Right then, this is taxing my poor brain.....

I've written a simple mp3 player using MAD and JACK in C. This works a treat. I now want to encapsulate this into a class and stick in a Qt application. I've copied the code into a class structure and I'm trying to compile it. JACK uses a callback mechanism to send data to the sound system. Under C i used 4 functions to assign callbacks to functions. I've added these functions into the class. The class definition looks like this:

Code:

class MP3Play : public QWidget
{
	public:
		MP3Play( QWidget *parent=0, const char *name=0 );
		int Load(QString);
	private:
		const char	*ProgName;
		int 		default_driver;
		char 		*buffer;
		int 		buf_size;
		int 		sample;
		int 		iCount;
		SNDFILE		*sf;
		
		//typedef double sample_t;
		typedef jack_default_audio_sample_t sample_t;
		
		struct mad_stream	Stream;
		struct mad_frame	Frame;
		struct mad_synth	Synth;
		mad_timer_t		Timer;
		unsigned char		InputBuffer[INPUT_BUFFER_SIZE+MAD_BUFFER_GUARD], OutputBuffer[OUTPUT_BUFFER_SIZE], *OutputPtr, *GuardPtr;
		const unsigned char	*OutputBufferEnd;
		
		int			Status, i, iSpill, bdecode;
		unsigned long		FrameCount;
		bstdfile_t		*BstdFile;
		FILE 			*InputFp;
		
		sample_t		spill_l[1152];
		sample_t		spill_r[1152];
		
		FILE			*mp3file;
		jack_client_t 		*client;
		const char 		**ports;
		
		/*Our output port*/
		jack_port_t *output_port_l,*output_port_r;
		
		/*The current sample rate*/
		jack_nframes_t sr;

		int  process (jack_nframes_t, void *);
		int  srate (jack_nframes_t, void *);
		void error (const char *);
		void jack_shutdown (void *);
};


The JACK specific initalisation code looks this:
Code:

	jack_set_error_function (MP3Play::error);
	jack_set_process_callback (client, MP3Play::process, 0);
	jack_set_sample_rate_callback (client, MP3Play::srate, 0);
	jack_on_shutdown (client, MP3Play::jack_shutdown, 0);


The compiler errors look like this:
Code:

mp3playback.cpp: In member function `int MP3Play::Load(QString)':
mp3playback.cpp:118: error: no matches converting function `error' to type `
   void (*)(const char*)'
mp3playback.cpp:76: error: candidates are: void MP3Play::error(const char*)
mp3playback.cpp:126: error: no matches converting function `process' to type `
   int (*)(unsigned int, void*)'
mp3playback.cpp:74: error: candidates are: int MP3Play::process(unsigned int,
   void*)
mp3playback.cpp:127: error: no matches converting function `srate' to type `int
   (*)(unsigned int, void*)'
mp3playback.cpp:75: error: candidates are: int MP3Play::srate(unsigned int,
   void*)
mp3playback.cpp:128: error: no matches converting function `jack_shutdown' to
   type `void (*)(void*)'
mp3playback.cpp:77: error: candidates are: void MP3Play::jack_shutdown(void*)


All I want is to completely encapsulate the code into a class, so I can initialise as many players I need.

Any pointers? (Pardon the pun)
_________________________
Cheers,

Andy M