确定 Visual Studio 2019 年的 WAV 持续时间

Question

首先，感谢您考虑我的问题。我已经搜索了这个问题的解决方案，但没有找到任何利用现代 Visual Studio features/libraries/namespaces 等...

我需要确定 WAV 音频文件的持续时间（时间长度）。我想在几毫秒内得到结果 - 我可以从那里根据我的需要格式化数据。

能否举例说明如何做到这一点？

谢谢你

Answer 1

文件的元数据将在标准中定义。 wave 文件头已在 another SO question 中介绍，但重点是使用 C sharp。

VB.NET和C sharp的实现应该比较相似。 VB.NET 有一些限制，这意味着这种操作最好用另一种语言来完成。也就是说，新手 VB.NET 程序员几乎没有立即可用的东西，这本身就是一个危险信号，它可能以错误的方式使用 VB.NET。

有一个 project that tries to provide a .NET framework for grabbing metadata，但如果你不想让自己为 Wav 文件这样的依赖项而增加负担，那么你可以使用以下方法获得持续时间。

Dim wavFilePath As String = "Path\To\Your\Wav"
Dim fileReader As New System.IO.FileStream(wavFilePath, System.IO.FileMode.Open)
Dim numChannelsData(2) As Byte
Dim bitsPerSampleData(2) As Byte
Dim sampleRateData(4) As Byte
Dim subChunk2SizeData(4) As Byte

fileReader.Seek(22, System.IO.SeekOrigin.Begin)
fileReader.Read(numChannelsData, 0, 2)
fileReader.Seek(34, System.IO.SeekOrigin.Begin)
fileReader.Read(bitsPerSampleData, 0, 2)
fileReader.Seek(24, System.IO.SeekOrigin.Begin)
fileReader.Read(sampleRateData, 0, 4)
fileReader.Seek(40, System.IO.SeekOrigin.Begin)
fileReader.Read(subChunk2SizeData, 0, 4)

Dim numChannels As Int16 = BitConverter.ToInt16(numChannelsData)
Dim bitsPerSample = BitConverter.ToInt32(sampleRateData)
Dim sampleRate = BitConverter.ToInt16(bitsPerSampleData)
Dim subChunk2Size = BitConverter.ToInt32(subChunk2SizeData)

Dim numSamples = (subChunk2Size * 8) / (numChannels * bitsPerSample)
Dim durationInMilliseconds As Single = 1000 * Convert.ToSingle(numSamples) / (Convert.ToSingle(sampleRate))

Console.WriteLine(durationInMilliseconds)

Answer 2

对于那些搜索此解决方案的人，这里是调试代码。请注意，这里不包括毫秒到时间字符串的转换。另请注意，根据对此帖子的评论，没有标准的 Visual Basic 库可以导出 WAV 文件的持续时间。

选项显式选项严格进口 System.IO

Public Shared Function GetWAVDuration(ByVal strPathAndFilename As String) As String

    REM *** SEE ALSO
    REM *** http://soundfile.sapp.org/doc/WaveFormat/
    REM *** CAUTION
    REM *** On the WaveFormat web page, the positions of the values
    REM *** SampleRate and BitsPerSample have been reversed.
    REM *** 

    REM *** DEFINE LOCAL VARIABLES

    REM *** Define Visual Basic BYTE Array Types
    Dim byNumberOfChannels() As Byte
    Dim bySamplesPerSec() As Byte
    Dim byBitsPerSample() As Byte
    Dim bySubChunkToSizeData() As Byte

    Dim nNumberOfChannels As Int16
    Dim nSamplesPerSec As Int16
    Dim nBitsPerSample As Int32
    Dim nSubChunkToSizeData As Int32

    Dim dNumberOfSamples As Double
    Dim nDurationInMillis As Int32

    Dim strDuration As String

    REM *** INITIALIZE LOCAL VARIABLES
    byNumberOfChannels = New Byte(2) {}
    bySamplesPerSec = New Byte(2) {}
    byBitsPerSample = New Byte(4) {}
    bySubChunkToSizeData = New Byte(4) {}

    nNumberOfChannels = 0
    nSamplesPerSec = 0
    nBitsPerSample = 0L
    nSubChunkToSizeData = 0L

    dNumberOfSamples = 0.0
    nDurationInMillis = 0

    strDuration = ""

    REM *** Initialize the return string value
    GetWAVDuration = ""

    REM ***************************************************************************

    REM *** Open the Input File for READ Operations
    Using fsFileStream = File.OpenRead(strPathAndFilename)

        REM *** Get the Number of Audio Channels
        fsFileStream.Seek(22, SeekOrigin.Begin)
        fsFileStream.Read(byNumberOfChannels, 0, 2)

        REM *** Get the Number of Bits Per Audio Sample
        fsFileStream.Seek(24, SeekOrigin.Begin)
        fsFileStream.Read(byBitsPerSample, 0, 4)

        REM *** Get the number of samples taken per second
        fsFileStream.Seek(34, SeekOrigin.Begin)
        fsFileStream.Read(bySamplesPerSec, 0, 2)

        REM *** Retrieve the size of the WAV data
        REM *** payload in the file
        fsFileStream.Seek(40, SeekOrigin.Begin)
        fsFileStream.Read(bySubChunkToSizeData, 0, 4)

    End Using

    REM *** Convert Values from their BYTE representation

    nNumberOfChannels = BitConverter.ToInt16(byNumberOfChannels, 0)
    nBitsPerSample = BitConverter.ToInt32(byBitsPerSample, 0)
    nSamplesPerSec = BitConverter.ToInt16(bySamplesPerSec, 0)
    nSubChunkToSizeData = BitConverter.ToInt32(bySubChunkToSizeData, 0)

    REM *** Compute the Duration of the WAV File
    REM *** Derives the duration in milliseconds

    REM *** Determine the number of Sound Samples 
    dNumberOfSamples = (nSubChunkToSizeData * 8) / (nNumberOfChannels * nBitsPerSample)
    nDurationInMillis = Convert.ToInt32(1000 * Convert.ToSingle(dNumberOfSamples) / Convert.ToSingle(nSamplesPerSec))

    REM *** Convert the time in Milliseconds to a string format
    REM *** represented by "hh:mm:ss"
    strDuration = ConvertMillisToTimeString(nDurationInMillis)

    REM *** POST METHOD RETURNS
    GetWAVDuration = strDuration

End Function

确定 Visual Studio 2019 年的 WAV 持续时间

Determine WAV Duration Time in Visual Studio 2019

.net

vb.net

audio

visual-studio-2019

wav