mp12libce.cpp

一个播放器 使用了evc 大家可以参考下 哦

}

/*
static __inline
signed long linear_dither(unsigned int bits, mad_fixed_t sample,
			  mad_fixed_t *error)
{
  mad_fixed_t quantized, check;

  sample += *error;

  quantized = sample;
  check = (sample >> MAD_F_FRACBITS) + 1;
  if (check & ~1) {
    if (sample >= MAD_F_ONE) {
      quantized = MAD_F_ONE - 1;
    }
    else if (sample < -MAD_F_ONE) {
      quantized = -MAD_F_ONE;
    }
  }

  quantized &= ~((1L << (MAD_F_FRACBITS + 1 - bits)) - 1);

  *error = sample - quantized;

  return quantized >> (MAD_F_FRACBITS + 1 - bits);
}
*/
static inline
signed long linear_dither(unsigned int bits, mad_fixed_t sample,
			  mad_fixed_t *error, unsigned long *clipped,
			  mad_fixed_t *clipping)
{
  mad_fixed_t quantized, check;

  /* dither */
  sample += *error;

  /* clip */
  quantized = sample;
  check = (sample >> MAD_F_FRACBITS) + 1;
  if (check & ~1) {
    if (sample >= MAD_F_ONE) {
      quantized = MAD_F_ONE - 1;
      ++*clipped;
      if (sample - quantized > *clipping &&
	  mad_f_abs(*error) < (MAD_F_ONE >> (MAD_F_FRACBITS + 1 - bits)))
	*clipping = sample - quantized;
    }
    else if (sample < -MAD_F_ONE) {
      quantized = -MAD_F_ONE;
      ++*clipped;
      if (quantized - sample > *clipping &&
	  mad_f_abs(*error) < (MAD_F_ONE >> (MAD_F_FRACBITS + 1 - bits)))
	*clipping = quantized - sample;
    }
  }

  /* quantize */
  quantized &= ~((1L << (MAD_F_FRACBITS + 1 - bits)) - 1);

  /* error */
  *error = sample - quantized;

  /* scale */
  return quantized >> (MAD_F_FRACBITS + 1 - bits);
}

static
unsigned int pack_pcm(unsigned char *data, unsigned int nsamples,
		      mad_fixed_t const *left, mad_fixed_t const *right,
		      int resolution, unsigned long *clipped,
			  mad_fixed_t *clipping)
{
  static mad_fixed_t left_err, right_err;
  unsigned char const *start;
  register signed long sample0, sample1;
  int effective, bytes;

  start     = data;
//  effective = resolution;//(resolution > 24) ? 24 : resolution;
//  bytes     = resolution >>3;

  if (right) {  /* stereo */
    while (nsamples--) {
      sample0 = linear_dither(16, *left++, &left_err, clipped,clipping);
      sample1 = linear_dither(16, *right++, &right_err, clipped,clipping);

	data[0] = sample0 >>  0;
	data[1] = sample0 >>  8;
	data[2] = sample1 >>  0;
	data[3] = sample1 >>  8;

      data += 4; //bytes << 1;
    }
  }
  else {  /* mono */
    while (nsamples--)
	{
      sample0 = linear_dither(16, *left++, &left_err, clipped,clipping);

		data[1] = sample0 >>  8;
		data[0] = sample0 >>  0;
		data += 2;
    }
  }

  return data - start;
}

// This is an example of an exported function.
MP12LIBCE_API void Init(int Equalizer,char* eq)
{
	if (begin)
	{
	  mad_stream_init(&stream);
	  mad_frame_init(&frame);
	 mad_synth_init(&synth);
	 currentpos=0;
	 framepos=0;
		begin=1;
		seeking=1;
	}
	equalizer=Equalizer;
	clipped=0;
	attenuation=MAD_F_ONE;
	if (eq)
	{
		set_eq(1,eq,eq[10]);
	}

}
// This is an example of an exported function.
MP12LIBCE_API void Exit(void)
{
  mad_frame_finish(&frame);
  mad_stream_finish(&stream);
  mad_synth_finish(&synth);
	begin=1;
}
MP12LIBCE_API void SeekStart()
{
	Exit();
}

