Flutter playing sounds sequentially, but with a gap between them

I have a requirement to play .mp3 sound files one after another, with no break or gap in between. While there is no issue in playing the sound files sequentially, there is a pause between them which is unacceptable given the requirements.

I have tried three solutions, one using the standard flutter audioplayer, and two using the just_audio package.

The code for each three is as follows:

  // STANDARD AUDIO PLAYER
  import 'package:audioplayers/audioplayers.dart';
  ...

  AudioPlayer player = AudioPlayer();
  ...
  void _playAudio(
      {required List<String> files, required int currentIndex}) async {
    String fileName =
        'audio/${files[currentIndex].toLowerCase()}.mp3';
    await player.play(AssetSource(fileName), mode: PlayerMode.lowLatency);

    player.onPlayerComplete.listen((event) {
      if (currentIndex + 1 >= files.length) {
        return;
      }
      _playAudio(files: files, currentIndex: ++currentIndex);
    });
  }


  // JUST_AUDIO
  import 'package:just_audio/just_audio.dart';
  ...
  AudioPlayer player = AudioPlayer();
  ...
  void _playAudio(
      {required List<String> files, required int currentIndex}) async {
    await AudioPlayer.clearAssetCache();
    for (final file in files) {
      await player
          .setAsset('assets/audio/${file.mp3');
      await player.play();
      await player.pause();
    }
  }


  // JUST AUDIO GAPLESS
  import 'package:just_audio/just_audio.dart';
  ...
  AudioPlayer player = AudioPlayer();
  ...
  void _playAudio(
      {required List<String> files, required int currentIndex}) async {
    final playlist = ConcatenatingAudioSource(
      // Start loading next item just before reaching it
      useLazyPreparation: false,

      children: [],
    );
    for (final file in files) {
      playlist.add(AudioSource.asset(
          'assets/audio/${file}.mp3'));
    }
    await player.setAudioSource(playlist);
    await player.play();
}

Each of the above play the sounds, but only with a gap in between of approximately a second.

Does anyone know why this is, or have another approach?

Thanks very much

Solution

Two options from my point of view:

1. Set all your assets before you play

the code is not 100% correct, but you get my point

void _playAudio(
    {required List<String> files, required int currentIndex}) async {
  await AudioPlayer.clearAssetCache(); // is this gonna work?

  final List<AudioPlayer> players = []; // array of players - yes, multiple players in the memory

  for (final file in files) {
    final AudioPlayer player = AudioPlayer(); // create the instance of one
    await player.setAsset('assets/audio/${file.mp3}'); // set asset for the one player
    players.add(player); // add it to the array
  }

  for (final player in players) {
    await player.play(); // play the all players
    await player.pause();
    // delete a cache somehow?
  }
}

2. Use different isolates for loading the asset

Here is the official doc