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Merge branch 'p1-w1-wav-format-extensions' into dev

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daniel-c-harvey
2026-06-10 20:41:04 -04:00
parent 3953229ae4 8d80d43a47
commit 092ac0b5f2
2 changed files with 420 additions and 22 deletions
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DeepDrftContent/Processors/AudioProcessor.cs
+157 -22
View File
@@ -69,11 +69,23 @@ public class AudioProcessor
return null;
}
// Float and padded-container EXTENSIBLE require a sample-level transform to become integer PCM.
// TryExtractPcm feeds loudness analysis, not storage, and must not hand back float bytes
// mislabeled as integer PCM — out of scope here, so treat them as "no profile computable".
if (validation.IsFloat)
{
return null;
}
WavMetadata metadata;
try
{
metadata = ParseWavMetadata(bytes, validation);
ValidateAudioParameters(metadata);
if (metadata.IsPaddedContainer)
{
return null;
}
}
catch
{
@@ -162,10 +174,12 @@ public class AudioProcessor
}
// Validate audio format. Standard PCM (1) is accepted directly. WAVE_FORMAT_EXTENSIBLE
// (0xFFFE) is accepted only when its SubFormat GUID indicates PCM — the raw sample data is
// then byte-identical to standard PCM and we normalize it downstream.
// (0xFFFE) is accepted when its SubFormat GUID indicates PCM (0x0001) or IEEE float
// (0x0003). PCM sample data is byte-identical to standard PCM; float data is converted to
// 24-bit PCM downstream. Either way the vault only ever holds standard PCM.
var audioFormat = BitConverter.ToUInt16(buffer, fmtChunkPos + 8);
var isExtensible = false;
var isFloat = false;
if (audioFormat == 0xFFFE)
{
// EXTENSIBLE requires the full extension: 16 base + 2 cbSize + 22 extension = 40 bytes.
@@ -180,14 +194,23 @@ public class AudioProcessor
}
// SubFormat GUID begins 24 bytes into the fmt chunk data (fmtChunkPos + 8 + 24). Its
// first two bytes are the little-endian format tag; 0x0001 == WAVE_FORMAT_PCM.
// first two bytes are the little-endian format tag: 0x0001 == WAVE_FORMAT_PCM,
// 0x0003 == WAVE_FORMAT_IEEE_FLOAT.
var subFormatPos = fmtChunkPos + 8 + 24;
if (buffer[subFormatPos] != 0x01 || buffer[subFormatPos + 1] != 0x00)
var subFormatTag = BitConverter.ToUInt16(buffer, subFormatPos);
if (subFormatTag == 0x0001)
{
return new WavValidationResult { IsValid = false, ErrorMessage = "Invalid data: EXTENSIBLE SubFormat is not PCM" };
isExtensible = true;
}
else if (subFormatTag == 0x0003)
{
isExtensible = true;
isFloat = true;
}
else
{
return new WavValidationResult { IsValid = false, ErrorMessage = "Invalid data: EXTENSIBLE SubFormat is neither PCM nor IEEE float" };
}
isExtensible = true;
}
else if (audioFormat != 1)
{
@@ -206,7 +229,8 @@ public class AudioProcessor
IsValid = true,
FmtChunkPos = fmtChunkPos,
DataChunkPos = dataChunkPos,
IsExtensible = isExtensible
IsExtensible = isExtensible,
IsFloat = isFloat
};
}
@@ -224,13 +248,19 @@ public class AudioProcessor
// For EXTENSIBLE the offset-22 field is the container width; the true sample depth lives in
// wValidBitsPerSample (fmtChunkPos + 8 + 18). They usually match (Bandcamp 24-bit = 24/24)
// but the valid bits are authoritative for the normalized header and metadata.
// Note: padded-container EXTENSIBLE (e.g. 24-bit valid in a 32-bit container) is not yet
// supported — the mismatched BlockAlign will cause ValidateAudioParameters to throw and fall
// back to defaults. This is an accepted gap as of this fix.
