superstar_v2/Services/MediaService.cs

using LibVLCSharp.Shared;

namespace DualScreenDemo.Services
{
    public class MediaService : IDisposable
    {
        private readonly LibVLC _libVLC;
        private readonly MediaPlayer _mediaPlayerPrimary;
        private readonly MediaPlayer _mediaPlayerSecondary;
        private Media? _media;
        private Media? _mediaNoAudio;
        private bool _disposed;

        public MediaService()
        {
            Core.Initialize();
            _libVLC = new LibVLC(
                "--aout=directsound",
                //"--avcodec-hw=dxva2",
                "--network-caching=300",
                "--file-caching=300",
                "--audio-time-stretch"
            );

            _mediaPlayerPrimary = new MediaPlayer(_libVLC);
            _mediaPlayerSecondary = new MediaPlayer(_libVLC);
        }

        #region Player Setup
        public void SetVideoFormPrimary(nint handle, int width, int height)
        {
            _mediaPlayerPrimary.Hwnd = handle;
            _mediaPlayerPrimary.AspectRatio = $"{width}:{height}";
            _mediaPlayerPrimary.Scale = 0; // 保持原比例
        }

        public void SetVideoFormSecondary(nint handle, int width, int height)
        {
            _mediaPlayerSecondary.Hwnd = handle;
            _mediaPlayerSecondary.AspectRatio = $"{width}:{height}";
            _mediaPlayerSecondary.Scale = 0;
        }
        #endregion

        #region Playback
        public MediaPlayer PrimaryPlayer => _mediaPlayerPrimary;
        public MediaPlayer SecondaryPlayer => _mediaPlayerSecondary;
        public bool IsPlaying => _mediaPlayerSecondary.IsPlaying;

        public bool IsAtEnd()
        {
            var duration = _mediaPlayerSecondary.Media?.Duration ?? 0;
            var time = _mediaPlayerSecondary.Time;
            return duration > 0 && Math.Abs(duration - time) < 1000;
        }

        public void LoadMedia(string filePath, int audioTrackIndex = 0)
        {
            _media?.Dispose();

            // 建立一個完整有聲音的 Media 給 secondary 播放器
            _media = new Media(_libVLC, filePath, FromType.FromPath);
            _media.AddOption(":audio-output=directsound");
            _media.AddOption($":audio-track={audioTrackIndex}");
            
            // 同時準備給 primary 播放器用的無聲音版本 Media
            _mediaNoAudio?.Dispose();
            _mediaNoAudio = new Media(_libVLC, filePath, FromType.FromPath);
            _mediaNoAudio.AddOption(":no-audio");  // 關閉聲音輸出
        }

        public async Task PlayAsync()
        {
            if (_media == null || _mediaNoAudio == null) return;

            _mediaPlayerPrimary.Play(_mediaNoAudio);  // 播放無聲音版本
            await Task.Delay(100);
            _mediaPlayerSecondary.Play(_media);              // 播放有聲音版本

            await SyncPlayersAsync();
        }
        public async Task Play()
        {
            _mediaPlayerPrimary.Play();  // 播放無聲音版本
            await Task.Delay(100);
            _mediaPlayerSecondary.Play();              // 播放有聲音版本

            await SyncPlayersAsync();
        }

        public void Pause()
        {
            _mediaPlayerPrimary.Pause();
            _mediaPlayerSecondary.Pause();
        }

        public void Stop()
        {
            _mediaPlayerPrimary.Stop();
            _mediaPlayerSecondary.Stop();
        }
        #endregion

        #region Sync
        private async Task SyncPlayersAsync()
        {
            while (_mediaPlayerPrimary.IsPlaying && _mediaPlayerSecondary.IsPlaying)
            {
                var t1 = _mediaPlayerPrimary.Time;
                var t2 = _mediaPlayerSecondary.Time;

                if (Math.Abs(t1 - t2) > 100)
                    _mediaPlayerSecondary.Time = t1;

                await Task.Delay(200);
            }
        }
        #endregion

        #region Mute
        public bool Mute(bool isMuted)
        { 
            _mediaPlayerSecondary.Mute = isMuted;
            return _mediaPlayerSecondary.Mute;
        }
        #endregion

        #region Volume
        public void SetVolume(int volume)
        {
            _mediaPlayerPrimary.Volume = volume;
            _mediaPlayerSecondary.Volume = volume;
        }
        public int GetVolume() => _mediaPlayerSecondary?.Volume ?? 0;
        #endregion

        #region Audio Tracks
        public List<TrackDescription> GetAudioTracks()
        {
            var result = new List<TrackDescription>();
            var media = _mediaPlayerSecondary.Media;

            if (media == null) return result;

            if (!media.IsParsed)
                media.Parse(MediaParseOptions.ParseLocal);

            var tracks = media.Tracks;
            if (tracks == null) return result;

            foreach (var track in tracks.Where(t => t.TrackType == TrackType.Audio))
            {
                result.Add(new TrackDescription
                {
                    Id = track.Id,
                    Name = !string.IsNullOrEmpty(track.Language) ? track.Language : $"Audio Track {track.Id}"
                });
            }
            return result;
        }

        public async Task SetAudioTrackToAsync(int trackIndex)
        {
            var audioTracks = GetAudioTracks();
            if (trackIndex < 0 || trackIndex >= audioTracks.Count) return;

            if (!_mediaPlayerSecondary.IsPlaying)
            {
                _mediaPlayerSecondary.Play();
                await Task.Delay(500);
            }

            _mediaPlayerSecondary.SetAudioTrack(audioTracks[trackIndex].Id);
            await Task.Delay(300);
        }
        #endregion

        #region Dispose
        public void Dispose()
        {
            if (_disposed) return;

            _mediaPlayerPrimary?.Dispose();
            _mediaPlayerSecondary?.Dispose();
            _media?.Dispose();
            _mediaNoAudio?.Dispose();
            _libVLC?.Dispose();

            _mediaNoAudio = null;
            _media = null;
            _disposed = true;
        }
        #endregion
    }

    public class TrackDescription
    {
        public int Id { get; set; }
        public string Name { get; set; } = string.Empty;
    }
}