wave.c

AAC音频解码算法程序

#include <stdio.h>
#include <windows.h>
#include "portableio.h"

#include "error.h"
#include "wave.h"


BOOL checkString(FILE *file,char *string)
{
    char temp[1024];
    unsigned int  length = strlen(string);
    if(fread(temp,1,length,file)!=length) ERROROUT("Premature EOF in input !?!");
    temp[length] = (char)0;
	return !strcmp(temp,string);
}

void wave_close(FILE *wavefile)
{
    fclose(wavefile);
}

FILE* wave_open(const char *path, WAVE_INFO *wave_info)//wave_open(FileNames[i], &wave_info);
{
 //   static char    *channel_mappings[] = {NULL,"mono","stereo"};
    unsigned short  wFormatTag;
    unsigned long   dAvgBytesPerSec;
    unsigned short  wBlockAlign;
    long            filesize;
    long            header_size;
	FILE *          wavefile;

    if((wavefile = fopen(path,"rb")) == NULL) 
		ERROROUT("Unable to open wave file");

    if(!checkString(wavefile,"RIFF")) ERROROUT("Input not a MS-RIFF file");
    filesize = Read32BitsLowHigh(wavefile); /* complete wave chunk size */
    printf("Microsoft RIFF, ");

    if(!checkString(wavefile,"WAVE")) ERROROUT("Input not WAVE audio");
    printf("WAVE audio, ");

/* WAVE FMT format chunk */
    if(!checkString(wavefile,"fmt "))  ERROROUT("Can't find format chunk");
/* my total header size calculations don't work, so this is bogus... */
    header_size = Read32BitsLowHigh(wavefile); /* chunk size */

    wFormatTag = Read16BitsLowHigh(wavefile);
    if(wFormatTag!=0x0001) ERROROUT("Not PCM Signal");
    wave_info->format = WAVE_RIFF_PCM;

    wave_info->channels      = Read16BitsLowHigh(wavefile);
    wave_info->samplerate    = Read32BitsLowHigh(wavefile);
    dAvgBytesPerSec        = Read32BitsLowHigh(wavefile);
    wBlockAlign            = Read16BitsLowHigh(wavefile);

/* PCM specific */
  //  if(waveinfo.channels>2) ERROR("More than 2 channels\n");
/*   printf("PCM, %s %ldHz ", 
           channel_mappings[config.wave.channels], waveinfo.samplerate);*/
    wave_info->pcmbitwidth       = Read16BitsLowHigh(wavefile);
    if(wave_info->pcmbitwidth!=16) ERROROUT("NOT 16 Bit !!!\n");
    printf("%dbit, ", wave_info->pcmbitwidth);

    if(!checkString(wavefile,"data")) ERROROUT("Can't find data chunk");

    header_size = ftell(wavefile);
    fseek(wavefile, 0, SEEK_END);
    filesize = ftell(wavefile);
    fseek(wavefile, header_size, SEEK_SET);

    wave_info->samples = (filesize-header_size)/(2*wave_info->channels);
  /* config.wave.length = config.wave.total_samples/config.wave.samplerate;
    printf("Length: %2ld:%2ld:%2ld\n", (config.wave.length/3600), 
                                       (config.wave.length/60)%60,
                                       (config.wave.length%60)); */
    return wavefile;
}

static int read_samples(short *sample_buffer,
                        int    frame_size,FILE * wavefile,WAVE_INFO wave_info)
{
    int samples_read;

    switch(wave_info.format)
    {
        default          :
            ERROROUT("[read_samples], wave filetype not supported");

        case WAVE_RIFF_PCM :
            samples_read = fread(sample_buffer,sizeof(short),frame_size,wavefile);
    
            /* Microsoft PCM Samples are little-endian, */
            /* we must swap if this is a big-endian machine */

   /*        if(config.byte_order==order_bigEndian) 
               SwapBytesInWords(sample_buffer,samples_read);*/

           if(samples_read<frame_size && samples_read>0) 
           { /* Pad sample with zero's */
               while(samples_read<frame_size) sample_buffer[samples_read++] = 0;
           }

           break;
    }
    return samples_read;
}


int wave_get(FILE*wavefile,short* sampleBuffer,int readNumSample,WAVE_INFO wave_info)////noSamples = wave_get(sndfile, sampleBuffer, readNumSample);
/* expects an interleaved 16bit pcm stream from read_samples, which it */
/* de-interleaves into buffer                                          */
{
    int          samples_read;
	samples_read = read_samples(sampleBuffer,readNumSample,wavefile,wave_info);
/*    switch(config.mpeg.mode)
    {
        case MODE_MONO  :
        case MODE_STEREO : 
        case MODE_JSTEREO:
        case MODE_DUAL   :
        default          :
            ERROR("[wav_get], channel mode not supported");
    }*/
    return samples_read;
}