OniSplit/Sound/WavExporter.cs

using System;
using System.IO;

namespace Oni.Sound
{
    internal class WavExporter : SoundExporter
    {
        #region Private data
        private bool convert_to_PCM;

        private const int fcc_RIFF = 0x46464952;
        private const int fcc_WAVE = 0x45564157;
        private const int fcc_fmt = 0x20746d66;
        private const int fcc_fact = 0x74636166;
        private const int fcc_data = 0x61746164;

        private static readonly byte[] formatTemplate_ADPCM = new byte[50]
        {
            0x02, 0,    // format ID (2 for ADPCM)
            0, 0,       // ChannelCount (overwritten)
            0x22, 0x56, 0, 0, // SampleRate (usually 22050, can be 44100)
            0, 0, 0, 0, // average data rate (computed and overwritten)
            0, 0x02,    // block alignment (default 512, can be 1024)
            0x04, 0,    // bits per sample (always 4)
            0x20, 0,    // size of extended ADPCM header block
            0xf4, 0x03, // samples per block (usually 1012, can be 2036)
            0x07, 0,    // standard ADPCM coefficient table (always the same)
            0, 0x01, 0, 0,
            0, 0x02, 0, 0xff,
            0, 0, 0, 0,
            0xc0, 0, 0x40, 0,
            0xf0, 0, 0, 0,
            0xcc, 0x01, 0x30, 0xff,
            0x88, 0x01, 0x18, 0xff
        };

        private static readonly byte[] formatTemplate_PCM = new byte[16]
        {
            0x01, 0,    // format ID (1 for linear PCM)
            0, 0,       // ChannelCount (overwritten)
            0x22, 0x56, 0, 0, // SampleRate (usually 22050, can be 44100)
            0, 0, 0, 0, // data rate in bytes/s (computed and overwritten)
            0x02, 0,    // block size (2 bytes for mono, 4 for stereo)
            0x10, 0     // bits per sample (always 16)
        };

        private static readonly byte[] factTemplate = new byte[4]
        {
            0, 0, 0, 0  // sample count (computed and overwritten)
        };

        private static readonly int[] ima_index_table = new int[16]
        {
           -1, -1, -1, -1, 2, 4, 6, 8,
           -1, -1, -1, -1, 2, 4, 6, 8
        };

        private static readonly int[] ima_step_table = new int[89]
        {
            7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
            19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
            50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
            130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
            337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
            876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
            2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
            5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
            15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
        };

        private static readonly int[] msadpcm_adapt_table = new int[16]
        {
            230, 230, 230, 230, 307, 409, 512, 614,
            768, 614, 512, 409, 307, 230, 230, 230
        };

        private static readonly int[] msadpcm_coeff_table1 = new int[7]
        {
            256, 512, 0, 192, 240, 460, 392
        };

        private static readonly int[] msadpcm_coeff_table2 = new int[7]
        {
            0, -256, 0, 64, 0, -208, -232
        };
        #endregion

        public WavExporter(InstanceFileManager fileManager, string outputDirPath, bool convertToPCM = false)
            : base(fileManager, outputDirPath)
        {
            convert_to_PCM = convertToPCM;
        }

        private static void ClampToRange(ref int value, int lower, int upper)
        {
            if (value > upper)
                value = upper;
            if (value < lower)
                value = lower;
        }

        protected Int16 NibbletoSampleIMA4(ref int predictor, ref int step_index, Byte nibble)
        {
            int step = ima_step_table[step_index];

            step_index += ima_index_table[nibble];
            ClampToRange(ref step_index, 0, 88);

            int diff = step >> 3;

            if ((nibble & 0x04) != 0) diff +=  step;
            if ((nibble & 0x02) != 0) diff += (step >> 1);
            if ((nibble & 0x01) != 0) diff += (step >> 2);
            if ((nibble & 0x08) != 0)
                predictor -= diff;
            else
                predictor += diff;

