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Source/Editor/Viewport/Previews/AudioClipPreview.cs

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+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+using System;
+using System.Threading.Tasks;
+using FlaxEngine;
+using FlaxEngine.GUI;
+
+namespace FlaxEditor.Viewport.Previews
+{
+    /// <summary>
+    /// Audio clip PCM data editor preview.
+    /// </summary>
+    /// <seealso cref="FlaxEngine.GUI.ContainerControl" />
+    public class AudioClipPreview : ContainerControl
+    {
+        /// <summary>
+        /// The audio clip drawing modes.
+        /// </summary>
+        public enum DrawModes
+        {
+            /// <summary>
+            /// Fills the whole control area with the full clip duration.
+            /// </summary>
+            Fill,
+
+            /// <summary>
+            /// Draws single audio clip. Uses the view scale parameter.
+            /// </summary>
+            Single,
+
+            /// <summary>
+            /// Draws the looped audio clip. Uses the view scale parameter.
+            /// </summary>
+            Looped,
+        };
+
+        private readonly object _locker = new object();
+        private AudioClip _asset;
+        private float[] _pcmData;
+        private AudioDataInfo _pcmInfo;
+
+        /// <summary>
+        /// Gets or sets the clip to preview.
+        /// </summary>
+        public AudioClip Asset
+        {
+            get => _asset;
+            set
+            {
+                lock (_locker)
+                {
+                    if (_asset == value)
+                        return;
+
+                    _asset = value;
+                    _pcmData = null;
+
+                    if (_asset)
+                    {
+                        // Use async task to gather PCM data (engine loads it from the asset)
+                        Task.Run(DownloadData);
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Gets a value indicating whether audio data has been fetched from the asset (done as an async task). It is required to be valid in order to draw the audio buffer preview.
+        /// </summary>
+        public bool HasData
+        {
+            get
+            {
+                lock (_locker)
+                {
+                    return _pcmData != null;
+                }
+            }
+        }
+
+        /// <summary>
+        /// The draw mode.
+        /// </summary>
+        public DrawModes DrawMode = DrawModes.Fill;
+
+        /// <summary>
+        /// The view scale parameter. Increase it to zoom in the audio. Usage depends on the current <see cref="DrawMode"/>.
+        /// </summary>
+        public float ViewScale = 1.0f;
+
+        /// <summary>
+        /// The color of the audio PCM data spectrum.
+        /// </summary>
+        public Color Color = Color.White;
+
+        /// <summary>
+        /// The audio units per second (on time axis).
+        /// </summary>
+        public static readonly float UnitsPerSecond = 100.0f;
+
+        /// <inheritdoc />
+        public override void Draw()
+        {
+            base.Draw();
+
+            lock (_locker)
+            {
+                var info = _pcmInfo;
+                if (_asset == null || _pcmData == null || info.NumSamples == 0)
+                    return;
+                var height = Height;
+                var width = Width;
+                var samplesPerChannel = info.NumSamples / info.NumChannels;
+                var length = (float)samplesPerChannel / info.SampleRate;
+                var color = Color;
+                if (!EnabledInHierarchy)
+                    color *= 0.4f;
+
+                // Compute the scaled y-value used to render the channel data
+                float sampleYScale = height / info.NumChannels;
+
+                // Compute amount of samples that are contained in the view
+                float unitsPerSecond = UnitsPerSecond * ViewScale;
+                float clipDefaultWidth = length * unitsPerSecond;
+                float clipsInView = width / clipDefaultWidth;
+                float clipWidth;
+                uint samplesPerIndex;
+                switch (DrawMode)
+                {
+                case DrawModes.Fill:
+                    clipsInView = 1.0f;
+                    clipWidth = width;
+                    samplesPerIndex = (uint)(samplesPerChannel / width);
+                    break;
+                case DrawModes.Single:
+                    clipsInView = Mathf.Min(clipsInView, 1.0f);
+                    clipWidth = clipDefaultWidth;
+                    samplesPerIndex = (uint)(info.SampleRate / unitsPerSecond) * info.NumChannels;
+                    break;
+                case DrawModes.Looped:
+                    clipWidth = width / clipsInView;
+                    samplesPerIndex = (uint)(info.SampleRate / unitsPerSecond) * info.NumChannels;
+                    break;
+                default: throw new ArgumentOutOfRangeException();
+                }
+                const uint maxSamplesPerIndex = 64;
+                uint samplesPerIndexDiff = Math.Max(1, samplesPerIndex / Math.Min(samplesPerIndex, maxSamplesPerIndex));
+
+                // Render each clip separately
+                for (uint clipIndex = 0; clipIndex < Mathf.CeilToInt(clipsInView); clipIndex++)
+                {
+                    var clipX = clipWidth * clipIndex;
+                    var clipRight = Mathf.Min(width, clipX + clipWidth);
+
+                    // Render each channel separately so outer loop is the sound wave channel index
+                    for (uint channelIndex = 0; channelIndex < info.NumChannels; channelIndex++)
+                    {
+                        uint currentSample = channelIndex;
+                        float yCenter = Y + ((2 * channelIndex) + 1) * height / (2.0f * info.NumChannels);
+
+                        // Loop through each pixel (in x direction)
+                        for (float pixelX = clipX; pixelX < clipRight; pixelX++)
+                        {
+                            // Reset the sample sum and num samples in pixel for each pixel
+                            float samplesSum = 0;
+                            int samplesInPixel = 0;
+
+                            // Loop through all pixels in this x-frame and sum all audio data
+                            uint samplesEnd = Math.Min(currentSample + samplesPerIndex, info.NumSamples);
+                            for (uint sampleIndex = currentSample; sampleIndex < samplesEnd; sampleIndex += samplesPerIndexDiff)
+                            {
+                                samplesSum += Mathf.Abs(_pcmData[sampleIndex]);
+                                samplesInPixel++;
+                            }
+                            currentSample = samplesEnd;
+                            if (samplesInPixel > 0)
+                            {
+                                float averageSampleValue = samplesSum / samplesInPixel;
+                                float averageSampleValueScaled = averageSampleValue * sampleYScale;
+
+                                // Don't try to draw anything if the audio data was too quiet
+                                if (averageSampleValueScaled > 0.1f)
+                                {
+                                    // Draw vertical line mirrored around x-axis for channel equal to average sample value height
+                                    Render2D.DrawLine(new Vector2(pixelX, yCenter - averageSampleValueScaled), new Vector2(pixelX, yCenter + averageSampleValueScaled), color);
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Downloads the audio clip raw PCM data. Use it from async thread to prevent blocking,
+        /// </summary>
+        private void DownloadData()
+        {
+            var asset = _asset;
+
+            if (!asset)
+            {
+                Editor.LogWarning("Failed to get audio clip PCM data. Missing asset.");
+                return;
+            }
+
+            float[] data;
+            AudioDataInfo dataInfo;
+            try
+            {
+                asset.ExtractDataFloat(out data, out dataInfo);
+            }
+            catch (Exception ex)
+            {
+                Editor.LogWarning("Failed to get audio clip PCM data. " + ex.Message);
+                Editor.LogWarning(ex);
+                return;
+            }
+
+            if (data.Length != dataInfo.NumSamples)
+            {
+                Editor.LogWarning("Failed to get audio clip PCM data. Invalid samples count. Returned buffer has other size.");
+            }
+
+            lock (_locker)
+            {
+                // If asset has been modified during data fetching, ignore it
+                if (_asset == asset)
+                {
+                    _pcmData = data;
+                    _pcmInfo = dataInfo;
+                }
+            }
+        }
+    }
+}