/*

  * qt-faststart.c, v0.2

  * by Mike Melanson (melanson@pcisys.net)
  * This file is placed in the public domain. Use the program however you
  * see fit.
  *
  * This utility rearranges a Quicktime file such that the moov atom
  * is in front of the data, thus facilitating network streaming.
  *

  * To compile this program, start from the base directory from which you
  * are building FFmpeg and type:
  *  make tools/qt-faststart
  * The qt-faststart program will be built in the tools/ directory. If you
  * do not build the program in this manner, correct results are not
  * guaranteed, particularly on 64-bit platforms.

  * Invoke the program with:
  *  qt-faststart <infile.mov> <outfile.mov>
  *
  * Notes: Quicktime files can come in many configurations of top-level
  * atoms. This utility stipulates that the very last atom in the file needs
  * to be a moov atom. When given such a file, this utility will rearrange
  * the top-level atoms by shifting the moov atom from the back of the file
  * to the front, and patch the chunk offsets along the way. This utility
  * presently only operates on uncompressed moov atoms.
  */
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <inttypes.h>

 #include <string.h>

 #ifdef __MINGW32__

 #undef fseeko

 #define fseeko(x, y, z) fseeko64(x, y, z)

 #undef ftello

 #define ftello(x)       ftello64(x)

 #elif defined(_WIN32)

 #undef fseeko

 #define fseeko(x, y, z) _fseeki64(x, y, z)

 #undef ftello

 #define ftello(x)       _ftelli64(x)

 #endif
 

 #define MIN(a,b) ((a) > (b) ? (b) : (a))

 #define BE_16(x) ((((uint8_t*)(x))[0] <<  8) | ((uint8_t*)(x))[1])
 

 #define BE_32(x) (((uint32_t)(((uint8_t*)(x))[0]) << 24) |  \
                              (((uint8_t*)(x))[1]  << 16) |  \
                              (((uint8_t*)(x))[2]  <<  8) |  \
                               ((uint8_t*)(x))[3])

 
 #define BE_64(x) (((uint64_t)(((uint8_t*)(x))[0]) << 56) |  \
                   ((uint64_t)(((uint8_t*)(x))[1]) << 48) |  \
                   ((uint64_t)(((uint8_t*)(x))[2]) << 40) |  \
                   ((uint64_t)(((uint8_t*)(x))[3]) << 32) |  \
                   ((uint64_t)(((uint8_t*)(x))[4]) << 24) |  \
                   ((uint64_t)(((uint8_t*)(x))[5]) << 16) |  \
                   ((uint64_t)(((uint8_t*)(x))[6]) <<  8) |  \
                   ((uint64_t)( (uint8_t*)(x))[7]))
 
 #define BE_FOURCC(ch0, ch1, ch2, ch3)           \
     ( (uint32_t)(unsigned char)(ch3)        |   \
      ((uint32_t)(unsigned char)(ch2) <<  8) |   \
      ((uint32_t)(unsigned char)(ch1) << 16) |   \
      ((uint32_t)(unsigned char)(ch0) << 24) )

 
 #define QT_ATOM BE_FOURCC
 /* top level atoms */
 #define FREE_ATOM QT_ATOM('f', 'r', 'e', 'e')
 #define JUNK_ATOM QT_ATOM('j', 'u', 'n', 'k')
 #define MDAT_ATOM QT_ATOM('m', 'd', 'a', 't')
 #define MOOV_ATOM QT_ATOM('m', 'o', 'o', 'v')
 #define PNOT_ATOM QT_ATOM('p', 'n', 'o', 't')
 #define SKIP_ATOM QT_ATOM('s', 'k', 'i', 'p')
 #define WIDE_ATOM QT_ATOM('w', 'i', 'd', 'e')
 #define PICT_ATOM QT_ATOM('P', 'I', 'C', 'T')
 #define FTYP_ATOM QT_ATOM('f', 't', 'y', 'p')

 #define UUID_ATOM QT_ATOM('u', 'u', 'i', 'd')

 
 #define CMOV_ATOM QT_ATOM('c', 'm', 'o', 'v')
 #define STCO_ATOM QT_ATOM('s', 't', 'c', 'o')
 #define CO64_ATOM QT_ATOM('c', 'o', '6', '4')
 

 #define ATOM_PREAMBLE_SIZE    8

 #define COPY_BUFFER_SIZE   33554432

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

     FILE *infile  = NULL;
     FILE *outfile = NULL;

     unsigned char atom_bytes[ATOM_PREAMBLE_SIZE];

     uint32_t atom_type   = 0;
     uint64_t atom_size   = 0;

     uint64_t atom_offset = 0;

     int64_t last_offset;

     unsigned char *moov_atom = NULL;

     unsigned char *ftyp_atom = NULL;

     uint64_t moov_atom_size;

     uint64_t ftyp_atom_size = 0;

     uint64_t i, j;
     uint32_t offset_count;
     uint64_t current_offset;

     int64_t start_offset = 0;

     unsigned char *copy_buffer = NULL;

     int bytes_to_copy;
 
     if (argc != 3) {

         printf("Usage: qt-faststart <infile.mov> <outfile.mov>\n"
                "Note: alternatively you can use -movflags +faststart in ffmpeg\n");

         return 0;
     }
 

     if (!strcmp(argv[1], argv[2])) {
         fprintf(stderr, "input and output files need to be different\n");
         return 1;
     }
 

     infile = fopen(argv[1], "rb");
     if (!infile) {
         perror(argv[1]);

         goto error_out;

