audio_hp.c

用JAVA写的MP3,MP2,MP1解码源代码

#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>

#include "audio.h"

#include <sys/audio.h>

int audio_open(struct audio_info_struct *ai)
{
  struct audio_describe ades;
  struct audio_gain again;
  int i,audio;

  ai->fn = open("/dev/audio",O_RDWR);

  if(ai->fn < 0)
    return -1;


  ioctl(ai->fn,AUDIO_DESCRIBE,&ades);

  if(ai->gain != -1)
  {
     if(ai->gain > ades.max_transmit_gain)
     {
       fprintf(stderr,"your gainvalue was to high -> set to maximum.\n");
       ai->gain = ades.max_transmit_gain;
     }
     if(ai->gain < ades.min_transmit_gain)
     {
       fprintf(stderr,"your gainvalue was to low -> set to minimum.\n");
       ai->gain = ades.min_transmit_gain;
     }
     again.channel_mask = AUDIO_CHANNEL_0 | AUDIO_CHANNEL_1;
     ioctl(ai->fn,AUDIO_GET_GAINS,&again);
     again.cgain[0].transmit_gain = ai->gain;
     again.cgain[1].transmit_gain = ai->gain;
     again.channel_mask = AUDIO_CHANNEL_0 | AUDIO_CHANNEL_1;
     ioctl(ai->fn,AUDIO_SET_GAINS,&again);
  }
  
  if(ai->output != -1)
  {
     if(ai->output == AUDIO_OUT_INTERNAL_SPEAKER)
       ioctl(ai->fn,AUDIO_SET_OUTPUT,AUDIO_OUT_SPEAKER);
     else if(ai->output == AUDIO_OUT_HEADPHONES)
       ioctl(ai->fn,AUDIO_SET_OUTPUT,AUDIO_OUT_HEADPHONE);
     else if(ai->output == AUDIO_OUT_LINE_OUT)
       ioctl(ai->fn,AUDIO_SET_OUTPUT,AUDIO_OUT_LINE);
  }
  
  if(ai->rate == -1)
    ai->rate = 44100;

  for(i=0;i<ades.nrates;i++)
  {
    if(ai->rate == ades.sample_rate[i])
      break;
  }
  if(i == ades.nrates)
  {
    fprintf(stderr,"Can't set sample-rate to %ld.\n",ai->rate);
    i = 0;
  }

  if(audio_reset_parameters(ai) < 0)
    return -1;
 
  return ai->fn;
}

int audio_reset_parameters(struct audio_info_struct *ai)
{
  int ret;
  ret = audio_set_format(ai);
  if(ret >= 0)
    ret = audio_set_channels(ai);
  if(ret >= 0)
    ret = audio_set_rate(ai);
  return ret;
}

int audio_rate_best_match(struct audio_info_struct *ai)
{
  return 0;
}

int audio_set_rate(struct audio_info_struct *ai)
{
  if(ai->rate >= 0)
    return ioctl(ai->fn,AUDIO_SET_SAMPLE_RATE,ai->rate);
  return 0;
}

int audio_set_channels(struct audio_info_struct *ai)
{
  return ioctl(ai->fn,AUDIO_SET_CHANNELS,ai->channels);
}

int audio_set_format(struct audio_info_struct *ai)
{
  int fmt;

  switch(ai->format) {
    case -1:
    case AUDIO_FORMAT_SIGNED_16:
    default: 
      fmt = AUDIO_FORMAT_LINEAR16BIT;
      break;
    case AUDIO_FORMAT_UNSIGNED_8:
      fprintf(stderr,"unsigned 8 bit linear not supported\n");
      return -1;
    case AUDIO_FORMAT_SIGNED_8:
      fprintf(stderr,"signed 8 bit linear not supported\n");
      return -1;
    case AUDIO_FORMAT_ALAW_8:
      fmt = AUDIO_FORMAT_ALAW;
      break;
    case AUDIO_FORMAT_ULAW_8:
      fmt = AUDIO_FORMAT_ULAW;
      break;
  }
  return ioctl(ai->fn,AUDIO_SET_DATA_FORMAT,fmt);
}

int audio_get_formats(struct audio_info_struct *ai)
{
  return AUDIO_FORMAT_SIGNED_16;
}


int audio_play_samples(struct audio_info_struct *ai,unsigned char *buf,int len)
{
  return write(ai->fn,buf,len);
}

int audio_close(struct audio_info_struct *ai)
{
  close (ai->fn);
  return 0;
}