Sdl backend (#670)

* [audio] added sdl audio backend and in-tree atrac9 decoder * [input] replaced per-platform pad readers with sdl gamepad input * [video] added sdl window and host display plumbing * [gui] added host display options and per-game render settings * [bink] synced host movie playback to the guest audio clock * [cpu] hooked windows write faults into guest image tracking * [perf] added guest and render profiling, reserved host cpu lanes * [kernel] fixed stale pthread mutex handle alias * [host] wired the sdl session, save-data paths and project references * [audio] hoisted ajm trace stackalloc out of its loop * [video] Add guest image sync setting * [build] Strip native symbols * reuse
2026-07-30 22:49:53 +08:00 · 2026-07-28 03:33:26 +03:00
parent b4cc5f88ca
commit 2b6bd5a532
111 changed files with 9846 additions and 4479 deletions
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: MIT
+#nullable disable
+using System;
+using LibAtrac9.Utilities;
+
+namespace LibAtrac9
+{
+    /// <summary>
+    /// Decodes an ATRAC9 stream into 16-bit PCM.
+    /// </summary>
+    public class Atrac9Decoder
+    {
+        /// <summary>
+        /// The config data for the current ATRAC9 stream.
+        /// </summary>
+        public Atrac9Config Config { get; private set; }
+
+        private Frame Frame { get; set; }
+        private BitReader Reader { get; set; }
+        private bool _initialized;
+
+        /// <summary>
+        /// Sets up the decoder to decode an ATRAC9 stream based on the information in <paramref name="configData"/>.
+        /// </summary>
+        /// <param name="configData">A 4-byte value containing information about the ATRAC9 stream.</param>
+        public void Initialize(byte[] configData)
+        {
+            Config = new Atrac9Config(configData);
+            Frame = new Frame(Config);
+            Reader = new BitReader(null);
+            _initialized = true;
+        }
+
+        /// <summary>
+        /// Decodes one superframe of ATRAC9 data.
+        /// </summary>
+        /// <param name="atrac9Data">The ATRAC9 data to decode. The array must be at least
+        /// <see cref="Config"/>.<see cref="Atrac9Config.SuperframeBytes"/> bytes long.</param>
+        /// <param name="pcmOut">A buffer that the decoded PCM data will be placed in.
+        /// The array must have dimensions of at least [<see cref="Config"/>.<see cref="Atrac9Config.ChannelCount"/>]
+        /// [<see cref="Config"/>.<see cref="Atrac9Config.SuperframeSamples"/>].</param>
+        public void Decode(byte[] atrac9Data, short[][] pcmOut)
+        {
+            if (!_initialized) throw new InvalidOperationException("Decoder must be initialized before decoding.");
+
+            ValidateDecodeBuffers(atrac9Data, pcmOut);
+            Reader.SetBuffer(atrac9Data);
+            DecodeSuperFrame(pcmOut);
+        }
+
+        private void ValidateDecodeBuffers(byte[] atrac9Buffer, short[][] pcmBuffer)
+        {
+            if (atrac9Buffer == null) throw new ArgumentNullException(nameof(atrac9Buffer));
+            if (pcmBuffer == null) throw new ArgumentNullException(nameof(pcmBuffer));
+
+            if (atrac9Buffer.Length < Config.SuperframeBytes)
+            {
+                throw new ArgumentException("ATRAC9 buffer is too small");
+            }
+
+            if (pcmBuffer.Length < Config.ChannelCount)
+            {
+                throw new ArgumentException("PCM buffer is too small");
+            }
+
+            for (int i = 0; i < Config.ChannelCount; i++)
+            {
+                if (pcmBuffer[i]?.Length < Config.SuperframeSamples)
+                {
+                    throw new ArgumentException("PCM buffer is too small");
+                }
+            }
+        }
+
+        private void DecodeSuperFrame(short[][] pcmOut)
+        {
+            for (int i = 0; i < Config.FramesPerSuperframe; i++)
+            {
+                Frame.FrameIndex = i;
+                DecodeFrame(Reader, Frame);
+                PcmFloatToShort(pcmOut, i * Config.FrameSamples);
+                Reader.AlignPosition(8);
+            }
+        }
+
+        private void PcmFloatToShort(short[][] pcmOut, int start)
+        {
+            int endSample = start + Config.FrameSamples;
+            int channelNum = 0;
+            foreach (Block block in Frame.Blocks)
+            {
+                foreach (Channel channel in block.Channels)
+                {
+                    double[] pcmSrc = channel.Pcm;
+                    short[] pcmDest = pcmOut[channelNum++];
+                    for (int d = 0, s = start; s < endSample; d++, s++)
+                    {
+                        double sample = pcmSrc[d];
+                        // Not using Math.Round because it's ~20x slower on 64-bit
+                        int roundedSample = (int)Math.Floor(sample + 0.5);
+                        pcmDest[s] = Helpers.Clamp16(roundedSample);
+                    }
+                }
+            }
+        }
+
+        private static void DecodeFrame(BitReader reader, Frame frame)
+        {
+            Unpack.UnpackFrame(reader, frame);
+
+            foreach (Block block in frame.Blocks)
+            {
+                Quantization.DequantizeSpectra(block);
+                Stereo.ApplyIntensityStereo(block);
+                Quantization.ScaleSpectrum(block);
+                BandExtension.ApplyBandExtension(block);
+                ImdctBlock(block);
+            }
+        }
+
+        private static void ImdctBlock(Block block)
+        {
+            foreach (Channel channel in block.Channels)
+            {
+                channel.Mdct.RunImdct(channel.Spectra, channel.Pcm);
+            }
+        }
+    }
+}