            ClampToRange(ref predictor, -32768, 32767);
            return (Int16)predictor;
        }

        protected Int16 NibbletoSampleMSADPCM(ref Int16 sample1, ref Int16 sample2, ref UInt16 delta, Byte pred_index, Byte nibble)
        {
            int coeff1 = msadpcm_coeff_table1[pred_index];
            int coeff2 = msadpcm_coeff_table2[pred_index];

            int prediction = ((int)sample1 * (int)coeff1 + (int)sample2 * (int)coeff2) >> 8;

            int snibble = (nibble < 8) ? nibble : (nibble - 16);
            int correction = snibble * (int)delta;

            int sample = prediction + correction;
            ClampToRange(ref sample, -32768, 32767);

            sample2 = sample1;
            sample1 = (Int16)sample;

            int newDelta = delta * msadpcm_adapt_table[nibble];
            newDelta >>= 8;
            ClampToRange(ref newDelta, 16, 65535);
            delta = (UInt16)newDelta;

            return (Int16)sample;
        }

        protected override void ExportInstance(InstanceDescriptor descriptor)
        {
            var sound = SoundData.Read(descriptor);

            using (var stream = File.Create(Path.Combine(OutputDirPath, descriptor.FullName + ".wav")))
            using (var writer = new BinaryWriter(stream))
            {
                var blockSizeADPCM = 512 * sound.ChannelCount * sound.SampleRate / 22050;
                int wholeBlocks = sound.Data.Length / blockSizeADPCM;
                int leftoverBytes = sound.Data.Length - (wholeBlocks * blockSizeADPCM);
                int leftoverSamples = 8 * (leftoverBytes - 7 * sound.ChannelCount)
                                      / 4 / sound.ChannelCount + 2; // 4 bits per sample
                int paddingBytes = 0;
                if (leftoverBytes > 0) // incomplete trailing block
                    paddingBytes = blockSizeADPCM - leftoverBytes;
                var samplesPerBlock = 2 + (blockSizeADPCM - sound.ChannelCount * 7) * 8 / sound.ChannelCount / 4;

                Int32 sampleCount = sampleCount = wholeBlocks * samplesPerBlock + leftoverSamples; 
                
                if (sound.IsIMA4) // IMA4 ADPCM format
                {
                    blockSizeADPCM = 34 * sound.ChannelCount;
                    samplesPerBlock = 64;
                    sampleCount = (sound.Data.Length / blockSizeADPCM) * samplesPerBlock;
                }

                if (!convert_to_PCM)
                {
                    if (sound.IsIMA4)
                    {
                        throw new NotSupportedException("Transcoding from Mac/demo ADPCM to PC ADPCM not supported! Please use -extract:pcm");
                    }
                    var format = (byte[])formatTemplate_ADPCM.Clone();
                    var fact = (byte[])factTemplate.Clone(); // needed for ADPCM (to specify the actual sample count)

                    var averageRate = sound.SampleRate * blockSizeADPCM / samplesPerBlock;
                    Array.Copy(BitConverter.GetBytes(sound.ChannelCount), 0, format, 2, 2);
                    Array.Copy(BitConverter.GetBytes(sound.SampleRate), 0, format, 4, 4);
                    Array.Copy(BitConverter.GetBytes(averageRate), 0, format, 8, 4);
                    Array.Copy(BitConverter.GetBytes(blockSizeADPCM), 0, format, 12, 2);
                    Array.Copy(BitConverter.GetBytes(samplesPerBlock), 0, format, 18, 2);

                    Array.Copy(BitConverter.GetBytes(sampleCount), 0, fact, 0, 4);

                    writer.Write(fcc_RIFF);
                    writer.Write(8 + format.Length + 8 + fact.Length + 8 + sound.Data.Length + paddingBytes);
                    writer.Write(fcc_WAVE);

                    //
                    // write format chunk
                    //
                    writer.Write(fcc_fmt);
                    writer.Write(format.Length);
                    writer.Write(format);

                    //
                    // write fact chunk
                    //
                    writer.Write(fcc_fact);
                    writer.Write(fact.Length);
                    writer.Write(fact);