     }
 
     /* traverse through the atoms in the file to make sure that 'moov' is
      * at the end */
     while (!feof(infile)) {
         if (fread(atom_bytes, ATOM_PREAMBLE_SIZE, 1, infile) != 1) {
             break;
         }

         atom_size = BE_32(&atom_bytes[0]);

         atom_type = BE_32(&atom_bytes[4]);
 

         /* keep ftyp atom */
         if (atom_type == FTYP_ATOM) {
             ftyp_atom_size = atom_size;

             free(ftyp_atom);

             ftyp_atom = malloc(ftyp_atom_size);
             if (!ftyp_atom) {

                 printf("could not allocate %"PRIu64" bytes for ftyp atom\n",
                        atom_size);

                 goto error_out;

             }

             if (fseeko(infile, -ATOM_PREAMBLE_SIZE, SEEK_CUR) ||

                 fread(ftyp_atom, atom_size, 1, infile) != 1 ||

                 (start_offset = ftello(infile)) < 0) {

                 perror(argv[1]);

                 goto error_out;

             }

         } else {

             int ret;

             /* 64-bit special case */
             if (atom_size == 1) {
                 if (fread(atom_bytes, ATOM_PREAMBLE_SIZE, 1, infile) != 1) {
                     break;
                 }
                 atom_size = BE_64(&atom_bytes[0]);

                 ret = fseeko(infile, atom_size - ATOM_PREAMBLE_SIZE * 2, SEEK_CUR);

             } else {

                 ret = fseeko(infile, atom_size - ATOM_PREAMBLE_SIZE, SEEK_CUR);
             }

             if (ret) {

                 perror(argv[1]);
                 goto error_out;

             }
         }

         printf("%c%c%c%c %10"PRIu64" %"PRIu64"\n",
                (atom_type >> 24) & 255,
                (atom_type >> 16) & 255,
                (atom_type >>  8) & 255,
                (atom_type >>  0) & 255,
                atom_offset,
                atom_size);
         if ((atom_type != FREE_ATOM) &&
             (atom_type != JUNK_ATOM) &&
             (atom_type != MDAT_ATOM) &&
             (atom_type != MOOV_ATOM) &&
             (atom_type != PNOT_ATOM) &&
             (atom_type != SKIP_ATOM) &&
             (atom_type != WIDE_ATOM) &&
             (atom_type != PICT_ATOM) &&
             (atom_type != UUID_ATOM) &&
             (atom_type != FTYP_ATOM)) {

             printf("encountered non-QT top-level atom (is this a QuickTime file?)\n");

             break;
         }
         atom_offset += atom_size;

 
         /* The atom header is 8 (or 16 bytes), if the atom size (which
          * includes these 8 or 16 bytes) is less than that, we won't be
          * able to continue scanning sensibly after this atom, so break. */
         if (atom_size < 8)
             break;

     }

 
     if (atom_type != MOOV_ATOM) {

         printf("last atom in file was not a moov atom\n");

         free(ftyp_atom);

         fclose(infile);
         return 0;
     }
 
     /* moov atom was, in fact, the last atom in the chunk; load the whole
      * moov atom */

     if (fseeko(infile, -atom_size, SEEK_END)) {
         perror(argv[1]);
         goto error_out;
     }

     last_offset    = ftello(infile);

     if (last_offset < 0) {
         perror(argv[1]);
         goto error_out;
     }

     moov_atom_size = atom_size;

     moov_atom      = malloc(moov_atom_size);

     if (!moov_atom) {

         printf("could not allocate %"PRIu64" bytes for moov atom\n", atom_size);

         goto error_out;

     }
     if (fread(moov_atom, atom_size, 1, infile) != 1) {
         perror(argv[1]);

         goto error_out;

     }
 
     /* this utility does not support compressed atoms yet, so disqualify
      * files with compressed QT atoms */
     if (BE_32(&moov_atom[12]) == CMOV_ATOM) {

         printf("this utility does not support compressed moov atoms yet\n");

         goto error_out;

     }
 
     /* close; will be re-opened later */
     fclose(infile);

     infile = NULL;

 
     /* crawl through the moov chunk in search of stco or co64 atoms */
     for (i = 4; i < moov_atom_size - 4; i++) {
         atom_type = BE_32(&moov_atom[i]);
         if (atom_type == STCO_ATOM) {

             printf(" patching stco atom...\n");

             atom_size = BE_32(&moov_atom[i - 4]);
             if (i + atom_size - 4 > moov_atom_size) {

                 printf(" bad atom size\n");

                 goto error_out;