// but the valid bits are authoritative for the normalized header and metadata. When they
// differ (e.g. 24-bit valid in a 32-bit container) we keep the container width separately so
// ValidateAudioParameters can reconcile against the header BlockAlign and NormalizeToStandardPcm
// can re-pack the padded frames.
var containerBitsPerSample = 0;
if (validation.IsExtensible)
{
bitsPerSample = BitConverter.ToUInt16(buffer, validation.FmtChunkPos + 8 + 18);
var validBits = BitConverter.ToUInt16(buffer, validation.FmtChunkPos + 8 + 18);
if (validBits != bitsPerSample)
{
containerBitsPerSample = bitsPerSample;
}
bitsPerSample = validBits;
}
var duration = byteRate > 0 ? (double)dataSize / byteRate : 0.0;
@@ -243,10 +273,12 @@ public class AudioProcessor
SampleRate = (int)sampleRate,
Channels = channels,
BitsPerSample = bitsPerSample,
ContainerBitsPerSample = containerBitsPerSample,
BlockAlign = blockAlign,
DataSize = (int)dataSize,
DataChunkPos = validation.DataChunkPos,
IsExtensible = validation.IsExtensible
IsExtensible = validation.IsExtensible,
IsFloat = validation.IsFloat
};
}
@@ -273,7 +305,11 @@ public class AudioProcessor
throw new InvalidDataException($"Unsupported bit depth: {metadata.BitsPerSample}");
}
var expectedBlockAlign = metadata.Channels * (metadata.BitsPerSample / 8);
// The header BlockAlign reflects the container width, not the valid bit depth. For a padded
// EXTENSIBLE container (e.g. 24-in-32) the container width is authoritative for this check;
// NormalizeToStandardPcm re-packs the frames down to the valid depth afterwards.
var blockAlignBits = metadata.IsPaddedContainer ? metadata.ContainerBitsPerSample : metadata.BitsPerSample;
var expectedBlockAlign = metadata.Channels * (blockAlignBits / 8);
if (metadata.BlockAlign != expectedBlockAlign)
{
throw new InvalidDataException($"Invalid block align: expected {expectedBlockAlign}, got {metadata.BlockAlign}");
@@ -281,21 +317,49 @@ public class AudioProcessor
}
/// <summary>
/// Rebuilds an EXTENSIBLE-PCM WAV as a canonical 44-byte-header standard PCM WAV (audioFormat = 1).
/// The sample bytes are copied verbatim — EXTENSIBLE-PCM data is byte-identical to standard PCM —
/// only the header is replaced, so the vault stores a format the streaming pipeline already handles.
/// Rebuilds an EXTENSIBLE WAV as a canonical 44-byte-header standard PCM WAV (audioFormat = 1)
/// so the vault only ever holds a format the streaming pipeline already handles. Three source
/// shapes are normalized:
/// <list type="bullet">
/// <item>EXTENSIBLE-PCM (depth == container): sample bytes are byte-identical to standard PCM and
/// copied verbatim; only the header is replaced.</item>
/// <item>IEEE float: 32-bit float samples are converted to 24-bit signed integer PCM.</item>
/// <item>Padded container (e.g. 24-in-32): the padding/sign-extension bytes are stripped, keeping
/// the lowest valid bytes per sample.</item>
/// </list>
/// The output header always reports the valid bit depth (<see cref="WavMetadata.BitsPerSample"/>).
/// </summary>
private byte[] NormalizeToStandardPcm(byte[] buffer, WavMetadata metadata)
{
// Clamp the declared data size to what is actually present; some encoders overshoot.
var dataStart = metadata.DataChunkPos + 8;
var available = buffer.Length - dataStart;
var dataSize = Math.Min(metadata.DataSize, available);
var srcDataSize = Math.Min(metadata.DataSize, available);
byte[] dataBytes;
int outBitsPerSample;
if (metadata.IsFloat)
{
dataBytes = ConvertFloatTo24BitPcm(buffer, dataStart, srcDataSize);
outBitsPerSample = 24;
}
else if (metadata.IsPaddedContainer)
{
dataBytes = RepackPaddedContainer(buffer, dataStart, srcDataSize, metadata.ContainerBitsPerSample, metadata.BitsPerSample);
outBitsPerSample = metadata.BitsPerSample;
}
else
{
dataBytes = new byte[srcDataSize];
Array.Copy(buffer, dataStart, dataBytes, 0, srcDataSize);
outBitsPerSample = metadata.BitsPerSample;
}
var dataSize = dataBytes.Length;
const int headerSize = 44;
var result = new byte[headerSize + dataSize];
var blockAlign = (ushort)(metadata.Channels * (metadata.BitsPerSample / 8));
var blockAlign = (ushort)(metadata.Channels * (outBitsPerSample / 8));
var byteRate = (uint)(metadata.SampleRate * blockAlign);
// RIFF header
@@ -311,17 +375,70 @@ public class AudioProcessor
BitConverter.GetBytes((uint)metadata.SampleRate).CopyTo(result, 24);
BitConverter.GetBytes(byteRate).CopyTo(result, 28);
BitConverter.GetBytes(blockAlign).CopyTo(result, 32);
BitConverter.GetBytes((ushort)metadata.BitsPerSample).CopyTo(result, 34);
BitConverter.GetBytes((ushort)outBitsPerSample).CopyTo(result, 34);
// data chunk
System.Text.Encoding.ASCII.GetBytes("data").CopyTo(result, 36);
BitConverter.GetBytes((uint)dataSize).CopyTo(result, 40);
Array.Copy(buffer, dataStart, result, headerSize, dataSize);
Array.Copy(dataBytes, 0, result, headerSize, dataSize);
return result;
}
/// <summary>
/// Converts 32-bit little-endian IEEE float samples (range [-1.0, 1.0]) to 24-bit signed PCM.