                    //
                    // write data chunk
                    //
                    writer.Write(fcc_data);
                    writer.Write(sound.Data.Length + paddingBytes);
                    writer.Write(sound.Data);

                    Byte c = 0;
                    for (int i = 0; i < paddingBytes; i++)
                        writer.Write(c);
                }
                else
                {
                    var format = (byte[])formatTemplate_PCM.Clone();

                    var blockSizePCM = 2 * sound.ChannelCount; // 16-bit samples or sample pairs
                    samplesPerBlock = 2;
                    var averageRate = sound.SampleRate * blockSizePCM / samplesPerBlock;
                    Array.Copy(BitConverter.GetBytes(sound.ChannelCount), 0, format, 2, 2);
                    Array.Copy(BitConverter.GetBytes(sound.SampleRate), 0, format, 4, 4);
                    Array.Copy(BitConverter.GetBytes(averageRate), 0, format, 8, 4);
                    Array.Copy(BitConverter.GetBytes(blockSizePCM), 0, format, 12, 2);

                    int dataSize = blockSizePCM * sampleCount;

                    writer.Write(fcc_RIFF);
                    writer.Write(8 + format.Length + 8 + dataSize);
                    writer.Write(fcc_WAVE);

                    //
                    // write format chunk
                    //

                    writer.Write(fcc_fmt);
                    writer.Write(format.Length);
                    writer.Write(format);

                    //
                    // write data chunk
                    //
                    var samplesL = new Int16[sampleCount];
                    var samplesR = new Int16[sampleCount];
                    if (sound.IsIMA4) // decode IMA4 into linear signed 16-bit PCM
                    {
                        int pos = 0;

                        int iSampleL = 0;
                        int predictorL = 0;
                        int stepIndexL = 0;
                        int iSampleR = 0;
                        int predictorR = 0;
                        int stepIndexR = 0;

                        int nBlocks = sound.Data.Length / blockSizeADPCM;
                        for (int block = 0; block < nBlocks; block++)
                        {
                            byte headerHiL = sound.Data[pos++];
                            byte headerLoL = sound.Data[pos++];
                            if (block == 0) // non-standard decoding: predictor initialization ignored after start
                            {
                                predictorL = ((((headerHiL << 1) | (headerLoL >> 7))) << 7);
                                if (predictorL > 32767) predictorL -= 65536;
                            }
                            stepIndexL = headerLoL & 0x7f;
                            for (int b = 0; b < 32; b++)
                            {
                                Byte nibblesL = sound.Data[pos++];
                                Byte nibbleHiL = (Byte)(nibblesL >> 4);
                                Byte nibbleLoL = (Byte)(nibblesL & 0xF);

                                samplesL[iSampleL++] = NibbletoSampleIMA4(ref predictorL, ref stepIndexL, nibbleLoL);
                                samplesL[iSampleL++] = NibbletoSampleIMA4(ref predictorL, ref stepIndexL, nibbleHiL);
                            }

                            if (sound.ChannelCount == 2)
                            {
                                byte headerHiR = sound.Data[pos++];
                                byte headerLoR = sound.Data[pos++];
                                if (block == 0) // non-standard decoding: predictor initialization ignored after start
                                {
                                    predictorR = ((((headerHiR << 1) | (headerLoR >> 7))) << 7);
                                    if (predictorR > 32767) predictorR -= 65536;
                                }
                                stepIndexR = headerLoR & 0x7f;

                                for (int b = 0; b < 32; b++)
                                {
                                    Byte nibblesR = sound.Data[pos++];
                                    Byte nibbleHiR = (Byte)(nibblesR >> 4);
                                    Byte nibbleLoR = (Byte)(nibblesR & 0xF);

                                    samplesR[iSampleR++] = NibbletoSampleIMA4(ref predictorR, ref stepIndexR, nibbleLoR);
                                    samplesR[iSampleR++] = NibbletoSampleIMA4(ref predictorR, ref stepIndexR, nibbleHiR);
                                }
                            }
                        }
                    }
                    else // decode MSADPCM into linear signed 16-bit PCM
                    {
                        int pos = 0;
                        Byte pred_indexL = 0, pred_indexR = 0;
                        UInt16 deltaL = 0, deltaR = 0;
                        int iSampleL = 0;
                        int iSampleR = 0;
                        Int16 sample1L = 0, sample2L = 0;
                        Int16 sample1R = 0, sample2R = 0;

