(2),
mode1400(3),
mode1300(4),
mode1200(5),
mode700c(8);
const Codec2Mode(this.c2ModeId);
final int c2ModeId;
int get framesPerSecond => (this == mode3200 || this == mode2400) ? 50 : 25;
int get samplesPerFrame => 8000 ~/ framesPerSecond;
int get bytesPerSecond {
switch (this) {
case mode3200: return 400;
case mode700c: return 100;
case mode1200: return 150;
case mode1300: return 175;
case mode1400: return 175;
case mode1600: return 200;
case mode2400: return 300;
}
}
static const int _maxBytesPerPacket = 160;
int get packetDurationMs {
final bytesPerFrame = bytesPerSecond / framesPerSecond;
final framesPerPacket = (_maxBytesPerPacket / bytesPerFrame).floor();
return (framesPerPacket * 1000 ~/ framesPerSecond);
}
}
Codec2Mode codec2ModeFor(VoicePacketMode pktMode) {
switch (pktMode) {
case VoicePacketMode.mode3200: return Codec2Mode.mode3200;
case VoicePacketMode.mode1600: return Codec2Mode.mode1600;
case VoicePacketMode.mode1400: return Codec2Mode.mode1400;
case VoicePacketMode.mode700c: return Codec2Mode.mode700c;
case VoicePacketMode.mode1200: return Codec2Mode.mode1200;
case VoicePacketMode.mode1300: return Codec2Mode.mode1300;
case VoicePacketMode.mode2400: return Codec2Mode.mode2400;
}
}
VoicePacketMode voiceModeForBandwidth(int radioBandwidthHz) {
if (radioBandwidthHz <= 62500) return VoicePacketMode.mode700c;
if (radioBandwidthHz <= 125000) return VoicePacketMode.mode1200;
return VoicePacketMode.mode1300;
}
class VoiceCodecService {
Future<Uint8List> encode(Int16List pcm, VoicePacketMode mode) =>
Future.error(UnsupportedError('Voice not supported on web'));
Future<Int16List> decode(Uint8List codec2Bytes, VoicePacketMode mode) =>
Future.error(UnsupportedError('Voice not supported on web'));
Future<Int16List> decodePackets(
List<VoicePacket?> packets,
VoicePacketMode mode,
) =>
Future.error(UnsupportedError('Voice not supported on web'));
}