/// Each 4-byte source sample becomes 3 little-endian output bytes; output size is 3/4 of input.
/// Trailing bytes that do not form a complete 4-byte sample are ignored.
/// </summary>
private static byte[] ConvertFloatTo24BitPcm(byte[] buffer, int dataStart, int dataSize)
{
var sampleCount = dataSize / 4;
var output = new byte[sampleCount * 3];
for (int i = 0; i < sampleCount; i++)
{
var sample = BitConverter.ToSingle(buffer, dataStart + i * 4);
var value = (int)(sample * 8388607.0);
value = Math.Clamp(value, -8388608, 8388607);
var o = i * 3;
output[o] = (byte)(value & 0xFF);
output[o + 1] = (byte)((value >> 8) & 0xFF);
output[o + 2] = (byte)((value >> 16) & 0xFF);
}
return output;
}
/// <summary>
/// Strips container padding from a padded-container EXTENSIBLE WAV (e.g. 24-bit valid samples
/// stored in 32-bit containers), keeping only the lowest <paramref name="validBits"/> bytes of
/// each little-endian sample. Output size is (validBits/containerBits) of input.
/// Trailing bytes that do not form a complete container sample are ignored.
/// </summary>
private static byte[] RepackPaddedContainer(byte[] buffer, int dataStart, int dataSize, int containerBits, int validBits)
{
var containerBytes = containerBits / 8;
var validBytes = validBits / 8;
var sampleCount = dataSize / containerBytes;
var output = new byte[sampleCount * validBytes];
for (int i = 0; i < sampleCount; i++)
{
var src = dataStart + i * containerBytes;
var dst = i * validBytes;
// Little-endian: the valid sample occupies the low bytes; the upper bytes are padding /
// sign extension and are discarded.
for (int b = 0; b < validBytes; b++)
{
output[dst + b] = buffer[src + b];
}
}
return output;
}
/// <summary>
/// Returns default WAV metadata for fallback scenarios
/// </summary>
@@ -389,11 +506,26 @@ public class AudioProcessor
public int Bitrate { get; set; }
public int SampleRate { get; set; }
public int Channels { get; set; }
/// <summary>The valid sample depth — for EXTENSIBLE, wValidBitsPerSample.</summary>
public int BitsPerSample { get; set; }
/// <summary>
/// The container sample width for a padded EXTENSIBLE WAV whose valid depth is narrower
/// (e.g. 32 for a 24-in-32 file). Zero when the container matches the valid depth.
/// </summary>
public int ContainerBitsPerSample { get; set; }
public int BlockAlign { get; set; }
public int DataSize { get; set; }
public int DataChunkPos { get; set; }
public bool IsExtensible { get; set; }
/// <summary>True when the SubFormat is IEEE float (converted to 24-bit PCM on normalization).</summary>
public bool IsFloat { get; set; }
/// <summary>True when valid samples are stored in a wider container that must be re-packed.</summary>
public bool IsPaddedContainer => ContainerBitsPerSample != 0 && ContainerBitsPerSample != BitsPerSample;
}
/// <summary>
@@ -406,6 +538,9 @@ public class AudioProcessor
public int FmtChunkPos { get; set; }
public int DataChunkPos { get; set; }
public bool IsExtensible { get; set; }
/// <summary>True when the EXTENSIBLE SubFormat is IEEE float rather than PCM.</summary>
public bool IsFloat { get; set; }
}
}
DeepDrftTests/AudioProcessorTests.cs
+263
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@@ -0,0 +1,263 @@
using System.Text;
using DeepDrftContent.Processors;
namespace DeepDrftTests;
/// <summary>
/// Tests for <see cref="AudioProcessor.ProcessWavFileAsync"/> WAV format handling — standard PCM,
/// EXTENSIBLE-PCM, EXTENSIBLE IEEE float, padded 24-in-32, and the default-fallback paths.