                        while (pos < sound.Data.Length)
                        {
                            if ((pos % blockSizeADPCM) == 0) // read block header
                            {
                                pred_indexL = sound.Data[pos++];
                                if (sound.ChannelCount == 2)
                                    pred_indexR = sound.Data[pos++];
                                Byte deltaLo = sound.Data[pos++];
                                Byte deltaHi = sound.Data[pos++];
                                deltaL = (UInt16)(deltaLo + 256 * deltaHi);
                                if (sound.ChannelCount == 2)
                                {
                                    deltaLo = sound.Data[pos++];
                                    deltaHi = sound.Data[pos++];
                                    deltaR = (UInt16)(deltaLo + 256 * deltaHi);
                                }
                                Byte sampleLo = sound.Data[pos++];
                                Byte sampleHi = sound.Data[pos++];
                                UInt16 usample = (UInt16)(sampleLo + 256 * sampleHi);
                                sample1L = (Int16)((usample < 32767) ? usample : (usample - 65536));
                                if (sound.ChannelCount == 2)
                                {
                                    sampleLo = sound.Data[pos++];
                                    sampleHi = sound.Data[pos++];
                                    usample = (UInt16)(sampleLo + 256 * sampleHi);
                                    sample1R = (Int16)((usample < 32767) ? usample : (usample - 65536));
                                }
                                sampleLo = sound.Data[pos++];
                                sampleHi = sound.Data[pos++];
                                usample = (UInt16)(sampleLo + 256 * sampleHi);
                                sample2L = (Int16)((usample < 32767) ? usample : (usample - 65536));
                                if (sound.ChannelCount == 2)
                                {
                                    sampleLo = sound.Data[pos++];
                                    sampleHi = sound.Data[pos++];
                                    usample = (UInt16)(sampleLo + 256 * sampleHi);
                                    sample2R = (Int16)((usample < 32767) ? usample : (usample - 65536));
                                }
                                samplesL[iSampleL++] = sample2L;
                                samplesL[iSampleL++] = sample1L;
                                if (sound.ChannelCount == 2)
                                {
                                    samplesR[iSampleR++] = sample2R;
                                    samplesR[iSampleR++] = sample1R;
                                }
                            }
                            // read pair of nibbles
                            Byte nibbles = sound.Data[pos++];
                            Byte nibbleHi = (Byte)(nibbles >> 4);
                            Byte nibbleLo = (Byte)(nibbles & 0xF);
                            samplesL[iSampleL++] = NibbletoSampleMSADPCM(ref sample1L, ref sample2L, ref deltaL, pred_indexL, nibbleHi);
                            if (sound.ChannelCount == 2)
