af.c

自己移植的linux下的流媒体播放器原代码,支持mms协议,支持ftp和http协议.

  // Check if this is the first call
  if(!s->first){
    // Add all filters in the list (if there are any)
    if(!s->cfg.list){      // To make automatic format conversion work
      if(!af_append(s,s->first,"dummy")) 
	return -1; 
    }
    else{
      while(s->cfg.list[i]){
	if(!af_append(s,s->last,s->cfg.list[i++]))
	  return -1;
      }
    }
  }

  // Init filters 
  if(AF_OK != af_reinit(s,s->first))
    return -1;

  // If force_output isn't set do not compensate for output format
  if(!force_output){
    memcpy(&s->output, s->last->data, sizeof(af_data_t));
    return 0;
  }

  // Check output format
  if((AF_INIT_TYPE_MASK & s->cfg.force) != AF_INIT_FORCE){
    af_instance_t* af = NULL; // New filter
    // Check output frequency if not OK fix with resample
    if(s->last->data->rate!=s->output.rate){
      // try to find a filter that can change samplrate
      af = af_control_any_rev(s, AF_CONTROL_RESAMPLE_RATE | AF_CONTROL_SET,
               &(s->output.rate));
      if (!af) {
        char *resampler = "resample";
#ifdef USE_LIBAVCODEC
        if ((AF_INIT_TYPE_MASK & s->cfg.force) == AF_INIT_SLOW)
          resampler = "lavcresample";
#endif
	if((AF_INIT_TYPE_MASK & s->cfg.force) == AF_INIT_SLOW){
	  if(!strcmp(s->first->info->name,"format"))
	    af = af_append(s,s->first,resampler);
	  else
	    af = af_prepend(s,s->first,resampler);
	}		
	else{
	  if(!strcmp(s->last->info->name,"format"))
	    af = af_prepend(s,s->last,resampler);
	  else
	    af = af_append(s,s->last,resampler);
	}
      // Init the new filter
      if(!af || (AF_OK != af->control(af,AF_CONTROL_RESAMPLE_RATE | AF_CONTROL_SET,
				      &(s->output.rate))))
	return -1;
      // Use lin int if the user wants fast
      if ((AF_INIT_TYPE_MASK & s->cfg.force) == AF_INIT_FAST) {
        char args[32];
	sprintf(args, "%d", s->output.rate);
#ifdef USE_LIBAVCODEC
	if (strcmp(resampler, "lavcresample") == 0)
	  strcat(args, ":1");
	else
#endif
	strcat(args, ":0:0");
	af->control(af, AF_CONTROL_COMMAND_LINE, args);
      }
      }
      if(AF_OK != af_reinit(s,af))
      	return -1;
    }	
      
    // Check number of output channels fix if not OK
    // If needed always inserted last -> easy to screw up other filters
    if(s->last->data->nch!=s->output.nch){
      if(!strcmp(s->last->info->name,"format"))
	af = af_prepend(s,s->last,"channels");
      else
	af = af_append(s,s->last,"channels");
      // Init the new filter
      if(!af || (AF_OK != af->control(af,AF_CONTROL_CHANNELS,&(s->output.nch))))
	return -1;
      if(AF_OK != af_reinit(s,af))
	return -1;
    }
    
    // Check output format fix if not OK
    if(s->last->data->format != s->output.format){
      if(strcmp(s->last->info->name,"format"))
	af = af_append(s,s->last,"format");
      else
	af = s->last;
      // Init the new filter
      s->output.format |= af_bits2fmt(s->output.bps*8);
      if(!af || (AF_OK != af->control(af,AF_CONTROL_FORMAT_FMT,&(s->output.format))))
	return -1;
      if(AF_OK != af_reinit(s,af))
	return -1;
    }