/// </summary>
[TestFixture]
public class AudioProcessorTests
{
private const ushort WaveFormatPcm = 0x0001;
private const ushort WaveFormatExtensible = 0xFFFE;
private string _testDir = string.Empty;
[SetUp]
public void SetUp()
{
_testDir = Path.Combine(Path.GetTempPath(), "AudioProcessorTests", Guid.NewGuid().ToString());
Directory.CreateDirectory(_testDir);
}
[TearDown]
public void TearDown()
{
try { Directory.Delete(_testDir, recursive: true); }
catch { /* Best-effort cleanup — ignore failures */ }
}
[Test]
public async Task StandardPcm_RoundTripsUnchanged()
{
var path = await WriteWavAsync(BuildMinimalWav(channels: 2, sampleRate: 44100, bitsPerSample: 16, audioFormat: WaveFormatPcm));
var audio = await new AudioProcessor().ProcessWavFileAsync(path);
Assert.That(audio, Is.Not.Null);
Assert.That(audio!.Duration, Is.GreaterThan(0.0));
Assert.That(audio.Bitrate, Is.GreaterThan(0));
}
[Test]
public async Task ExtensiblePcm_NormalizesToStandardHeader()
{
var subFormat = SubFormatGuid(WaveFormatPcm);
var wav = BuildMinimalWav(channels: 2, sampleRate: 44100, bitsPerSample: 16, audioFormat: WaveFormatExtensible,
subFormatGuid: subFormat, validBitsPerSample: 16);
var path = await WriteWavAsync(wav);
var audio = await new AudioProcessor().ProcessWavFileAsync(path);
Assert.That(audio, Is.Not.Null);
Assert.That(audio!.Duration, Is.GreaterThan(0.0));
Assert.That(audio.Bitrate, Is.GreaterThan(0));
Assert.That(ReadFmtAudioFormat(audio.Buffer), Is.EqualTo(WaveFormatPcm), "Stored buffer must be standard PCM");
}
[Test]
public async Task ExtensibleIeeeFloat_AcceptedAndConverted()
{
// Two stereo frames of 32-bit float samples (range [-1.0, 1.0]).
var samples = FloatBytes(0.5f, -0.5f, 1.0f, -1.0f);
var subFormat = SubFormatGuid(0x0003); // WAVE_FORMAT_IEEE_FLOAT
var wav = BuildMinimalWav(channels: 2, sampleRate: 44100, bitsPerSample: 32, audioFormat: WaveFormatExtensible,
sampleData: samples, subFormatGuid: subFormat, validBitsPerSample: 32);
var path = await WriteWavAsync(wav);
var audio = await new AudioProcessor().ProcessWavFileAsync(path);
Assert.That(audio, Is.Not.Null);
Assert.That(ReadFmtBitsPerSample(audio!.Buffer), Is.EqualTo(16 + 8), "Float must convert to 24-bit PCM");
Assert.That(ReadFmtAudioFormat(audio.Buffer), Is.EqualTo(WaveFormatPcm));
// 4 float samples (4 bytes each) → 4 PCM samples (3 bytes each) = 12 data bytes after the 44-byte header.
Assert.That(audio.Buffer.Length, Is.EqualTo(44 + 12));
// Verify the converted sample values: (int)(sample * 8388607.0), clamped, little-endian 3 bytes.