                                samplesR[iSampleR++] = NibbletoSampleMSADPCM(ref sample1R, ref sample2R, ref deltaR, pred_indexR, nibbleLo);
                            else
                                samplesL[iSampleL++] = NibbletoSampleMSADPCM(ref sample1L, ref sample2L, ref deltaL, pred_indexL, nibbleLo);
                        }
                    }
                    writer.Write(fcc_data);
                    writer.Write(dataSize);
                    for (int smp = 0; smp < sampleCount; smp++)
                    {
                        writer.Write(samplesL[smp]);
                        if(sound.ChannelCount == 2)
                            writer.Write(samplesR[smp]);
                    }
                }
            }
        }
    }
}
Revision:	1130
Committed:	Thu May 28 21:28:44 2020 UTC (5 years, 4 months ago) by geyser
File size:	18108 byte(s)
Log Message:	Minor fixes and features in SNDD export: "transcoding" forbidden, standard-compliant MSADPCM (with padding and "fact" section), PCM export (with -extract:pcm).
#	Content
1	using System;
2	using System.IO;
3
4	namespace Oni.Sound
5	{
6	internal class WavExporter : SoundExporter
7	{
8	#region Private data
9	private bool convert_to_PCM;
10
11	private const int fcc_RIFF = 0x46464952;
12	private const int fcc_WAVE = 0x45564157;
13	private const int fcc_fmt = 0x20746d66;
14	private const int fcc_fact = 0x74636166;
15	private const int fcc_data = 0x61746164;
16
17	private static readonly byte[] formatTemplate_ADPCM = new byte[50]
18	{
19	0x02, 0, // format ID (2 for ADPCM)
20	0, 0, // ChannelCount (overwritten)
21	0x22, 0x56, 0, 0, // SampleRate (usually 22050, can be 44100)
22	0, 0, 0, 0, // average data rate (computed and overwritten)
23	0, 0x02, // block alignment (default 512, can be 1024)
24	0x04, 0, // bits per sample (always 4)
25	0x20, 0, // size of extended ADPCM header block
26	0xf4, 0x03, // samples per block (usually 1012, can be 2036)
27	0x07, 0, // standard ADPCM coefficient table (always the same)
28	0, 0x01, 0, 0,
29	0, 0x02, 0, 0xff,
30	0, 0, 0, 0,
31	0xc0, 0, 0x40, 0,
32	0xf0, 0, 0, 0,
33	0xcc, 0x01, 0x30, 0xff,
34	0x88, 0x01, 0x18, 0xff
35	};
36
37	private static readonly byte[] formatTemplate_PCM = new byte[16]
38	{
39	0x01, 0, // format ID (1 for linear PCM)
40	0, 0, // ChannelCount (overwritten)
41	0x22, 0x56, 0, 0, // SampleRate (usually 22050, can be 44100)
42	0, 0, 0, 0, // data rate in bytes/s (computed and overwritten)
43	0x02, 0, // block size (2 bytes for mono, 4 for stereo)
44	0x10, 0 // bits per sample (always 16)
45	};
46
47	private static readonly byte[] factTemplate = new byte[4]
48	{
49	0, 0, 0, 0 // sample count (computed and overwritten)
50	};
51
52	private static readonly int[] ima_index_table = new int[16]
53	{
54	-1, -1, -1, -1, 2, 4, 6, 8,
55	-1, -1, -1, -1, 2, 4, 6, 8
56	};
57
58	private static readonly int[] ima_step_table = new int[89]
59	{
60	7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
61	19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
62	50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
63	130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
64	337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
65	876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
66	2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
67	5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
68	15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
69	};
70
