MoonWorks/src/Video/VideoPlayer.cs

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using MoonWorks.Audio;
using MoonWorks.Graphics;

namespace MoonWorks.Video
{
	public unsafe class VideoPlayer : IDisposable
	{
		public Texture RenderTexture { get; private set; } = null;
		public VideoState State { get; private set; } = VideoState.Stopped;
		public bool Loop { get; set; }
		public float PlaybackSpeed { get; set; } = 1;

		private VideoAV1 Video = null;

		private GraphicsDevice GraphicsDevice;
		private Texture yTexture = null;
		private Texture uTexture = null;
		private Texture vTexture = null;
		private Sampler LinearSampler;

		private int currentFrame;

		private Stopwatch timer;
		private double lastTimestamp;
		private double timeElapsed;

		private Stopwatch profilingTimer = new Stopwatch();

		private bool disposed;

		public VideoPlayer(GraphicsDevice graphicsDevice, AudioDevice audioDevice)
		{
			GraphicsDevice = graphicsDevice;
			if (GraphicsDevice.VideoPipeline == null)
			{
				throw new InvalidOperationException("Missing video shaders!");
			}

			LinearSampler = new Sampler(graphicsDevice, SamplerCreateInfo.LinearClamp);

			timer = new Stopwatch();
		}

		public void Load(VideoAV1 video)
		{
			if (Video != video)
			{
				Stop();

				if (RenderTexture == null)
				{
					RenderTexture = CreateRenderTexture(GraphicsDevice, video.Width, video.Height);
				}

				if (yTexture == null)
				{
					yTexture = CreateSubTexture(GraphicsDevice, video.Width, video.Height);
				}

				if (uTexture == null)
				{
					uTexture = CreateSubTexture(GraphicsDevice, video.UVWidth, video.UVHeight);
				}

				if (vTexture == null)
				{
					vTexture = CreateSubTexture(GraphicsDevice, video.UVWidth, video.UVHeight);
				}

				if (video.Width != RenderTexture.Width || video.Height != RenderTexture.Height)
				{
					RenderTexture.Dispose();
					RenderTexture = CreateRenderTexture(GraphicsDevice, video.Width, video.Height);
				}

				if (video.Width != yTexture.Width || video.Height != yTexture.Height)
				{
					yTexture.Dispose();
					yTexture = CreateSubTexture(GraphicsDevice, video.Width, video.Height);
				}

				if (video.UVWidth != uTexture.Width || video.UVHeight != uTexture.Height)
				{
					uTexture.Dispose();
					uTexture = CreateSubTexture(GraphicsDevice, video.UVWidth, video.UVHeight);
				}

				if (video.UVWidth != vTexture.Width || video.UVHeight != vTexture.Height)
				{
					vTexture.Dispose();
					vTexture = CreateSubTexture(GraphicsDevice, video.UVWidth, video.UVHeight);
				}

				Video = video;

				InitializeDav1dStream();
			}
		}

		public void Play()
		{
			if (Video == null) { return; }

			if (State == VideoState.Playing)
			{
				return;
			}

			timer.Start();

			State = VideoState.Playing;
		}

		public void Pause()
		{
			if (Video == null) { return; }

			if (State != VideoState.Playing)
			{
				return;
			}

			timer.Stop();

			State = VideoState.Paused;
		}

		public void Stop()
		{
			if (Video == null) { return; }

			if (State == VideoState.Stopped)
			{
				return;
			}

			timer.Stop();
			timer.Reset();

			lastTimestamp = 0;
			timeElapsed = 0;

			Dav1dfile.df_reset(Video.Handle);

