为内存中的流创建有效的wav文件头 [英] Create valid wav file header for streams in memory

问题描述

我将原始无头 wav 音频数据作为MemoryStream.

I have raw-headerless wav audio data as MemoryStreams.

Stream rawAudioStream = Producer.GetRawAudioFileStream(...);

我知道这些流的数据格式:

I know those streams data format:

// WaveFormat(int rate, int bits, int channels);
WaveFormat waveformat = new WaveFormat(8000, 16, 1);

我想要的是以编程方式为这些内存流添加正确的头信息，而无需将其写入物理文件.

What I want is to add programmatically right header info for those memory streams without writing them to a physical file.

我该怎么办?

PS::我检查了NAudio库，但只找到了一种通过将流写入实际文件的方式来创建标头的方法，该文件不适合我的情况.

PS: I checked the NAudio Library but only found a way to create a header by writing streams to really-physical files which is not suitable for my situation.

var waveformat = new WaveFormat(8000,16,1);

var reader = new RawSourceWaveStream(rawAudioMemStream, waveformat);

using (var convertedStream = WaveFormatConversionStream.CreatePcmStream(reader))    
{
    WaveFileWriter.CreateWaveFile(fileName, convertedStream);     
}

rawAudioMemStream.Close();

推荐答案

下面的代码会将Wav标头写入MemoryStream的开头.这意味着您需要先将标头写入流 ，然后才能编写示例.否则，流开始时的样本将被元数据覆盖，

The below code will write a Wav header to the beginning of a MemoryStream. Which means you'll need to write the header to your stream first, and then you can write your samples. Otherwise the samples at the start of your stream will get overwritten with meta data,

// totalSampleCount needs to be the combined count of samples of all channels. So if the left and right channels contain 1000 samples each, then totalSampleCount should be 2000.
// isFloatingPoint should only be true if the audio data is in 32-bit floating-point format.

private void WriteWavHeader(MemoryStream stream, bool isFloatingPoint, ushort channelCount, ushort bitDepth, int sampleRate, int totalSampleCount)
{
    stream.Position = 0;

    // RIFF header.
    // Chunk ID.
    stream.Write(Encoding.ASCII.GetBytes("RIFF"), 0, 4);

    // Chunk size.
    stream.Write(BitConverter.GetBytes(((bitDepth / 8) * totalSampleCount) + 36), 0, 4);

    // Format.
    stream.Write(Encoding.ASCII.GetBytes("WAVE"), 0, 4);



    // Sub-chunk 1.
    // Sub-chunk 1 ID.
    stream.Write(Encoding.ASCII.GetBytes("fmt "), 0, 4);

    // Sub-chunk 1 size.
    stream.Write(BitConverter.GetBytes(16), 0, 4);

    // Audio format (floating point (3) or PCM (1)). Any other format indicates compression.
    stream.Write(BitConverter.GetBytes((ushort)(isFloatingPoint ? 3 : 1)), 0, 2);

    // Channels.
    stream.Write(BitConverter.GetBytes(channelCount), 0, 2);

    // Sample rate.
    stream.Write(BitConverter.GetBytes(sampleRate), 0, 4);

    // Bytes rate.
    stream.Write(BitConverter.GetBytes(sampleRate * channelCount * (bitDepth / 8)), 0, 4);

    // Block align.
    stream.Write(BitConverter.GetBytes((ushort)channelCount * (bitDepth / 8)), 0, 2);

    // Bits per sample.
    stream.Write(BitConverter.GetBytes(bitDepth), 0, 2);



    // Sub-chunk 2.
    // Sub-chunk 2 ID.
    stream.Write(Encoding.ASCII.GetBytes("data"), 0, 4);

    // Sub-chunk 2 size.
    stream.Write(BitConverter.GetBytes((bitDepth / 8) * totalSampleCount), 0, 4);
}

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