71	private static readonly int[] msadpcm_adapt_table = new int[16]
72	{
73	230, 230, 230, 230, 307, 409, 512, 614,
74	768, 614, 512, 409, 307, 230, 230, 230
75	};
76
77	private static readonly int[] msadpcm_coeff_table1 = new int[7]
78	{
79	256, 512, 0, 192, 240, 460, 392
80	};
81
82	private static readonly int[] msadpcm_coeff_table2 = new int[7]
83	{
84	0, -256, 0, 64, 0, -208, -232
85	};
86	#endregion
87
88	public WavExporter(InstanceFileManager fileManager, string outputDirPath, bool convertToPCM = false)
89	: base(fileManager, outputDirPath)
90	{
91	convert_to_PCM = convertToPCM;
92	}
93
94	private static void ClampToRange(ref int value, int lower, int upper)
95	{
96	if (value > upper)
97	value = upper;
98	if (value < lower)
99	value = lower;
100	}
101
102	protected Int16 NibbletoSampleIMA4(ref int predictor, ref int step_index, Byte nibble)
103	{
104	int step = ima_step_table[step_index];
105
106	step_index += ima_index_table[nibble];
107	ClampToRange(ref step_index, 0, 88);
108
109	int diff = step >> 3;
110
111	if ((nibble & 0x04) != 0) diff += step;
112	if ((nibble & 0x02) != 0) diff += (step >> 1);
113	if ((nibble & 0x01) != 0) diff += (step >> 2);
114	if ((nibble & 0x08) != 0)
115	predictor -= diff;
116	else
117	predictor += diff;
118
119	ClampToRange(ref predictor, -32768, 32767);
120	return (Int16)predictor;
121	}
122
123	protected Int16 NibbletoSampleMSADPCM(ref Int16 sample1, ref Int16 sample2, ref UInt16 delta, Byte pred_index, Byte nibble)
124	{
125	int coeff1 = msadpcm_coeff_table1[pred_index];
126	int coeff2 = msadpcm_coeff_table2[pred_index];
127
128	int prediction = ((int)sample1 * (int)coeff1 + (int)sample2 * (int)coeff2) >> 8;
129
130	int snibble = (nibble < 8) ? nibble : (nibble - 16);
131	int correction = snibble * (int)delta;
132
133	int sample = prediction + correction;
134	ClampToRange(ref sample, -32768, 32767);
135
136	sample2 = sample1;
137	sample1 = (Int16)sample;
138
139	int newDelta = delta * msadpcm_adapt_table[nibble];
140	newDelta >>= 8;
141	ClampToRange(ref newDelta, 16, 65535);
142	delta = (UInt16)newDelta;
143
144	return (Int16)sample;
145	}
146
147	protected override void ExportInstance(InstanceDescriptor descriptor)
148	{
149	var sound = SoundData.Read(descriptor);
150
151	using (var stream = File.Create(Path.Combine(OutputDirPath, descriptor.FullName + ".wav")))
152	using (var writer = new BinaryWriter(stream))
153	{
154	var blockSizeADPCM = 512 * sound.ChannelCount * sound.SampleRate / 22050;
155	int wholeBlocks = sound.Data.Length / blockSizeADPCM;
156	int leftoverBytes = sound.Data.Length - (wholeBlocks * blockSizeADPCM);
157	int leftoverSamples = 8 * (leftoverBytes - 7 * sound.ChannelCount)
158	/ 4 / sound.ChannelCount + 2; // 4 bits per sample
159	int paddingBytes = 0;
160	if (leftoverBytes > 0) // incomplete trailing block
161	paddingBytes = blockSizeADPCM - leftoverBytes;
162	var samplesPerBlock = 2 + (blockSizeADPCM - sound.ChannelCount * 7) * 8 / sound.ChannelCount / 4;
163
164	Int32 sampleCount = sampleCount = wholeBlocks * samplesPerBlock + leftoverSamples;
165
166	if (sound.IsIMA4) // IMA4 ADPCM format
167	{
168	blockSizeADPCM = 34 * sound.ChannelCount;
169	samplesPerBlock = 64;
170	sampleCount = (sound.Data.Length / blockSizeADPCM) * samplesPerBlock;
171	}
172
173	if (!convert_to_PCM)
174	{
175	if (sound.IsIMA4)
176	{
177	throw new NotSupportedException("Transcoding from Mac/demo ADPCM to PC ADPCM not supported! Please use -extract:pcm");
