Question

Here is the problem: I have to change header of WAVE file, to be exact I have to change ChunkSize and SubChunk2Size. The problem is that those values use 4bytes but it seemt that using fwrite i overwrite 8 bytes:

the original:

RIFFđ WAVEfmt

edited:

RIFF(}   }  fmt

code:

FILE *nova;
nova=fopen ( "nova.wav", "wb" );

fseek ( nova, 4, SEEK_SET );
fwrite ( &brojacC,4,1,nova );
fseek ( zvuk, 44, SEEK_SET );
fwrite ( &brojacCS2,4,1,nova );

In edited file WAVE is overwritten. Something went wrong because I started at 4th byte and wrote 4 bytes and WAVE starts at 8th byte.

I hope I was at least a bit clear. Can this be done in some other way?

Answer 1

Well, according to my man fopen output:

   r      Open  text  file  for  reading.  The stream is positioned at the
          beginning of the file.

   r+     Open for reading and writing.  The stream is positioned  at  the
          beginning of the file.

   w      Truncate  file  to  zero length or create text file for writing.
          The stream is positioned at the beginning of the file.

   w+     Open for reading and writing.  The file is created  if  it  does
          not  exist, otherwise it is truncated.  The stream is positioned
          at the beginning of the file.

   a      Open for appending (writing at end of file).  The file  is  cre‐
          ated  if it does not exist.  The stream is positioned at the end
          of the file.

   a+     Open for reading and appending (writing at end  of  file).   The
          file is created if it does not exist.  The initial file position
          for reading is at the beginning  of  the  file,  but  output  is
          always appended to the end of the file.

That being said, I would definitely go forfopen("nova.wav", "r+b"), as w seems to truncate the file, and you’re reading before writing, while a appends to the end of the file, and you want to rewrite part of the file.