MP12LIBCE_API void SeekEnd()
{
	Init(equalizer,0);
}

//static char buffer[40000];
MP12LIBCE_API int GetHeaderInfo(unsigned char * inbuff, int insize, int* Freq, int* ch, int* BitRate)
{
		int tempcpos,tempframepos;
  	  currentpos+=framepos;
   	  mad_stream_buffer(&stream, (const unsigned char *)inbuff, insize);
	  while (mad_frame_decode(&frame, &stream) == -1)
	  {
		if (stream.error == MAD_ERROR_BUFLEN)
		{

			framepos=(int)(stream.this_frame-stream.buffer);
			if (stream.bufend - stream.this_frame==insize)
				return 32768;
			else if (stream.bufend - stream.this_frame)
				return stream.bufend - stream.this_frame;
			else
				return 32768;
		}
	  }
	  if (!*Freq)
	  {
		*Freq=frame.header.samplerate;
		  resample=0;
	  }
	  else
	  {
		  resample=1;
		  resample_rate=*Freq;
	  }
		framepos=(int)(stream.this_frame-stream.buffer);
		tempcpos=currentpos;
		tempframepos=framepos;
	  *BitRate=frame.header.bitrate;
	  *ch=(frame.header.mode > 0) ? 2 : 1;
		Exit();
		Init(equalizer,0);
				currentpos=tempcpos;
		framepos=tempframepos;

	  return 0;
}

MP12LIBCE_API int DecompressAudio(unsigned char * inbuff, int insize, char *outmemory, int outmemsize, int *done, int* inputpos)
{

    mad_fixed_t const *ch1, *ch2;
    mad_fixed_t *rch1, *rch2;
	resample_state rs;
	int resolution=16;
	if (inbuff)
	{
//	    int remainder = stream.bufend - stream.this_frame;
//		memcpy(buffer, stream.this_frame, remainder);
//		memcpy(buffer+remainder,inbuff,insize+remainder);
		mad_stream_buffer(&stream, (const unsigned char *)inbuff, insize);
		currentpos+=framepos;
		begin=0;
	}
	else if (begin)
	{
		*done=0;
		return 1;
	}
	int nch;
	int output_length=0;
	//long clipping=0,clipped=0;
	mad_fixed_t clipping=0;
	int err=mad_frame_decode(&frame, &stream);
	if (err==-1)
	{
		if (stream.error == MAD_ERROR_BUFLEN)
		{

			framepos=(int)(stream.this_frame-stream.buffer);
			*inputpos=currentpos+framepos;
			*done=0;
			if (stream.bufend - stream.this_frame==insize)
				return 32768;
			else if (stream.bufend - stream.this_frame)
				return stream.bufend - stream.this_frame;
			else
				return 32768;
//				retval=stream.bufend - stream.this_frame+1;			
		}
		else if (stream.error == MAD_ERROR_BADBITALLOC)
		{
			stream.sync=0;

			framepos=(int)(stream.this_frame-stream.buffer);
			*inputpos=currentpos+framepos;
			*done=0;
			return 32768;
		}
		else //if((stream.error ==MAD_ERROR_LOSTSYNC||(stream.error==MAD_ERROR_BADDATAPTR)))
		{
			stream.sync=0;
			framepos=(int)(stream.this_frame-stream.buffer);
			*inputpos=currentpos+framepos;
			*done=0;
			return 0;
		}
//		else
//		{
//			return -1;
//		}
	}
	seeking=0;
	framepos=(int)(stream.this_frame-stream.buffer);
	*inputpos=currentpos+framepos;
	if (equalizer)
	{
		attenuate_filter(&frame,attenuation);
		equalizer_filter(&frame,eqfactor);
	}
	mad_synth_frame(&synth,&frame);
	nch= synth.pcm.channels;
	ch1 = synth.pcm.samples[0];
	ch2 = synth.pcm.samples[1];
	if (resample)
	{
		int t;
		rch1=(long*)malloc(sizeof(ch1[0])*(synth.pcm.length));
		resample_init(&rs,synth.pcm.samplerate,resample_rate);
		t=resample_block(&rs,synth.pcm.length,ch1,rch1);
		if (nch == 1)
		{
			rch2 = 0;
		}
		else
		{
			rch2=(long*)malloc(sizeof(ch1[1])*(synth.pcm.length));
			resample_init(&rs,48000,44100);
			t=resample_block(&rs,synth.pcm.length,ch2,rch2);
		}
		synth.pcm.length=t;
		*done=pack_pcm(((unsigned char *)outmemory),
			 synth.pcm.length, rch1, rch2, resolution, &clipped,&clipping);
		free(rch1);
		if (rch2)
			free(rch2);
		if (equalizer)
		{
			attenuation =
			  mad_f_tofixed(mad_f_todouble(attenuation) /
					mad_f_todouble(MAD_F_ONE +
							   mad_f_mul(clipping,
								 conf_attsensitivity)));
		}
		return 0;    
	}

	if (nch == 1)
		ch2 = 0;
	*done=pack_pcm(((unsigned char *)outmemory),
		 synth.pcm.length, ch1, ch2, resolution, &clipped,&clipping);
	if (equalizer)
	{
		attenuation =
		  mad_f_tofixed(mad_f_todouble(attenuation) /
				mad_f_todouble(MAD_F_ONE +
						   mad_f_mul(clipping,
							 conf_attsensitivity)));
	}
	return 0;    
}
// This is the constructor of a class that has been exported.
// see MP12LibCE.h for the class definition
CMP12LibCE::CMP12LibCE()
{ 
	return; 
}