             }
             offset_count = BE_32(&moov_atom[i + 8]);

             if (i + 12 + offset_count * UINT64_C(4) > moov_atom_size) {
                 printf(" bad atom size/element count\n");

                 goto error_out;
             }

             for (j = 0; j < offset_count; j++) {

                 current_offset  = BE_32(&moov_atom[i + 12 + j * 4]);

                 current_offset += moov_atom_size;
                 moov_atom[i + 12 + j * 4 + 0] = (current_offset >> 24) & 0xFF;
                 moov_atom[i + 12 + j * 4 + 1] = (current_offset >> 16) & 0xFF;
                 moov_atom[i + 12 + j * 4 + 2] = (current_offset >>  8) & 0xFF;
                 moov_atom[i + 12 + j * 4 + 3] = (current_offset >>  0) & 0xFF;
             }
             i += atom_size - 4;
         } else if (atom_type == CO64_ATOM) {

             printf(" patching co64 atom...\n");

             atom_size = BE_32(&moov_atom[i - 4]);
             if (i + atom_size - 4 > moov_atom_size) {

                 printf(" bad atom size\n");

                 goto error_out;

             }
             offset_count = BE_32(&moov_atom[i + 8]);

             if (i + 12 + offset_count * UINT64_C(8) > moov_atom_size) {
                 printf(" bad atom size/element count\n");

                 goto error_out;
             }

             for (j = 0; j < offset_count; j++) {

                 current_offset  = BE_64(&moov_atom[i + 12 + j * 8]);

                 current_offset += moov_atom_size;
                 moov_atom[i + 12 + j * 8 + 0] = (current_offset >> 56) & 0xFF;
                 moov_atom[i + 12 + j * 8 + 1] = (current_offset >> 48) & 0xFF;
                 moov_atom[i + 12 + j * 8 + 2] = (current_offset >> 40) & 0xFF;
                 moov_atom[i + 12 + j * 8 + 3] = (current_offset >> 32) & 0xFF;
                 moov_atom[i + 12 + j * 8 + 4] = (current_offset >> 24) & 0xFF;
                 moov_atom[i + 12 + j * 8 + 5] = (current_offset >> 16) & 0xFF;
                 moov_atom[i + 12 + j * 8 + 6] = (current_offset >>  8) & 0xFF;
                 moov_atom[i + 12 + j * 8 + 7] = (current_offset >>  0) & 0xFF;
             }
             i += atom_size - 4;
         }
     }
 
     /* re-open the input file and open the output file */
     infile = fopen(argv[1], "rb");
     if (!infile) {
         perror(argv[1]);

         goto error_out;

     }

 
     if (start_offset > 0) { /* seek after ftyp atom */

         if (fseeko(infile, start_offset, SEEK_SET)) {
             perror(argv[1]);
             goto error_out;
         }
 

         last_offset -= start_offset;
     }

     outfile = fopen(argv[2], "wb");
     if (!outfile) {
         perror(argv[2]);

         goto error_out;

     }
 

     /* dump the same ftyp atom */
     if (ftyp_atom_size > 0) {

         printf(" writing ftyp atom...\n");

         if (fwrite(ftyp_atom, ftyp_atom_size, 1, outfile) != 1) {
             perror(argv[2]);
             goto error_out;
         }
     }
 

     /* dump the new moov atom */

     printf(" writing moov atom...\n");

     if (fwrite(moov_atom, moov_atom_size, 1, outfile) != 1) {
         perror(argv[2]);
         goto error_out;
     }
 
     /* copy the remainder of the infile, from offset 0 -> last_offset - 1 */

     bytes_to_copy = MIN(COPY_BUFFER_SIZE, last_offset);

     copy_buffer = malloc(bytes_to_copy);

     if (!copy_buffer) {

         printf("could not allocate %d bytes for copy_buffer\n", bytes_to_copy);

         goto error_out;
     }

     printf(" copying rest of file...\n");

     while (last_offset) {

         bytes_to_copy = MIN(bytes_to_copy, last_offset);

 
         if (fread(copy_buffer, bytes_to_copy, 1, infile) != 1) {
             perror(argv[1]);
             goto error_out;
         }
         if (fwrite(copy_buffer, bytes_to_copy, 1, outfile) != 1) {
             perror(argv[2]);
             goto error_out;
         }
         last_offset -= bytes_to_copy;
     }
 
     fclose(infile);
     fclose(outfile);
     free(moov_atom);

     free(ftyp_atom);

     free(copy_buffer);

 
     return 0;
 
 error_out:

     if (infile)

         fclose(infile);

     if (outfile)

         fclose(outfile);

     free(moov_atom);

     free(ftyp_atom);

     free(copy_buffer);

     return 1;
 }