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https://github.com/par274/sharpemu.git
synced 2026-07-31 06:59:45 +08:00
[audio] added sdl audio backend and in-tree atrac9 decoder
This commit is contained in:
ParantezTech
@@ -0,0 +1,427 @@
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// SPDX-License-Identifier: MIT
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#nullable disable
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using System;
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using System.IO;
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using LibAtrac9.Utilities;
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namespace LibAtrac9
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{
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internal static class Unpack
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{
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public static void UnpackFrame(BitReader reader, Frame frame)
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{
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foreach (Block block in frame.Blocks)
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{
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UnpackBlock(reader, block);
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}
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}
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private static void UnpackBlock(BitReader reader, Block block)
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{
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ReadBlockHeader(reader, block);
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if (block.BlockType == BlockType.LFE)
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{
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UnpackLfeBlock(reader, block);
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}
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else
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{
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UnpackStandardBlock(reader, block);
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}
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reader.AlignPosition(8);
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}
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private static void ReadBlockHeader(BitReader reader, Block block)
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{
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bool firstInSuperframe = block.Frame.FrameIndex == 0;
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block.FirstInSuperframe = !reader.ReadBool();
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block.ReuseBandParams = reader.ReadBool();
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if (block.FirstInSuperframe != firstInSuperframe)
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{
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throw new InvalidDataException();
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}
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if (firstInSuperframe && block.ReuseBandParams && block.BlockType != BlockType.LFE)
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{
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throw new InvalidDataException();
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}
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}
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private static void UnpackStandardBlock(BitReader reader, Block block)
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{
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Channel[] channels = block.Channels;
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if (!block.ReuseBandParams)
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{
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ReadBandParams(reader, block);
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}
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ReadGradientParams(reader, block);
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BitAllocation.CreateGradient(block);
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ReadStereoParams(reader, block);
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ReadExtensionParams(reader, block);
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foreach (Channel channel in channels)
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{
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channel.UpdateCodedUnits();
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ScaleFactors.Read(reader, channel);
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BitAllocation.CalculateMask(channel);
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BitAllocation.CalculatePrecisions(channel);
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CalculateSpectrumCodebookIndex(channel);
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ReadSpectra(reader, channel);
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ReadSpectraFine(reader, channel);
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}
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block.QuantizationUnitsPrev = block.BandExtensionEnabled ? block.ExtensionUnit : block.QuantizationUnitCount;
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}
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private static void ReadBandParams(BitReader reader, Block block)
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{
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int minBandCount = Tables.MinBandCount(block.Config.HighSampleRate);
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int maxExtensionBand = Tables.MaxExtensionBand(block.Config.HighSampleRate);
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block.BandCount = reader.ReadInt(4);
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block.BandCount += minBandCount;
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block.QuantizationUnitCount = Tables.BandToQuantUnitCount[block.BandCount];
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if (block.BandCount < minBandCount || block.BandCount >
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Tables.MaxBandCount[block.Config.SampleRateIndex])
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{
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return;
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}
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if (block.BlockType == BlockType.Stereo)
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{
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block.StereoBand = reader.ReadInt(4);
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block.StereoBand += minBandCount;
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block.StereoQuantizationUnit = Tables.BandToQuantUnitCount[block.StereoBand];
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}
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else
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{
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block.StereoBand = block.BandCount;
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}
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block.BandExtensionEnabled = reader.ReadBool();
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if (block.BandExtensionEnabled)
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{
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block.ExtensionBand = reader.ReadInt(4);
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block.ExtensionBand += minBandCount;
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if (block.ExtensionBand < block.BandCount || block.ExtensionBand > maxExtensionBand)
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{
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throw new InvalidDataException();
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}
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block.ExtensionUnit = Tables.BandToQuantUnitCount[block.ExtensionBand];
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}
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else
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{
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block.ExtensionBand = block.BandCount;
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block.ExtensionUnit = block.QuantizationUnitCount;
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}
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}
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private static void ReadGradientParams(BitReader reader, Block block)
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{
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block.GradientMode = reader.ReadInt(2);
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if (block.GradientMode > 0)
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{
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block.GradientEndUnit = 31;
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block.GradientEndValue = 31;
