[Speex-dev] WaveIn/WaveOut and Speex

[Evgueni Tsygankov]

Thank you for such a quick response.

The only reason I started with Char buffers is because WaveIn and WaveOut on Windows XP accept/emit WAVEHDR structures, which store audio data in LPSTR, which is Char*. 

typedef struct { 
    LPSTR      lpData; 
    DWORD      dwBufferLength; 
	...
} WAVEHDR; 

When I was going from Char to float and back looked very wrong to me as well, but I was just not sure (and still am) how to translate the Char* audio stream generated by WaveIn to a format that can be understood by Speex. Would using speex_decode_int and speex_encode_int instead of speex_decode and speex_encode be the answer?

Thank you,

Evgueni Tsygankov
www.sqlanswers.com
www.rusmex.com


-----Original Message-----
From: Jean-Marc Valin [mailto:jean-marc.valin at usherbrooke.ca] 
Sent: Sunday, November 04, 2007 9:33 PM
To: Evgueni Tsygankov
Cc: speex-dev at xiph.org
Subject: Re: [Speex-dev] WaveIn/WaveOut and Speex

I'm not sure what input/output format you're trying to use, but it looks
wrong. You're using the float functions that take +-32767 values and
you're feeding (or converting) chars. Unless your machine has very
special chars (which I doubt), a +-32767 value just isn't going to fit
in. This has nothing to do with Speex BTW, it's just handling the audio
data properly.

	Jean-Marc


Evgueni Tsygankov wrote:
> Hello,
> 
>  
> 
> I know my question has been asked before because I spent the last week
> searching the web for how to use Speex in combination with
> WaveIn/WaveOut and I ran into a few posts, but none of them answer the
> question. There is still a lot of confusion how to use WaveIn/WaveOut
> and Speex by junior developers such as myself. Even after examining code
> for SpeexDec and SpeexEnc, I cannot get clear sound when I try to
> 
>  
> 
> Get PCM Char buffer from the microphone
> 
> Encode Char buffer using Speex
> 
> Decode Speex Char buffer into PCM char buffer
> 
> Play PCM char buffer using WaveOut
> 
>  
> 
> The end-result is very distorted sound.
> 
>  
> 
>  
> 
> I use the following PCM format:
> 
>  
> 
> waveFormat.nChannels = 1;
> 
> waveFormat.nSamplesPerSec = 8000;
> 
> waveFormat.wBitsPerSample = 8;
> 
>  
> 
> Once sound is aquired by the mic, I send it to Speex in a Char buffer.
> It looks something like this:
> 
>  
> 
> Encode(char* inBuffer, DWORD bufferLength)
> 
> ...
> 
> float* input = new float[frameSize];
> 
> ZeroMemory(input, frameSize);
> 
> ...
> 
> for(    )
> 
> {
> 
> input[..] = inBuffer[..];
> 
> }
> 
> ...
> 
> speex_encode(enc_state, input, &bits);
> 
> int bytesWritten = speex_bits_nbytes(&bits);
> 
> speex_bits_write(&bits, encBuffer, bytesWritten);
> 
>  
> 
>  
> 
>  
> 
> Then, my decoding routine accepts the char buffer that was encoded with
> Speex:
> 
>  
> 
> Decode(char* encBuffer, DWORD bufferLength)
> 
> ...
> 
> float* output = new float[frameSize];
> 
> ...
> 
> speex_bits_read_from(&bits, encBuffer + offset, bytesToRead);
> 
> speex_decode(dec_state, &bits, output);
> 
>  
> 
> char* outBuffer=...
> 
> for(UINT i = 0; i < frameSize; i++)
> 
> {
> 
> outBuffer[retValIndex] = output[i];
> 
> retValIndex++;
> 
> }
> 
>  
> 
> When I try to play outBuffer with waveOut, I can hear the voice
> “somewhere far”, but there is a lot of distortion noise. Any help would
> be greatly appreciated!!!
> 
>  
> 
> Thank you,
> 
>  
> 
> Evgueni Tsygankov
> 
> www.sqlanswers.com <http://www.sqlanswers.com/>
> 
>  
> 
> 
> ------------------------------------------------------------------------
> 
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