True Streaming Support Draft
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daniel-c-harvey
@@ -46,101 +46,198 @@ public class AudioProcessor
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}
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/// <summary>
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/// Extracts metadata from WAV file buffer
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/// Extracts metadata from WAV file buffer with comprehensive validation
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/// </summary>
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private WavMetadata ExtractWavMetadata(byte[] buffer)
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{
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try
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{
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// WAV file format parsing
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// RIFF header starts at byte 0
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if (buffer.Length < 44)
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var validationResult = ValidateWavStructure(buffer);
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if (!validationResult.IsValid)
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{
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throw new InvalidDataException("WAV file too short to contain valid header");
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throw new InvalidDataException($"WAV validation failed: {validationResult.ErrorMessage}");
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}
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// Check RIFF signature
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var riffSignature = System.Text.Encoding.ASCII.GetString(buffer, 0, 4);
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if (riffSignature != "RIFF")
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{
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throw new InvalidDataException("Invalid WAV file: Missing RIFF signature");
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}
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// Check WAVE format
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var waveSignature = System.Text.Encoding.ASCII.GetString(buffer, 8, 4);
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if (waveSignature != "WAVE")
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{
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throw new InvalidDataException("Invalid WAV file: Missing WAVE signature");
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}
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// Find fmt chunk
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var fmtChunkPos = FindChunk(buffer, "fmt ");
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if (fmtChunkPos == -1)
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{
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throw new InvalidDataException("Invalid WAV file: Missing fmt chunk");
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}
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// Parse fmt chunk
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var fmtChunkSize = BitConverter.ToUInt32(buffer, fmtChunkPos + 4);
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var sampleRate = BitConverter.ToUInt32(buffer, fmtChunkPos + 12);
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var byteRate = BitConverter.ToUInt32(buffer, fmtChunkPos + 16);
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var channels = BitConverter.ToUInt16(buffer, fmtChunkPos + 10);
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var bitsPerSample = BitConverter.ToUInt16(buffer, fmtChunkPos + 22);
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// Find data chunk
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var dataChunkPos = FindChunk(buffer, "data");
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if (dataChunkPos == -1)
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{
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throw new InvalidDataException("Invalid WAV file: Missing data chunk");
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}
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var dataSize = BitConverter.ToUInt32(buffer, dataChunkPos + 4);
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// Calculate duration
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var duration = (double)dataSize / byteRate;
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var metadata = ParseWavMetadata(buffer, validationResult);
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ValidateAudioParameters(metadata);
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// Calculate bitrate (bits per second / 1000 for kbps)
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var bitrate = (int)((sampleRate * channels * bitsPerSample) / 1000);
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return new WavMetadata
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{
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Duration = duration,
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Bitrate = bitrate,
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SampleRate = (int)sampleRate,
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Channels = channels,
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BitsPerSample = bitsPerSample
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};
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return metadata;
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}
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catch (Exception ex)
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{
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// Fallback to basic metadata if parsing fails
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Console.WriteLine($"Warning: Could not parse WAV metadata: {ex.Message}");
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return new WavMetadata
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{
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Duration = 180.0, // Default 3 minutes
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Bitrate = 1411, // Default CD quality bitrate for WAV
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SampleRate = 44100,
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Channels = 2,
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BitsPerSample = 16
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};
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Console.WriteLine($"Warning: WAV parsing failed, using defaults: {ex.Message}");
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return GetDefaultWavMetadata();
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}
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}
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/// <summary>
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/// Validates WAV file structure and returns parsing information
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/// </summary>
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private WavValidationResult ValidateWavStructure(byte[] buffer)
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{
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if (buffer.Length < 44)
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{
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return new WavValidationResult { IsValid = false, ErrorMessage = "File too short" };
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}
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// Validate RIFF signature
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var riffSignature = System.Text.Encoding.ASCII.GetString(buffer, 0, 4);
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if (riffSignature != "RIFF")
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{
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return new WavValidationResult { IsValid = false, ErrorMessage = "Invalid RIFF signature" };
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}
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// Validate WAVE signature
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var waveSignature = System.Text.Encoding.ASCII.GetString(buffer, 8, 4);
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if (waveSignature != "WAVE")
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{
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return new WavValidationResult { IsValid = false, ErrorMessage = "Invalid WAVE signature" };
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}
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// Find and validate fmt chunk
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var fmtChunkPos = FindChunk(buffer, "fmt ");
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if (fmtChunkPos == -1)
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{
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return new WavValidationResult { IsValid = false, ErrorMessage = "Missing fmt chunk" };
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}
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var fmtChunkSize = BitConverter.ToUInt32(buffer, fmtChunkPos + 4);
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if (fmtChunkSize < 16)
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{
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return new WavValidationResult { IsValid = false, ErrorMessage = "fmt chunk too small" };
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}
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// Validate audio format (PCM only)
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var audioFormat = BitConverter.ToUInt16(buffer, fmtChunkPos + 8);
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if (audioFormat != 1)
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{
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return new WavValidationResult { IsValid = false, ErrorMessage = "Only PCM format supported" };
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}
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// Find data chunk
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var dataChunkPos = FindChunk(buffer, "data");
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if (dataChunkPos == -1)
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{
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return new WavValidationResult { IsValid = false, ErrorMessage = "Missing data chunk" };
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}
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return new WavValidationResult
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{
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IsValid = true,