    // Re init again just in case
    if(AF_OK != af_reinit(s,s->first))
      return -1;

    if((s->last->data->format != s->output.format) || 
       (s->last->data->nch    != s->output.nch)    || 
       (s->last->data->rate   != s->output.rate))  {
      // Something is stuffed audio out will not work 
      af_msg(AF_MSG_ERROR,"[libaf] Unable to setup filter system can not" 
	     " meet sound-card demands, please send bugreport. \n");
      af_uninit(s);
      return -1;
    }
  }
  return 0;
}

/* Add filter during execution. This function adds the filter "name"
   to the stream s. The filter will be inserted somewhere nice in the
   list of filters. The return value is a pointer to the new filter,
   If the filter couldn't be added the return value is NULL. */
af_instance_t* af_add(af_stream_t* s, char* name){
  af_instance_t* new;
  // Sanity check
  if(!s || !s->first || !name)
    return NULL;
  // Insert the filter somwhere nice
  if(!strcmp(s->first->info->name,"format"))
    new = af_append(s, s->first, name);
  else
    new = af_prepend(s, s->first, name);
  if(!new)
    return NULL;

  // Reinitalize the filter list
  if(AF_OK != af_reinit(s, s->first)){
    free(new);
    return NULL;
  }
  return new;
}

// Filter data chunk through the filters in the list
af_data_t* af_play(af_stream_t* s, af_data_t* data)
{
  af_instance_t* af=s->first; 
  // Iterate through all filters 
  do{
    data=af->play(af,data);
    af=af->next;
  }while(af);
  return data;
}

/* Helper function used to calculate the exact buffer length needed
   when buffers are resized. The returned length is >= than what is
   needed */
inline int af_lencalc(frac_t mul, af_data_t* d){
  register int t = d->bps*d->nch;
  return t*(((d->len/t)*mul.n)/mul.d + 1);
}

/* Calculate how long the output from the filters will be given the
   input length "len". The calculated length is >= the actual
   length. */
int af_outputlen(af_stream_t* s, int len)
{
  int t = s->input.bps*s->input.nch;
  af_instance_t* af=s->first; 
  frac_t mul = {1,1};
  // Iterate through all filters 
  do{
    af_frac_mul(&mul, &af->mul);
    af=af->next;
  }while(af);
  return t * (((len/t)*mul.n + 1)/mul.d);
}

/* Calculate how long the input to the filters should be to produce a
   certain output length, i.e. the return value of this function is
   the input length required to produce the output length "len". The
   calculated length is <= the actual length */
int af_inputlen(af_stream_t* s, int len)
{
  int t = s->input.bps*s->input.nch;
  af_instance_t* af=s->first; 
  frac_t mul = {1,1};
  // Iterate through all filters 
  do{
    af_frac_mul(&mul, &af->mul);
    af=af->next;
  }while(af);
  return t * (((len/t) * mul.d - 1)/mul.n);
}

/* Calculate how long the input IN to the filters should be to produce
   a certain output length OUT but with the following three constraints:
   1. IN <= max_insize, where max_insize is the maximum possible input
      block length
   2. OUT <= max_outsize, where max_outsize is the maximum possible
      output block length
   3. If possible OUT >= len. 
   Return -1 in case of error */ 
int af_calc_insize_constrained(af_stream_t* s, int len,
			       int max_outsize,int max_insize)
{
  int t   = s->input.bps*s->input.nch;
  int in  = 0;
  int out = 0;
  af_instance_t* af=s->first; 
  frac_t mul = {1,1};
  // Iterate through all filters and calculate total multiplication factor
  do{
    af_frac_mul(&mul, &af->mul);
    af=af->next;
  }while(af);
  // Sanity check 
  if(!mul.n || !mul.d) 
    return -1;

  in = t * (((len/t) * mul.d - 1)/mul.n);
  
  if(in>max_insize) in=t*(max_insize/t);

