public static FromFormatChunk ( |
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br | Binary reader | |
formatChunkLength | int | Format chunk length |
Результат |
/// <summary> /// Reads the header part of a WAV file from a stream /// </summary> /// <param name="stream">The stream, positioned at the start of audio data</param> /// <param name="format">The format found</param> /// <param name="dataChunkPosition">The position of the data chunk</param> /// <param name="dataChunkLength">The length of the data chunk</param> /// <param name="chunks">Additional chunks found</param> public static void ReadWaveHeader(Stream stream, out WaveFormat format, out long dataChunkPosition, out int dataChunkLength, List <RiffChunk> chunks) { dataChunkPosition = -1; format = null; BinaryReader br = new BinaryReader(stream); if (br.ReadInt32() != WaveInterop.mmioStringToFOURCC("RIFF", 0)) { throw new FormatException("Not a WAVE file - no RIFF header"); } uint fileSize = br.ReadUInt32(); // read the file size (minus 8 bytes) if (br.ReadInt32() != WaveInterop.mmioStringToFOURCC("WAVE", 0)) { throw new FormatException("Not a WAVE file - no WAVE header"); } int dataChunkID = WaveInterop.mmioStringToFOURCC("data", 0); int formatChunkId = WaveInterop.mmioStringToFOURCC("fmt ", 0); dataChunkLength = 0; // sometimes a file has more data than is specified after the RIFF header long stopPosition = Math.Min(fileSize + 8, stream.Length); // this -8 is so we can be sure that there are at least 8 bytes for a chunk id and length while (stream.Position <= stopPosition - 8) { Int32 chunkIdentifier = br.ReadInt32(); Int32 chunkLength = br.ReadInt32(); if (chunkIdentifier == dataChunkID) { dataChunkPosition = stream.Position; dataChunkLength = chunkLength; stream.Position += chunkLength; } else if (chunkIdentifier == formatChunkId) { format = WaveFormat.FromFormatChunk(br, chunkLength); } else { if (chunks != null) { chunks.Add(new RiffChunk(chunkIdentifier, chunkLength, stream.Position)); } stream.Position += chunkLength; } } if (format == null) { throw new FormatException("Invalid WAV file - No fmt chunk found"); } if (dataChunkPosition == -1) { throw new FormatException("Invalid WAV file - No data chunk found"); } }
/// <summary> /// Reads the header part of a WAV file from a stream /// </summary> /// <param name="stream">The stream, positioned at the start of audio data</param> /// <param name="format">The format found</param> /// <param name="dataChunkPosition">The position of the data chunk</param> /// <param name="dataChunkLength">The length of the data chunk</param> /// <param name="chunks">Additional chunks found</param> public static void ReadWaveHeader(Stream stream, out WaveFormat format, out long dataChunkPosition, out int dataChunkLength, List <RiffChunk> chunks) { dataChunkPosition = -1; format = null; BinaryReader br = new BinaryReader(stream); if (br.ReadInt32() != WaveInterop.mmioStringToFOURCC("RIFF", 0)) { throw new FormatException("Not a WAVE file - no RIFF header"); } uint fileSize = br.ReadUInt32(); // read the file size (minus 8 bytes) if (br.ReadInt32() != WaveInterop.mmioStringToFOURCC("WAVE", 0)) { throw new FormatException("Not a WAVE file - no WAVE header"); } int dataChunkID = WaveInterop.mmioStringToFOURCC("data", 0); int formatChunkId = WaveInterop.mmioStringToFOURCC("fmt ", 0); dataChunkLength = 0; // sometimes a file has more data than is specified after the RIFF header long stopPosition = Math.Min(fileSize + 8, stream.Length); // this -8 is so we can be sure that there are at least 8 bytes for a chunk id and length while (stream.Position <= stopPosition - 8) { Int32 chunkIdentifier = br.ReadInt32(); Int32 chunkLength = br.ReadInt32(); if (chunkIdentifier == dataChunkID) { dataChunkPosition = stream.Position; dataChunkLength = chunkLength; stream.Position += chunkLength; } else if (chunkIdentifier == formatChunkId) { format = WaveFormat.FromFormatChunk(br, chunkLength); } else { // check for invalid chunk length if (chunkLength < 0 || chunkLength > stream.Length - stream.Position) { Debug.Assert(false, String.Format("Invalid chunk length {0}, pos: {1}. length: {2}", chunkLength, stream.Position, stream.Length)); // an exception will be thrown further down if we haven't got a format and data chunk yet, // otherwise we will tolerate this file despite it having corrupt data at the end break; } if (chunks != null) { chunks.Add(new RiffChunk(chunkIdentifier, chunkLength, stream.Position)); } stream.Position += chunkLength; } } if (format == null) { throw new FormatException("Invalid WAV file - No fmt chunk found"); } if (dataChunkPosition == -1) { throw new FormatException("Invalid WAV file - No data chunk found"); } }