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TheWanderer

Unity [Solved] Problem with fread( ) usage...

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Since this topic seems to have shifted focus, I thought it might be more useful to post on this forum. What I'm trying to do is load a WAV file into memory so that I can play it back using DirectSound. To do this, I read in the header information for the file and then try to read in the sound data... which is where I fail. I've gone into fread( ) itself and looked at what it is doing and it seems to read only 6 bytes and then just gives up. When it requests the next segment from the hard disk, it seems to be receiving nothing. I know for a fact that the file is not at it's end, yet fread just quits. Here is the code for the loading of the sound file. It is based on the article here on Gamedev.net:
#include<stdlib.h>
#include<stdio.h>
#include<string.h>

SNDFILE *readWav(char *file_name)
{
 FILE *fp = NULL; 

 fp = fopen(file_name,"r");
 if (!fp) //Make sure the file was found
  return NULL;

 unsigned char id[4]; //four bytes to hold identifiers ('RIFF','WAVE','fmt ','data');
 unsigned long size; //32 bit value to hold file size
 unsigned long format_length;//Length of format header; Should be 16

 fread(id, sizeof(unsigned char), 4, fp); //read in first four bytes
 if (strncmp((const char *)id, "RIFF",4))
  return NULL;
 
 fread(&size, sizeof(unsigned long), 1, fp); //read in 32bit size value
 
 fread(id, sizeof(unsigned char), 4, fp); //read in 4 byte string
 if (strncmp((const char *)id,"WAVE",4))
  return NULL;

 fread(id, sizeof(unsigned char), 4, fp); //read in 4 bytes "fmt "; 
 if(strncmp((const char *)id, "fmt ",4))
  return NULL;

 SNDFILE *tmp = (SNDFILE *) malloc(sizeof(SNDFILE));

 fread(&format_length, sizeof(unsigned long),1,fp); //Should be 16
 fread(&tmp->wfrmt.wFormatTag, sizeof(short), 1, fp);//Should always be WAVE_FORMAT_PCM
 fread(&tmp->wfrmt.nChannels, sizeof(short),1,fp); //1 mono, 2 stereo
 fread(&tmp->wfrmt.nSamplesPerSec, sizeof(unsigned long), 1, fp); //like 44100, 22050, etc...
 fread(&tmp->wfrmt.nAvgBytesPerSec, sizeof(unsigned long), 1, fp); //Average Bytes per second
 fread(&tmp->wfrmt.nBlockAlign, sizeof(short), 1, fp); //nChannels * BytesPerSample
 fread(&tmp->wfrmt.wBitsPerSample, sizeof(short), 1, fp); //8 bit or 16 bit file?
 tmp->wfrmt.cbSize = 0;

 fread(id, sizeof(unsigned char), 4, fp); //read in identifier 'data'
 if(strncmp((const char *)id, "data",4))
 {
  free(tmp);
  return NULL;
 }

 int bytes_read; // Used to check how many bytes fread read
 fread(&tmp->size, sizeof(unsigned long), 1, fp); //how many bytes of sound data do we have
 tmp->buffer = (unsigned char *) malloc (sizeof(unsigned char) * tmp->size); //set aside sound buffer space
 //for(int i=0; i<(int)tmp->size; i++)
  //tmp->buffer = (unsigned char) rand()%256;
  //tmp->buffer=fgetc(fp);

/*!!!FAILURE ON NEXT STEP!!!*/
 bytes_read = fread(tmp->buffer, sizeof(unsigned char), tmp->size, fp); //read in our whole sound data chunk
 fclose(fp);

 FILE *out; // Test file to see what the buffer read
 out = fopen("Out.txt","w+");
 fwrite(tmp->buffer,sizeof(unsigned char),tmp->size,out);
 fclose(out); 
 return tmp;

}





And here is the definition of SNDFILE:
typedef struct{
	WAVEFORMATEX wfrmt;
	unsigned long size;
	unsigned char *buffer;
	}SNDFILE;





Thanks for reading :)

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After the first 6 bytes? so half way through:

fread(&size, sizeof(unsigned long), 1, fp); //read in 32bit size value
Also, define "quit" - does your program crash or terminate? or does fread just return and you get invalid data? or something else?

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Guest Anonymous Poster
Might not fix your problem, but you should open non-text files as "binary" to avoid OS incompatibilities (which caused me a huge amount of trouble until I figured out the cause). Open as "rb" instead of "r".

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I've added a comment at the point at which it fails. It reads all of the header information just fine. The failure takes place on the last fread (i.e. when I try to read in the data segment).

Sorry about not clarifying :P

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Quote:
Original post by Anonymous Poster
Might not fix your problem, but you should open non-text files as "binary" to avoid OS incompatibilities (which caused me a huge amount of trouble until I figured out the cause). Open as "rb" instead of "r".


If I knew who you where, I'd give you a hug (and I'd rate you up)... :P

That was indeed it the problem. :D I'd never even heard about opening up in binary mode. I guess you learn something new each day...

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