  // Try to meet constraint nr 3. 
  while((out=t * (((in/t+1)*mul.n - 1)/mul.d)) <= max_outsize && in<=max_insize){
    if( (t * (((in/t)*mul.n))/mul.d) >= len) return in;
    in+=t;
  }
  
  // Could no meet constraint nr 3.
  while(out > max_outsize || in > max_insize){
    in-=t;
    if(in<t) return -1; // Input parameters are probably incorrect
    out = t * (((in/t)*mul.n + 1)/mul.d);
  }
  return in;
}

/* Calculate the total delay [ms] caused by the filters */
double af_calc_delay(af_stream_t* s)
{
  af_instance_t* af=s->first; 
  register double delay = 0.0;
  // Iterate through all filters 
  while(af){
    delay += af->delay;
    af=af->next;
  }
  return delay;
}

/* Helper function called by the macro with the same name this
   function should not be called directly */
inline int af_resize_local_buffer(af_instance_t* af, af_data_t* data)
{
  // Calculate new length
  register int len = af_lencalc(af->mul,data);
  af_msg(AF_MSG_VERBOSE,"[libaf] Reallocating memory in module %s, " 
	 "old len = %i, new len = %i\n",af->info->name,af->data->len,len);
  // If there is a buffer free it
  if(af->data->audio) 
    free(af->data->audio);
  // Create new buffer and check that it is OK
  af->data->audio = malloc(len);
  if(!af->data->audio){
    af_msg(AF_MSG_FATAL,"[libaf] Could not allocate memory \n");
    return AF_ERROR;
  }
  af->data->len=len;
  return AF_OK;
}

/**
 * \brief send control to all filters, starting with the last, until
 *        one responds with AF_OK
 * \return The instance that accepted the command or NULL if none did.
 */
af_instance_t *af_control_any_rev (af_stream_t* s, int cmd, void* arg) {
  int res = AF_UNKNOWN;
  af_instance_t* filt = s->last;
  while (filt) {
    res = filt->control(filt, cmd, arg);
    if (res == AF_OK)
      return filt;
    filt = filt->prev;
  }
  return NULL;
}

/**
 * \brief calculate greatest common divisior of a and b.
 *   Extended for negative and 0 values. If both are 0 the result is 1.
 *   The sign of the result will be so that it has the same sign as b.
 */
int af_gcd(register int a, register int b) {
  int b_org = b;
  while (b != 0) {
    a %= b;
    if (a == 0)
      break;
    b %= a;
  }
  // the result is either in a or b. As the other one is 0 just add them.
  a += b;
  if (!a)
    return 1;
  if (a * b_org < 0)
    return -a;
  return a;
}

/**
 * \brief cancel down a fraction f
 */
void af_frac_cancel(frac_t *f) {
  int gcd = af_gcd(f->n, f->d);
  f->n /= gcd;
  f->d /= gcd;
}

/**
 * \brief multiply out by in and store result in out.
 *        the resulting fraction wil be cancelled down
 *        if in and out were.
 */
void af_frac_mul(frac_t *out, const frac_t *in) {
  int gcd1 = af_gcd(out->n, in->d);
  int gcd2 = af_gcd(in->n, out->d);
  out->n = (out->n / gcd1) * (in->n / gcd2);
  out->d = (out->d / gcd2) * (in->d / gcd1);
}

void af_help (void) {
  int i = 0;
  af_msg(AF_MSG_INFO, "Available audio filters:\n");
  while (filter_list[i]) {
    if (filter_list[i]->comment && filter_list[i]->comment[0])
      af_msg(AF_MSG_INFO, "  %-15s: %s (%s)\n", filter_list[i]->name, filter_list[i]->info, filter_list[i]->comment);
    else
      af_msg(AF_MSG_INFO, "  %-15s: %s\n", filter_list[i]->name, filter_list[i]->info);
    i++;
  }
}

void af_fix_parameters(af_data_t *data)
{
    data->bps = af_fmt2bits(data->format)/8;
}