178	}
179	var format = (byte[])formatTemplate_ADPCM.Clone();
180	var fact = (byte[])factTemplate.Clone(); // needed for ADPCM (to specify the actual sample count)
181
182	var averageRate = sound.SampleRate * blockSizeADPCM / samplesPerBlock;
183	Array.Copy(BitConverter.GetBytes(sound.ChannelCount), 0, format, 2, 2);
184	Array.Copy(BitConverter.GetBytes(sound.SampleRate), 0, format, 4, 4);
185	Array.Copy(BitConverter.GetBytes(averageRate), 0, format, 8, 4);
186	Array.Copy(BitConverter.GetBytes(blockSizeADPCM), 0, format, 12, 2);
187	Array.Copy(BitConverter.GetBytes(samplesPerBlock), 0, format, 18, 2);
188
189	Array.Copy(BitConverter.GetBytes(sampleCount), 0, fact, 0, 4);
190
191	writer.Write(fcc_RIFF);
192	writer.Write(8 + format.Length + 8 + fact.Length + 8 + sound.Data.Length + paddingBytes);
193	writer.Write(fcc_WAVE);
194
195	//
196	// write format chunk
197	//
198	writer.Write(fcc_fmt);
199	writer.Write(format.Length);
200	writer.Write(format);
201
202	//
203	// write fact chunk
204	//
205	writer.Write(fcc_fact);
206	writer.Write(fact.Length);
207	writer.Write(fact);
208
209	//
210	// write data chunk
211	//
212	writer.Write(fcc_data);
213	writer.Write(sound.Data.Length + paddingBytes);
214	writer.Write(sound.Data);
215
216	Byte c = 0;
217	for (int i = 0; i < paddingBytes; i++)
218	writer.Write(c);
219	}
220	else
221	{
222	var format = (byte[])formatTemplate_PCM.Clone();
223
224	var blockSizePCM = 2 * sound.ChannelCount; // 16-bit samples or sample pairs
225	samplesPerBlock = 2;
226	var averageRate = sound.SampleRate * blockSizePCM / samplesPerBlock;
227	Array.Copy(BitConverter.GetBytes(sound.ChannelCount), 0, format, 2, 2);
228	Array.Copy(BitConverter.GetBytes(sound.SampleRate), 0, format, 4, 4);
229	Array.Copy(BitConverter.GetBytes(averageRate), 0, format, 8, 4);
230	Array.Copy(BitConverter.GetBytes(blockSizePCM), 0, format, 12, 2);
231
232	int dataSize = blockSizePCM * sampleCount;
233
234	writer.Write(fcc_RIFF);
235	writer.Write(8 + format.Length + 8 + dataSize);
236	writer.Write(fcc_WAVE);
237
238	//
239	// write format chunk
240	//
241
242	writer.Write(fcc_fmt);
243	writer.Write(format.Length);
244	writer.Write(format);
245
246	//
247	// write data chunk
248	//
249	var samplesL = new Int16[sampleCount];
250	var samplesR = new Int16[sampleCount];
251	if (sound.IsIMA4) // decode IMA4 into linear signed 16-bit PCM
252	{
253	int pos = 0;
254
255	int iSampleL = 0;
256	int predictorL = 0;
257	int stepIndexL = 0;
258	int iSampleR = 0;
259	int predictorR = 0;
260	int stepIndexR = 0;
261
262	int nBlocks = sound.Data.Length / blockSizeADPCM;
263	for (int block = 0; block < nBlocks; block++)
264	{
265	byte headerHiL = sound.Data[pos++];
266	byte headerLoL = sound.Data[pos++];
267	if (block == 0) // non-standard decoding: predictor initialization ignored after start
268	{
269	predictorL = ((((headerHiL << 1) \| (headerLoL >> 7))) << 7);
270	if (predictorL > 32767) predictorL -= 65536;
271	}
272	stepIndexL = headerLoL & 0x7f;
273	for (int b = 0; b < 32; b++)
274	{
275	Byte nibblesL = sound.Data[pos++];
276	Byte nibbleHiL = (Byte)(nibblesL >> 4);
277	Byte nibbleLoL = (Byte)(nibblesL & 0xF);
278
279	samplesL[iSampleL++] = NibbletoSampleIMA4(ref predictorL, ref stepIndexL, nibbleLoL);
280	samplesL[iSampleL++] = NibbletoSampleIMA4(ref predictorL, ref stepIndexL, nibbleHiL);
281	}
