[Speex-dev] using speex in C#

[yaseminyilmaz]

Hi SAITAMA Taro,

I have been using speex-1.2beta1 dll in our voice application written with
C#. In order to use Speex correctly firstly I advice to you examination
speexenc and speexdec projects.

I have used unsafe code and fixed statements in C#. I have added following
method to library and I used that instead of speex_encoder_init simply.

void *speex_encoder_init_new(int modeID)
{
	const SpeexMode *mode;
	mode = speex_lib_get_mode(modeID);
	return mode->enc_init(mode);
}

Maybe following codes that I have been using in a class can help you.
/* structs */
public struct SpeexBits 
{
	char *chars;		/* "raw" data */
	int   nbBits;		/* Total number of bits stored in the
stream*/
	int   charPtr;		/* Position of the byte "cursor" */
	int   bitPtr;		/* Position of the bit "cursor" within the
current char */
	int   owner;		/* Does the struct "own" the "raw" buffer
(member "chars") */
	int   overflow;		/* Set to one if we try to read past the
valid data */
	int   buf_size;		/* Allocated size for buffer */
	int   reserved1;	/* Reserved for future use */
	void *reserved2;	/* Reserved for future use */
}
...

/* EXPORTED ENCODER METHODS */
[DllImport("libspeex.dll")]
	public static extern void *speex_encoder_init_new(int modeID);
[DllImport("libspeex.dll")]
	public static extern int speex_encoder_ctl(void *state, int request,
void *ptr);
/* default this function doesn't exist but same job is done
speex_encoder_ctl function too. */
[DllImport("libspeex.dll")]
	public static extern int speex_encoder_settings(void *state, int
complexity, int samplingrate, int quality, int bitrate);
[DllImport("libspeex.dll")]
	public static extern int speex_encode_int(void *state, short *input,
SpeexBits *bits);	// IntPtr
...
/* EXPORTED BIT-OPERATION METHODS */
[DllImport("libspeex.dll")]
	public static extern void speex_bits_init(SpeexBits *bits);
[DllImport("libspeex.dll")]
	public static extern int speex_bits_write(SpeexBits *bits, IntPtr
bytes, int max_len);	// char *
...

/* some global variables */
int frame_size;	
void *enc_state;
SpeexBits enc_bits;
short[] input_frame;
...

/* from Constructor */
...
enc_bits = new SpeexBits();
enc_state = speex_encoder_init_new(0);
speex_encoder_settings(enc_state, 3, 8000, 10, 11000);
fixed (int *fSize = &frame_size)
{
	speex_encoder_ctl(enc_state, SPEEX_GET_FRAME_SIZE, fSize);
}
fixed (SpeexBits *bitsAdd = &enc_bits)
{
	speex_bits_init(bitsAdd);
}
/* MAX_FRAME_SIZE is a constant and is 2000 */
input_frame = new short[MAX_FRAME_SIZE];

/* From Encode Function */
/* after voice data capture */
fixed (short *inputAdd = input_frame)
	fixed (SpeexBits *bitsAdd = &enc_bits)
	{
		speex_encode_int(enc_state, inputAdd, bitsAdd);
		encodedDataSize = speex_bits_write(bitsAdd, enc_outputAdd,
MAX_FRAME_BYTES);
	}
fixed (SpeexBits *bitsAdd = &enc_bits)
{
	speex_bits_reset(bitsAdd);
}



-----Original Message-----
From: speex-dev-request at xiph.org [mailto:speex-dev-request at xiph.org] 
Sent: Thursday, December 28, 2006 10:00 PM
To: speex-dev at xiph.org
Subject: Speex-dev Digest, Vol 31, Issue 29

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Today's Topics:

   1. using speex in C# (SAITAMA Taro)


----------------------------------------------------------------------

Message: 1
Date: Thu, 28 Dec 2006 17:09:08 +0900
From: SAITAMA Taro <game72 at gmail.com>
Subject: [Speex-dev] using speex in C#
To: speex-dev at xiph.org
Message-ID: <20061228170814.9F7E.GAME72 at gmail.com>
Content-Type: text/plain; charset="US-ASCII"

Hi,

I have read the message below,
http://lists.xiph.org/pipermail/speex-dev/2006-October/004924.html
and try to use P/Invoke to use speex in C#.

This is a part of my code.

	[StructLayout(LayoutKind.Sequential)]
	public struct SpeexBits {
		IntPtr chars;			// "raw" data
		int nbBits;			// Total number of bits
stored in the stream
		int charPtr;			// Position of the byte
"cursor"
		int bitPtr;			// Position of the bit
"cursor" within the current char
		int owner;			// Does the struct "own" the
"raw" buffer (member "chars")
		int overflow;			// Set to one if we try to
read past the valid data
		int buf_size;			// Allocated size for buffer
		int reserved1;			// Reserved for future use
		IntPtr reserved2;		// Reserved for future use
	}

	[DllImport("libspeex.dll")]
	public static extern IntPtr speex_lib_get_mode(int mode);	//
Obtain one of the modes available

	[DllImport("libspeex.dll")]
	public static extern IntPtr speex_encoder_init(ref SpeexMode mode);

	[DllImport("libspeex.dll")]
	public static extern void speex_bits_init(ref SpeexBits bits);

	[DllImport("libspeex.dll")]
	public static extern int speex_encode_int(IntPtr state, Int16[] in_,
ref SpeexBits bits);

	SpeexBits bits = new SpeexBits();
	SpeexMode mode =
(SpeexMode)Marshal.PtrToStructure(Speex.speex_lib_get_mode(1),
typeof(SpeexMode));
	Speex.speex_bits_init(ref bits);
	IntPtr enc_state = Speex.speex_encoder_init(ref mode);

	Int16[] CaptureData = null;
	(CaptureData receives data recorded from mic...)
	CaptureData = (Int16[])dsCapBuffer.Read(NextCaptureOffset,
typeof(Int16), LockFlag.None, LockSize);

	Speex.speex_bits_reset(ref bits);
	Speex.speex_encode_int(enc_state, CaptureData, ref bits);	//
at this point, System.AccessViolationException occurs

Whould anyone tell me what wrong about my code?
Please help me.

Regards

Kaihong


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