// 0.5f → 4194303 = 0x3FFFFF → FF FF 3F
// -0.5f → -4194303 = 0xFFC00001 → 24-bit LE: 01 00 C0
// 1.0f → 8388607 = 0x7FFFFF → FF FF 7F
// -1.0f → -8388607 = 0xFF800001 → 24-bit LE: 01 00 80
var expectedData = new byte[] { 0xFF, 0xFF, 0x3F, 0x01, 0x00, 0xC0, 0xFF, 0xFF, 0x7F, 0x01, 0x00, 0x80 };
var actualData = audio.Buffer[44..];
Assert.That(actualData, Is.EqualTo(expectedData), "Float samples must be converted to 24-bit PCM correctly");
}
[Test]
public async Task ExtensiblePadded24in32_AcceptedAndRepacked()
{
// Two stereo frames; each sample is a 24-bit value stored in a 32-bit little-endian container.
var samples = Padded24In32Bytes(0x123456, unchecked((int)0xFFEDCBA9), 0x000001, unchecked((int)0xFF800000));
var subFormat = SubFormatGuid(WaveFormatPcm);
var wav = BuildMinimalWav(channels: 2, sampleRate: 44100, bitsPerSample: 32, audioFormat: WaveFormatExtensible,
sampleData: samples, subFormatGuid: subFormat, validBitsPerSample: 24);
var path = await WriteWavAsync(wav);
var audio = await new AudioProcessor().ProcessWavFileAsync(path);
Assert.That(audio, Is.Not.Null);
Assert.That(ReadFmtBitsPerSample(audio!.Buffer), Is.EqualTo(24), "Padded container must repack to 24-bit");
Assert.That(ReadFmtAudioFormat(audio.Buffer), Is.EqualTo(WaveFormatPcm));
// 4 container samples (4 bytes each) → 4 PCM samples (3 bytes each) = 12 data bytes.
Assert.That(audio.Buffer.Length, Is.EqualTo(44 + 12));
// Verify the repacked sample values: lowest 3 bytes of each 4-byte little-endian container.
// 0x123456 → LE 4 bytes: 56 34 12 00 → keep 3: 56 34 12
// 0xFFEDCBA9 → LE 4 bytes: A9 CB ED FF → keep 3: A9 CB ED
// 0x000001 → LE 4 bytes: 01 00 00 00 → keep 3: 01 00 00
// 0xFF800000 → LE 4 bytes: 00 00 80 FF → keep 3: 00 00 80
var expectedData = new byte[] { 0x56, 0x34, 0x12, 0xA9, 0xCB, 0xED, 0x01, 0x00, 0x00, 0x00, 0x00, 0x80 };
var actualData = audio.Buffer[44..];
Assert.That(actualData, Is.EqualTo(expectedData), "Padded 24-in-32 samples must strip the padding byte correctly");
}
[Test]
public async Task ExtensibleUnsupportedSubFormat_FallsBackToDefaults()
{
var subFormat = SubFormatGuid(0x0005); // WAVE_FORMAT_DOLBY_AC3 — neither PCM nor float
var wav = BuildMinimalWav(channels: 2, sampleRate: 44100, bitsPerSample: 16, audioFormat: WaveFormatExtensible,
subFormatGuid: subFormat, validBitsPerSample: 16);
var path = await WriteWavAsync(wav);
var audio = await new AudioProcessor().ProcessWavFileAsync(path);
Assert.That(audio, Is.Not.Null);
Assert.That(audio!.Duration, Is.EqualTo(180.0), "Unsupported SubFormat must fall back to default metadata");
}
[Test]
public async Task ExtensibleFmtTooSmall_FallsBackToDefaults()
{
// audioFormat=EXTENSIBLE but fmt chunk declares 16 bytes — too small for the extension.
var wav = BuildMinimalWav(channels: 2, sampleRate: 44100, bitsPerSample: 16, audioFormat: WaveFormatExtensible,
forceFmtChunkSize: 16);
var path = await WriteWavAsync(wav);
var audio = await new AudioProcessor().ProcessWavFileAsync(path);
Assert.That(audio, Is.Not.Null);
Assert.That(audio!.Duration, Is.EqualTo(180.0), "Undersized EXTENSIBLE fmt chunk must fall back to default metadata");
}
[Test]
public void TryExtractPcm_FloatWav_ReturnsNull()
{
var subFormat = SubFormatGuid(0x0003);
var wav = BuildMinimalWav(channels: 2, sampleRate: 44100, bitsPerSample: 32, audioFormat: WaveFormatExtensible,
subFormatGuid: subFormat, validBitsPerSample: 32);
var result = new AudioProcessor().TryExtractPcm(wav);
Assert.That(result, Is.Null);
}
[Test]
public void TryExtractPcm_Padded24in32_ReturnsNull()
{
var subFormat = SubFormatGuid(WaveFormatPcm);
var wav = BuildMinimalWav(channels: 2, sampleRate: 44100, bitsPerSample: 32, audioFormat: WaveFormatExtensible,
subFormatGuid: subFormat, validBitsPerSample: 24);
var result = new AudioProcessor().TryExtractPcm(wav);
Assert.That(result, Is.Null);
}
// -- helpers --------------------------------------------------------------------------------
/// <summary>
/// Synthesises a minimal valid WAV buffer. For EXTENSIBLE (audioFormat=0xFFFE) the fmt chunk is
/// 40 bytes and includes cbSize, wValidBitsPerSample, channel mask, and the SubFormat GUID. For
/// standard PCM (audioFormat=1) the fmt chunk is 16 bytes. When <paramref name="sampleData"/> is
/// null a small block of silence sized to the block alignment is used.