282
283	if (sound.ChannelCount == 2)
284	{
285	byte headerHiR = sound.Data[pos++];
286	byte headerLoR = sound.Data[pos++];
287	if (block == 0) // non-standard decoding: predictor initialization ignored after start
288	{
289	predictorR = ((((headerHiR << 1) \| (headerLoR >> 7))) << 7);
290	if (predictorR > 32767) predictorR -= 65536;
291	}
292	stepIndexR = headerLoR & 0x7f;
293
294	for (int b = 0; b < 32; b++)
295	{
296	Byte nibblesR = sound.Data[pos++];
297	Byte nibbleHiR = (Byte)(nibblesR >> 4);
298	Byte nibbleLoR = (Byte)(nibblesR & 0xF);
299
300	samplesR[iSampleR++] = NibbletoSampleIMA4(ref predictorR, ref stepIndexR, nibbleLoR);
301	samplesR[iSampleR++] = NibbletoSampleIMA4(ref predictorR, ref stepIndexR, nibbleHiR);
302	}
303	}
304	}
305	}
306	else // decode MSADPCM into linear signed 16-bit PCM
307	{
308	int pos = 0;
309	Byte pred_indexL = 0, pred_indexR = 0;
310	UInt16 deltaL = 0, deltaR = 0;
311	int iSampleL = 0;
312	int iSampleR = 0;
313	Int16 sample1L = 0, sample2L = 0;
314	Int16 sample1R = 0, sample2R = 0;
315
316	while (pos < sound.Data.Length)
317	{
318	if ((pos % blockSizeADPCM) == 0) // read block header
319	{
320	pred_indexL = sound.Data[pos++];
321	if (sound.ChannelCount == 2)
322	pred_indexR = sound.Data[pos++];
323	Byte deltaLo = sound.Data[pos++];
324	Byte deltaHi = sound.Data[pos++];
325	deltaL = (UInt16)(deltaLo + 256 * deltaHi);
326	if (sound.ChannelCount == 2)
327	{
328	deltaLo = sound.Data[pos++];
329	deltaHi = sound.Data[pos++];
330	deltaR = (UInt16)(deltaLo + 256 * deltaHi);
331	}
332	Byte sampleLo = sound.Data[pos++];
333	Byte sampleHi = sound.Data[pos++];
334	UInt16 usample = (UInt16)(sampleLo + 256 * sampleHi);
335	sample1L = (Int16)((usample < 32767) ? usample : (usample - 65536));
336	if (sound.ChannelCount == 2)
337	{
338	sampleLo = sound.Data[pos++];
339	sampleHi = sound.Data[pos++];
340	usample = (UInt16)(sampleLo + 256 * sampleHi);
341	sample1R = (Int16)((usample < 32767) ? usample : (usample - 65536));
342	}
343	sampleLo = sound.Data[pos++];
344	sampleHi = sound.Data[pos++];
345	usample = (UInt16)(sampleLo + 256 * sampleHi);
346	sample2L = (Int16)((usample < 32767) ? usample : (usample - 65536));
347	if (sound.ChannelCount == 2)
348	{
349	sampleLo = sound.Data[pos++];
350	sampleHi = sound.Data[pos++];
351	usample = (UInt16)(sampleLo + 256 * sampleHi);
352	sample2R = (Int16)((usample < 32767) ? usample : (usample - 65536));
353	}
354	samplesL[iSampleL++] = sample2L;
355	samplesL[iSampleL++] = sample1L;
356	if (sound.ChannelCount == 2)
357	{
358	samplesR[iSampleR++] = sample2R;
359	samplesR[iSampleR++] = sample1R;
360	}
361	}
362	// read pair of nibbles
363	Byte nibbles = sound.Data[pos++];
364	Byte nibbleHi = (Byte)(nibbles >> 4);
365	Byte nibbleLo = (Byte)(nibbles & 0xF);
366	samplesL[iSampleL++] = NibbletoSampleMSADPCM(ref sample1L, ref sample2L, ref deltaL, pred_indexL, nibbleHi);
367	if (sound.ChannelCount == 2)
368	samplesR[iSampleR++] = NibbletoSampleMSADPCM(ref sample1R, ref sample2R, ref deltaR, pred_indexR, nibbleLo);
369	else
370	samplesL[iSampleL++] = NibbletoSampleMSADPCM(ref sample1L, ref sample2L, ref deltaL, pred_indexL, nibbleLo);
371	}
372	}
373	writer.Write(fcc_data);
374	writer.Write(dataSize);
375	for (int smp = 0; smp < sampleCount; smp++)
376	{
377	writer.Write(samplesL[smp]);
378	if(sound.ChannelCount == 2)
379	writer.Write(samplesR[smp]);
380	}
381	}
382	}
383	}
384	}
385	}