Reading data in WAV file

[Gsquared]

Hi folks,

I need to read a sound file in wav format that I saved using the AudioRecord library. I can load and play it with the media player, but I need to be able to access the individual values in the wav file for further analysis. I tried "File.ReadList", but got gibberish in the Log window when debugging. Can anyone help me?

Thanks, G^2

 

[kickaha]

Use File.ReadBytes

 

[Gsquared]

reading WAV file

kickaha,

Do you mean "InputStream.ReadBytes"? If so, I will have to do some reading on inputstreams - haven't used this function yet.

 

[kickaha]

Yes, my previous post contained a link to the relevant page in the manual.

Basically you can read the file into an array of bytes so that you can work on the file at byte level.

 

[Gsquared]

reading WAV file

Here's the code fragment I tried for reading the WAV file:


Dim buffer() As Byte
Dim InputStream1 As InputStream

File.OpenInput(File.DirDefaultExternal, "test.wav")
InputStream1.ReadBytes(buffer,44,buffer.Length)
Log("First"&buffer(0))
Log("Second"&buffer(1))

I received a runtime error indicated that I need to initialize the object in the ReadBytes line. I'm not sure how to do this.

 

[poseidon]

re

'Reads a file to byte array.

Sub ReadAllBytes(folder As String , filename As String ) As Byte()
   Try 
      Dim in As InputStream
      in = File.OpenInput(folder,filename)
      Dim out As OutputStream
      out.InitializeToBytesArray(1)
      File.Copy2(in, out)

      Dim data() As Byte
      data = out.ToBytesArray
      
      out.Close
      in.Close 
      out.Flush
      
      Return data 
   Catch 
      Return Null 
   End Try 
End Sub

 

[Gsquared]

reading WAV file

Thanks Poseidon!

That seems to work. I just made one change to your Sub - I moved the "Dim data() As Byte" statement to "Process_Globals". If I understand the Sub correctly, the WAV file must only contain byte data, right? What about skipping the header on WAV files with one?

 

[poseidon]

re

nah, this is a ^function.. so

Sub Button1_Click
dim wav() as byte

'here set the bytes of file to local variable wav
wav = ReadAllBytes(files.external,"test.wav")

'here loop the byte array (aka wav file)

for i=0 to wav.length
'what you want to do..(?)
'to read the byte just
'if wav(i) = 

next 

End Sub

according to this
Ring This... Wave File Format

first you have to read the chunksize (size of WAVE section chunck) then make a loop equal to chunksize, is a little bit complex if you havent 'play' with bytes again...

 

[NeoTechni]

How would you do this while recording?

 

[poseidon]

re

you cant do it^ while recording..

the requester ask :

I need to read a sound file in wav format that I saved using the AudioRecord library