Ballofsnow at 16:12, 18 July 2007

2007-07-18T16:12:35Z

B'man: New page: `/* for disabling audio commentary tracks in MP4 streams author: DJ Grenola date: 17 July 2007 license: none (public domain) target: win32 (MINGW), recommend using...`


2007-07-18T15:49:26Z
New page: <code><nowiki>/*    for disabling audio commentary tracks in MP4 streams    author: DJ Grenola   date: 17 July 2007   license: none (public domain)   target: win32 (MINGW), recommend using...
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<code><nowiki>/*



  for disabling audio commentary tracks in MP4 streams



  author: DJ Grenola

  date: 17 July 2007

  license: none (public domain)

  target: win32 (MINGW), recommend using the free IDE from bloodshed.net

  version: beta 0.1



*/



#define LARGE_FILE_SUPPORT



#ifdef LARGE_FILE_SUPPORT

  /* not necessary for mingw/win32 but will probably become so if we start

     trying to compile it on linux and friends */

  #define _FILE_OFFSET_BITS 64

#endif



#include <stdio.h>

#include <stdlib.h>

#include <string.h>



/* #define VERBOSE */



#define CHECKBYTES_LEN 8

#define CHECKBYTES     { 0x74, 0x6B, 0x68, 0x64, 0x00, 0x00, 0x00, 0x01 }

#define REPBYTES       { 0x74, 0x6B, 0x68, 0x64, 0x00, 0x00, 0x00, 0x00 }

#define NUM_TO_SKIP    2

#define BUFSIZE        1024*1024



#ifdef LARGE_FILE_SUPPORT

  #define FOPEN fopen64

  #define FSEEK fseeko64

  #define FTELL ftello64

  #define OFF_T off64_t

#else

  #define FOPEN fopen

  #define FSEEK fseek

  #define FTELL ftell

  #define OFF_T int

#endif



typedef long long int s64;



void usage(char *argv0);



unsigned char checkbytes[CHECKBYTES_LEN]=CHECKBYTES;

unsigned char repbytes[CHECKBYTES_LEN]=REPBYTES;

unsigned char buffer[BUFSIZE];



int main (int argc, char **argv) {

  FILE *f;

  unsigned int matches=0;

  unsigned int bufstart=0;

  unsigned int bytes_to_read;

  unsigned int error=0;

  s64 br;

  OFF_T pos=0,tmp64;

  char *fname=NULL;

  printf ("MP4 audio track disabler\n");

  printf ("beta 0.1, DJ Grenola\n\n");

  printf ("This software comes with no warranty.\n\n");

  if ((argc!=2 && argc!=3) || (argc==3 && strcmp(argv[1],"-x"))) {

    usage(argv[0]);

    return 0;

  }

  fname=argv[argc-1];

  if ((f=FOPEN(fname,"r+b"))==NULL) {

    printf ("[-] Failed to open file \"%s\".\n", fname);

    return 1;

  }

  printf ("[+] Using %u KiB chunks.\n", BUFSIZE/1024);

  printf ("[+] Scanning file \"%s\".\n", fname);

  while (~0) {

    int i;

    bytes_to_read=BUFSIZE-bufstart;

    br=fread(buffer+bufstart,1,bytes_to_read,f);

    pos+=br;

#ifdef VERBOSE

    printf ("[+] Read %llu bytes.\n", pos);

#endif

    for (i=0;i<br+bufstart;i++) {

      if (!memcmp(checkbytes,buffer+i,CHECKBYTES_LEN)) {

        matches++;

        printf ("[+] Match at offset 0x%0llx", pos-br+(i-bufstart));

        if (argc==2) /* dummy mode */

          printf (", no action taken.\n");

        else {

          if (matches<=NUM_TO_SKIP)

            printf (", ignored.\n");

          else {

            printf (", attempting overwrite ...\n");

            if (matches>NUM_TO_SKIP) {

              /* FIXME: this is kind of dodgy because I don't know if off64_t

                 can be relied upon to be signed ... it works now, but in the

                 future ? */

              tmp64=-br+(i-bufstart);

              if (FSEEK(f,pos+tmp64,SEEK_SET)==-1) {

                error=3;

                printf ("[-] Error seeking to offset.\n");

                goto lbl_end;

              }

              if (fwrite(repbytes,1,CHECKBYTES_LEN,f) != CHECKBYTES_LEN) {

                error=4;

                printf ("[-] Error writing replacement string.\n");

                goto lbl_end;

              }

              /* put file pointer back (if necessary) */

              if (br==bytes_to_read) {

                if (FSEEK(f,pos,SEEK_SET)==-1) {

                  error=5;

                  printf ("[-] Error seeking to original position.\n");

                  goto lbl_end;

                }

              }

              printf ("[+] Replaced successfully.\n");

            }

          }

        }

      }

    }

    bufstart=CHECKBYTES_LEN-1;

    memmove(buffer,buffer+(BUFSIZE-(CHECKBYTES_LEN-1)),CHECKBYTES_LEN-1);

    if (br!=bytes_to_read)

      break;

  }

  lbl_end:

  if (ferror(f) || error) {

    /* FIXME: actually report some sort of useful error instead */

    printf ("[-] Erk. Something went wrong.\n");

    fclose(f);

    return error?error:2;

  }

  fclose(f);

  return 0;

}



void usage(char *argv0) {

  printf ("Usage: %s [-x] <MP4 file>\n\n", argv0);

  printf ("By default, the file is scanned and no changes are made.\n");

  printf ("Use the -x switch to force changes to the file.\n");

}</nowiki></code>

Anri-chan/Source/mp4nerf.c - Revision history

Ballofsnow at 16:12, 18 July 2007

B'man: New page: /* for disabling audio commentary tracks in MP4 streams author: DJ Grenola date: 17 July 2007 license: none (public domain) target: win32 (MINGW), recommend using...

B'man: New page: `/* for disabling audio commentary tracks in MP4 streams author: DJ Grenola date: 17 July 2007 license: none (public domain) target: win32 (MINGW), recommend using...`