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FmtChunkPos = fmtChunkPos,
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DataChunkPos = dataChunkPos
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};
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}
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/// <summary>
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/// Parses WAV metadata from validated buffer
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/// </summary>
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private WavMetadata ParseWavMetadata(byte[] buffer, WavValidationResult validation)
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{
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var channels = BitConverter.ToUInt16(buffer, validation.FmtChunkPos + 10);
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var sampleRate = BitConverter.ToUInt32(buffer, validation.FmtChunkPos + 12);
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var byteRate = BitConverter.ToUInt32(buffer, validation.FmtChunkPos + 16);
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var blockAlign = BitConverter.ToUInt16(buffer, validation.FmtChunkPos + 20);
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var bitsPerSample = BitConverter.ToUInt16(buffer, validation.FmtChunkPos + 22);
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var dataSize = BitConverter.ToUInt32(buffer, validation.DataChunkPos + 4);
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var duration = byteRate > 0 ? (double)dataSize / byteRate : 0.0;
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var bitrate = (int)((sampleRate * channels * bitsPerSample) / 1000);
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return new WavMetadata
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{
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Duration = duration,
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Bitrate = bitrate,
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SampleRate = (int)sampleRate,
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Channels = channels,
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BitsPerSample = bitsPerSample,
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BlockAlign = blockAlign,
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DataSize = (int)dataSize
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};
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}
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/// <summary>
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/// Validates audio parameters for reasonableness
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/// </summary>
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private void ValidateAudioParameters(WavMetadata metadata)
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{
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var validSampleRates = new[] { 8000, 11025, 16000, 22050, 44100, 48000, 88200, 96000, 176400, 192000 };
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var validBitDepths = new[] { 8, 16, 24, 32 };
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if (metadata.Channels < 1 || metadata.Channels > 8)
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{
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throw new InvalidDataException($"Invalid channel count: {metadata.Channels}");
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}
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if (!validSampleRates.Contains(metadata.SampleRate))
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{
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throw new InvalidDataException($"Unsupported sample rate: {metadata.SampleRate}");
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}
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if (!validBitDepths.Contains(metadata.BitsPerSample))
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{
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throw new InvalidDataException($"Unsupported bit depth: {metadata.BitsPerSample}");
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}
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var expectedBlockAlign = metadata.Channels * (metadata.BitsPerSample / 8);
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if (metadata.BlockAlign != expectedBlockAlign)
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{
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throw new InvalidDataException($"Invalid block align: expected {expectedBlockAlign}, got {metadata.BlockAlign}");
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}
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}
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/// <summary>
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/// Returns default WAV metadata for fallback scenarios
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/// </summary>
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private WavMetadata GetDefaultWavMetadata()
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{
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return new WavMetadata
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{
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Duration = 180.0,
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Bitrate = 1411,
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SampleRate = 44100,
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Channels = 2,
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BitsPerSample = 16,
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BlockAlign = 4,
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DataSize = 0
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};
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}
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/// <summary>
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/// Finds a chunk in the WAV file buffer
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/// Finds a chunk in the WAV file buffer with proper alignment handling
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/// </summary>
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private int FindChunk(byte[] buffer, string chunkId)
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{
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var chunkBytes = System.Text.Encoding.ASCII.GetBytes(chunkId);
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int offset = 12; // Start after RIFF header
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for (int i = 12; i < buffer.Length - 8; i += 4)
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while (offset <= buffer.Length - 8)
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{
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if (buffer[i] == chunkBytes[0] &&
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buffer[i + 1] == chunkBytes[1] &&
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buffer[i + 2] == chunkBytes[2] &&
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buffer[i + 3] == chunkBytes[3])
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// Check for chunk signature match
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bool match = true;
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for (int i = 0; i < 4; i++)
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{
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return i;
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if (buffer[offset + i] != chunkBytes[i])
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{
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match = false;
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break;
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}
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}
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if (match)
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{
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return offset;
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}
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// Move to next chunk with proper alignment
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if (offset + 4 < buffer.Length)
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{
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var chunkSize = BitConverter.ToUInt32(buffer, offset + 4);
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offset += 8 + (int)((chunkSize + 1) & ~1U); // Ensure even alignment
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}
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else
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{
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break;
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}
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}
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@@ -148,7 +245,7 @@ public class AudioProcessor
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}
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/// <summary>
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/// WAV file metadata
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/// WAV file metadata with complete audio information
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/// </summary>
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private class WavMetadata
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{
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@@ -157,5 +254,18 @@ public class AudioProcessor
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public int SampleRate { get; set; }
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public int Channels { get; set; }
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public int BitsPerSample { get; set; }
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public int BlockAlign { get; set; }
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public int DataSize { get; set; }
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}
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/// <summary>
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/// Result of WAV structure validation
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/// </summary>
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private class WavValidationResult
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{
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public bool IsValid { get; set; }
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public string ErrorMessage { get; set; } = string.Empty;
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public int FmtChunkPos { get; set; }
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public int DataChunkPos { get; set; }
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}
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}
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