/// </summary>
private static byte[] BuildMinimalWav(
int channels,
int sampleRate,
int bitsPerSample,
ushort audioFormat,
byte[]? sampleData = null,
byte[]? subFormatGuid = null,
ushort validBitsPerSample = 0,
uint? forceFmtChunkSize = null)
{
var isExtensible = audioFormat == WaveFormatExtensible;
var fmtChunkSize = forceFmtChunkSize ?? (isExtensible ? 40u : 16u);
var blockAlign = (ushort)(channels * (bitsPerSample / 8));
var byteRate = (uint)(sampleRate * blockAlign);
var data = sampleData ?? new byte[blockAlign * 2];
using var ms = new MemoryStream();
using var w = new BinaryWriter(ms, Encoding.ASCII, leaveOpen: true);
w.Write(Encoding.ASCII.GetBytes("RIFF"));
w.Write((uint)(36 + fmtChunkSize - 16 + data.Length)); // riff size adjusted for fmt extension
w.Write(Encoding.ASCII.GetBytes("WAVE"));
w.Write(Encoding.ASCII.GetBytes("fmt "));
w.Write(fmtChunkSize);
w.Write(audioFormat);
w.Write((ushort)channels);
w.Write((uint)sampleRate);
w.Write(byteRate);
w.Write(blockAlign);
w.Write((ushort)bitsPerSample);
// Only emit the EXTENSIBLE extension when the declared fmt size actually allows for it. A
// forced-small size (fmt=16) leaves audioFormat=EXTENSIBLE but no extension, exercising the
// "fmt too small" fallback.
if (fmtChunkSize >= 40)
{
w.Write((ushort)22); // cbSize
w.Write(validBitsPerSample);
w.Write((uint)0); // channel mask
w.Write(subFormatGuid ?? SubFormatGuid(WaveFormatPcm));
}
w.Write(Encoding.ASCII.GetBytes("data"));
w.Write((uint)data.Length);
w.Write(data);
w.Flush();
return ms.ToArray();
}
/// <summary>Builds a 16-byte SubFormat GUID whose leading 2 bytes are the format tag.</summary>
private static byte[] SubFormatGuid(ushort formatTag)
{
var guid = new byte[16];
guid[0] = (byte)(formatTag & 0xFF);
guid[1] = (byte)((formatTag >> 8) & 0xFF);
// Remaining 14 bytes are the fixed KSDATAFORMAT suffix; their value is irrelevant to parsing.
return guid;
}
private static byte[] FloatBytes(params float[] samples)
{
var bytes = new byte[samples.Length * 4];
for (int i = 0; i < samples.Length; i++)
{
BitConverter.GetBytes(samples[i]).CopyTo(bytes, i * 4);
}
return bytes;
}
/// <summary>Packs each 24-bit sample value into a 32-bit little-endian container.</summary>
private static byte[] Padded24In32Bytes(params int[] samples)
{
var bytes = new byte[samples.Length * 4];
for (int i = 0; i < samples.Length; i++)
{
BitConverter.GetBytes(samples[i]).CopyTo(bytes, i * 4);
}
return bytes;
}
private async Task<string> WriteWavAsync(byte[] wav)
{
var path = Path.Combine(_testDir, Guid.NewGuid() + ".wav");
await File.WriteAllBytesAsync(path, wav);
return path;
}
private static ushort ReadFmtAudioFormat(byte[] standardPcmWav) => BitConverter.ToUInt16(standardPcmWav, 20);
private static ushort ReadFmtBitsPerSample(byte[] standardPcmWav) => BitConverter.ToUInt16(standardPcmWav, 34);
}