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block.GradientStartUnit = reader.ReadInt(5);
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block.GradientStartValue = reader.ReadInt(5);
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}
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else
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{
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block.GradientStartUnit = reader.ReadInt(6);
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block.GradientEndUnit = reader.ReadInt(6) + 1;
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block.GradientStartValue = reader.ReadInt(5);
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block.GradientEndValue = reader.ReadInt(5);
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}
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block.GradientBoundary = reader.ReadInt(4);
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if (block.GradientBoundary > block.QuantizationUnitCount)
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{
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throw new InvalidDataException();
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}
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if (block.GradientStartUnit < 1 || block.GradientStartUnit >= 48)
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{
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throw new InvalidDataException();
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}
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if (block.GradientEndUnit < 1 || block.GradientEndUnit >= 48)
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{
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throw new InvalidDataException();
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}
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if (block.GradientStartUnit > block.GradientEndUnit)
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{
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throw new InvalidDataException();
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}
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if (block.GradientStartValue < 0 || block.GradientStartValue >= 32)
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{
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throw new InvalidDataException();
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}
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if (block.GradientEndValue < 0 || block.GradientEndValue >= 32)
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{
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throw new InvalidDataException();
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}
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}
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private static void ReadStereoParams(BitReader reader, Block block)
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{
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if (block.BlockType != BlockType.Stereo) return;
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block.PrimaryChannelIndex = reader.ReadInt(1);
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block.HasJointStereoSigns = reader.ReadBool();
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if (block.HasJointStereoSigns)
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{
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for (int i = block.StereoQuantizationUnit; i < block.QuantizationUnitCount; i++)
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{
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block.JointStereoSigns[i] = reader.ReadInt(1);
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}
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}
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else
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{
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Array.Clear(block.JointStereoSigns, 0, block.JointStereoSigns.Length);
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}
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}
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private static void ReadExtensionParams(BitReader reader, Block block)
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{
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// ReSharper disable once RedundantAssignment
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int bexBand = 0;
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if (block.BandExtensionEnabled)
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{
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BandExtension.GetBexBandInfo(out bexBand, out _, out _, block.QuantizationUnitCount);
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if (block.BlockType == BlockType.Stereo)
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{
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ReadHeader(block.Channels[1]);
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}
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else
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{
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reader.Position += 1;
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}
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}
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block.HasExtensionData = reader.ReadBool();
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if (!block.HasExtensionData) return;
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if (!block.BandExtensionEnabled)
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{
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block.BexMode = reader.ReadInt(2);
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block.BexDataLength = reader.ReadInt(5);
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reader.Position += block.BexDataLength;
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return;
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}
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ReadHeader(block.Channels[0]);
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block.BexDataLength = reader.ReadInt(5);
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if (block.BexDataLength <= 0) return;
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int bexDataEnd = reader.Position + block.BexDataLength;
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ReadData(block.Channels[0]);
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if (block.BlockType == BlockType.Stereo)
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{
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ReadData(block.Channels[1]);
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}
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// Make sure we didn't read too many bits
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if (reader.Position > bexDataEnd)
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{
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throw new InvalidDataException();
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}
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void ReadHeader(Channel channel)
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{
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int bexMode = reader.ReadInt(2);
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channel.BexMode = bexBand > 2 ? bexMode : 4;
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channel.BexValueCount = BandExtension.BexEncodedValueCounts[channel.BexMode][bexBand];
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}
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void ReadData(Channel channel)
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{
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for (int i = 0; i < channel.BexValueCount; i++)
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{
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int dataLength = BandExtension.BexDataLengths[channel.BexMode][bexBand][i];
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channel.BexValues[i] = reader.ReadInt(dataLength);
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}
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}
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}
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private static void CalculateSpectrumCodebookIndex(Channel channel)
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{
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Array.Clear(channel.CodebookSet, 0, channel.CodebookSet.Length);
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int quantUnits = channel.CodedQuantUnits;
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int[] sf = channel.ScaleFactors;
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if (quantUnits <= 1) return;
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if (channel.Config.HighSampleRate) return;
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// Temporarily setting this value allows for simpler code by
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// making the last value a non-special case.