			State = VideoState.Stopped;
		}

		public void Unload()
		{
			Stop();
			Video = null;
		}

		public void Update()
		{
			if (Video == null) { return; }
		}

		public void Render()
		{
			if (Video == null || State == VideoState.Stopped)
			{
				return;
			}

			timeElapsed += (timer.Elapsed.TotalMilliseconds - lastTimestamp) * PlaybackSpeed;
			lastTimestamp = timer.Elapsed.TotalMilliseconds;

			int thisFrame = ((int) (timeElapsed / (1000.0 / Video.FramesPerSecond)));
			if (thisFrame > currentFrame)
			{
				profilingTimer.Restart();
				int readResult = Dav1dfile.df_readvideo(
					Video.Handle,
					thisFrame - currentFrame,
					out var yData,
					out var uData,
					out var vData,
					out var yDataLength,
					out var uvDataLength,
					out var yStride,
					out var uvStride
				);
				profilingTimer.Stop();
				System.Console.WriteLine($"Frame decoded in: {profilingTimer.Elapsed.TotalMilliseconds}");

				if (readResult == 1 || currentFrame == -1)
				{
					UpdateRenderTexture(yData, uData, vData, yDataLength, uvDataLength, yStride, uvStride);
				}

				currentFrame = thisFrame;
			}

			bool ended = Dav1dfile.df_eos(Video.Handle) == 1;
			if (ended)
			{
				timer.Stop();
				timer.Reset();

				Dav1dfile.df_reset(Video.Handle);

				if (Loop)
				{
					// Start over!
					InitializeDav1dStream();

					timer.Start();
				}
				else
				{
					State = VideoState.Stopped;
				}
			}
		}

		private void UpdateRenderTexture(IntPtr yData, IntPtr uData, IntPtr vData, uint yDataLength, uint uvDataLength, uint yStride, uint uvStride)
		{
			var commandBuffer = GraphicsDevice.AcquireCommandBuffer();

			commandBuffer.SetTextureDataYUV(
				yTexture,
				uTexture,
				vTexture,
				yData,
				uData,
				vData,
				yDataLength,
				uvDataLength,
				yStride,
				uvStride
			);

			commandBuffer.BeginRenderPass(
				new ColorAttachmentInfo(RenderTexture, Color.Black)
			);

			commandBuffer.BindGraphicsPipeline(GraphicsDevice.VideoPipeline);
			commandBuffer.BindFragmentSamplers(
				new TextureSamplerBinding(yTexture, LinearSampler),
				new TextureSamplerBinding(uTexture, LinearSampler),
				new TextureSamplerBinding(vTexture, LinearSampler)
			);

			commandBuffer.DrawPrimitives(0, 1, 0, 0);

			commandBuffer.EndRenderPass();

			GraphicsDevice.Submit(commandBuffer);
		}

		private static Texture CreateRenderTexture(GraphicsDevice graphicsDevice, int width, int height)
		{
			return Texture.CreateTexture2D(
				graphicsDevice,
				(uint) width,
				(uint) height,
				TextureFormat.R8G8B8A8,
				TextureUsageFlags.ColorTarget | TextureUsageFlags.Sampler
			);
		}

		private static Texture CreateSubTexture(GraphicsDevice graphicsDevice, int width, int height)
		{
			return Texture.CreateTexture2D(
				graphicsDevice,
				(uint) width,
				(uint) height,
				TextureFormat.R8,
				TextureUsageFlags.Sampler
			);
		}

		private void InitializeDav1dStream()
		{
			// Grab the first video frame ASAP.
			Dav1dfile.df_readvideo(
				Video.Handle,
				1,
				out var _,
				out var _,
				out var _,
				out var _,
				out var _,
				out var _,
				out var _);
			currentFrame = -1;
		}

		protected virtual void Dispose(bool disposing)
		{
			if (!disposed)
			{
				if (disposing)
				{
					// dispose managed state (managed objects)
					RenderTexture.Dispose();
					yTexture.Dispose();
					uTexture.Dispose();
					vTexture.Dispose();
				}

				disposed = true;
			}
		}

		~VideoPlayer()
		{
		    // Do not change this code. Put cleanup code in 'Dispose(bool disposing)' method
		    Dispose(disposing: false);
		}

		public void Dispose()
		{
			// Do not change this code. Put cleanup code in 'Dispose(bool disposing)' method
			Dispose(disposing: true);
			GC.SuppressFinalize(this);
		}
	}
}