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int originalScaleTmp = sf[quantUnits];
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sf[quantUnits] = sf[quantUnits - 1];
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int avg = 0;
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if (quantUnits > 12)
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{
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for (int i = 0; i < 12; i++)
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{
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avg += sf[i];
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}
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avg = (avg + 6) / 12;
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}
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for (int i = 8; i < quantUnits; i++)
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{
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int prevSf = sf[i - 1];
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int nextSf = sf[i + 1];
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int minSf = Math.Min(prevSf, nextSf);
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if (sf[i] - minSf >= 3 || sf[i] - prevSf + sf[i] - nextSf >= 3)
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{
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channel.CodebookSet[i] = 1;
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}
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}
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for (int i = 12; i < quantUnits; i++)
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{
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if (channel.CodebookSet[i] == 0)
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{
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int minSf = Math.Min(sf[i - 1], sf[i + 1]);
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if (sf[i] - minSf >= 2 && sf[i] >= avg - (Tables.QuantUnitToCoeffCount[i] == 16 ? 1 : 0))
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{
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channel.CodebookSet[i] = 1;
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}
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}
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}
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sf[quantUnits] = originalScaleTmp;
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}
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private static void ReadSpectra(BitReader reader, Channel channel)
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{
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int[] values = channel.SpectraValuesBuffer;
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Array.Clear(channel.QuantizedSpectra, 0, channel.QuantizedSpectra.Length);
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int maxHuffPrecision = Tables.MaxHuffPrecision(channel.Config.HighSampleRate);
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for (int i = 0; i < channel.CodedQuantUnits; i++)
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{
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int subbandCount = Tables.QuantUnitToCoeffCount[i];
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int precision = channel.Precisions[i] + 1;
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if (precision <= maxHuffPrecision)
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{
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HuffmanCodebook huff = Tables.HuffmanSpectrum[channel.CodebookSet[i]][precision][Tables.QuantUnitToCodebookIndex[i]];
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int groupCount = subbandCount >> huff.ValueCountPower;
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for (int j = 0; j < groupCount; j++)
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{
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values[j] = ReadHuffmanValue(huff, reader);
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}
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DecodeHuffmanValues(channel.QuantizedSpectra, Tables.QuantUnitToCoeffIndex[i], subbandCount, huff, values);
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}
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else
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{
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int subbandIndex = Tables.QuantUnitToCoeffIndex[i];
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for (int j = subbandIndex; j < Tables.QuantUnitToCoeffIndex[i + 1]; j++)
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{
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channel.QuantizedSpectra[j] = reader.ReadSignedInt(precision);
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}
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}
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}
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}
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private static void ReadSpectraFine(BitReader reader, Channel channel)
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{
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Array.Clear(channel.QuantizedSpectraFine, 0, channel.QuantizedSpectraFine.Length);
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for (int i = 0; i < channel.CodedQuantUnits; i++)
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{
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if (channel.PrecisionsFine[i] > 0)
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{
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int overflowBits = channel.PrecisionsFine[i] + 1;
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int startSubband = Tables.QuantUnitToCoeffIndex[i];
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int endSubband = Tables.QuantUnitToCoeffIndex[i + 1];
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for (int j = startSubband; j < endSubband; j++)
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{
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channel.QuantizedSpectraFine[j] = reader.ReadSignedInt(overflowBits);
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}
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}
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}
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}
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private static void DecodeHuffmanValues(int[] spectrum, int index, int bandCount, HuffmanCodebook huff, int[] values)
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{
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int valueCount = bandCount >> huff.ValueCountPower;
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int mask = (1 << huff.ValueBits) - 1;
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for (int i = 0; i < valueCount; i++)
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{
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int value = values[i];
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for (int j = 0; j < huff.ValueCount; j++)
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{
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spectrum[index++] = Bit.SignExtend32(value & mask, huff.ValueBits);
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value >>= huff.ValueBits;
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}
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}
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}
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public static int ReadHuffmanValue(HuffmanCodebook huff, BitReader reader, bool signed = false)
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{
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int code = reader.PeekInt(huff.MaxBitSize);
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byte value = huff.Lookup[code];
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int bits = huff.Bits[value];
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reader.Position += bits;
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return signed ? Bit.SignExtend32(value, huff.ValueBits) : value;
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}
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private static void UnpackLfeBlock(BitReader reader, Block block)
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{
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Channel channel = block.Channels[0];
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block.QuantizationUnitCount = 2;
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DecodeLfeScaleFactors(reader, channel);
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CalculateLfePrecision(channel);
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channel.CodedQuantUnits = block.QuantizationUnitCount;
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ReadLfeSpectra(reader, channel);
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}
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private static void DecodeLfeScaleFactors(BitReader reader, Channel channel)
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{
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Array.Clear(channel.ScaleFactors, 0, channel.ScaleFactors.Length);
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for (int i = 0; i < channel.Block.QuantizationUnitCount; i++)
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{
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channel.ScaleFactors[i] = reader.ReadInt(5);
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}
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}
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private static void CalculateLfePrecision(Channel channel)
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{
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Block block = channel.Block;
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int precision = block.ReuseBandParams ? 8 : 4;
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for (int i = 0; i < block.QuantizationUnitCount; i++)
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{
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channel.Precisions[i] = precision;
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channel.PrecisionsFine[i] = 0;
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}
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}
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private static void ReadLfeSpectra(BitReader reader, Channel channel)
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{
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Array.Clear(channel.QuantizedSpectra, 0, channel.QuantizedSpectra.Length);
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for (int i = 0; i < channel.CodedQuantUnits; i++)
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{
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if (channel.Precisions[i] <= 0) continue;
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int precision = channel.Precisions[i] + 1;
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for (int j = Tables.QuantUnitToCoeffIndex[i]; j < Tables.QuantUnitToCoeffIndex[i + 1]; j++)
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{
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channel.QuantizedSpectra[j] = reader.ReadSignedInt(precision);
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}
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}
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}
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}
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}
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Reference in New Issue
Block a user