tools/qt-faststart.c - third_party/ffmpeg - Git at Google

 /*
  * 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>
 #include <limits.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_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 AV_WB32(p, val)    {                    \
     ((uint8_t*)(p))[0] = ((val) >> 24) & 0xff;  \
     ((uint8_t*)(p))[1] = ((val) >> 16) & 0xff;  \
     ((uint8_t*)(p))[2] = ((val) >> 8) & 0xff;   \
     ((uint8_t*)(p))[3] = (val) & 0xff;          \
     }

 #define AV_WB64(p, val)    {                    \
     AV_WB32(p, (val) >> 32)                     \
     AV_WB32(p + 4, val)                         \
     }

 #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 TRAK_ATOM QT_ATOM('t', 'r', 'a', 'k')
 #define MDIA_ATOM QT_ATOM('m', 'd', 'i', 'a')
 #define MINF_ATOM QT_ATOM('m', 'i', 'n', 'f')
 #define STBL_ATOM QT_ATOM('s', 't', 'b', 'l')
 #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
 #define MAX_FTYP_ATOM_SIZE 1048576

 typedef struct {
     uint32_t type;
     uint32_t header_size;
     uint64_t size;
     unsigned char *data;
 } atom_t;

 typedef struct {
     uint64_t moov_atom_size;
     uint64_t stco_offset_count;
     uint64_t stco_data_size;
     int stco_overflow;
     uint32_t depth;
 } update_chunk_offsets_context_t;

 typedef struct {
     unsigned char *dest;
     uint64_t original_moov_size;
     uint64_t new_moov_size;
 } upgrade_stco_context_t;

 typedef int (*parse_atoms_callback_t)(void *context, atom_t *atom);

 static int parse_atoms(
     unsigned char *buf,
     uint64_t size,
     parse_atoms_callback_t callback,
     void *context)
 {
     unsigned char *pos = buf;
     unsigned char *end = pos + size;
     atom_t atom;
     int ret;

     while (end - pos >= ATOM_PREAMBLE_SIZE) {
         atom.size = BE_32(pos);
         atom.type = BE_32(pos + 4);
         pos += ATOM_PREAMBLE_SIZE;
         atom.header_size = ATOM_PREAMBLE_SIZE;

         switch (atom.size) {
         case 1:
             if (end - pos < 8) {
                 fprintf(stderr, "not enough room for 64 bit atom size\n");
                 return -1;
             }

             atom.size = BE_64(pos);
             pos += 8;
             atom.header_size = ATOM_PREAMBLE_SIZE + 8;
             break;

         case 0:
             atom.size = ATOM_PREAMBLE_SIZE + end - pos;
             break;
         }

         if (atom.size < atom.header_size) {
             fprintf(stderr, "atom size %"PRIu64" too small\n", atom.size);
             return -1;
         }

         atom.size -= atom.header_size;

         if (atom.size > end - pos) {
             fprintf(stderr, "atom size %"PRIu64" too big\n", atom.size);
             return -1;
         }

         atom.data = pos;
         ret = callback(context, &atom);
         if (ret < 0) {
             return ret;
         }

         pos += atom.size;
     }

     return 0;
 }

 static int update_stco_offsets(update_chunk_offsets_context_t *context, atom_t *atom)
 {
     uint32_t current_offset;
     uint32_t offset_count;
     unsigned char *pos;
     unsigned char *end;

     printf(" patching stco atom...\n");
     if (atom->size < 8) {
         fprintf(stderr, "stco atom size %"PRIu64" too small\n", atom->size);
         return -1;
     }

     offset_count = BE_32(atom->data + 4);
     if (offset_count > (atom->size - 8) / 4) {
         fprintf(stderr, "stco offset count %"PRIu32" too big\n", offset_count);
         return -1;
     }

     context->stco_offset_count += offset_count;
     context->stco_data_size += atom->size - 8;

     for (pos = atom->data + 8, end = pos + offset_count * 4;
         pos < end;
         pos += 4) {
         current_offset = BE_32(pos);
         if (current_offset > UINT_MAX - context->moov_atom_size) {
             context->stco_overflow = 1;
         }
         current_offset += context->moov_atom_size;
         AV_WB32(pos, current_offset);
     }

     return 0;
 }

 static int update_co64_offsets(update_chunk_offsets_context_t *context, atom_t *atom)
 {
     uint64_t current_offset;
     uint32_t offset_count;
     unsigned char *pos;
     unsigned char *end;

     printf(" patching co64 atom...\n");
     if (atom->size < 8) {
         fprintf(stderr, "co64 atom size %"PRIu64" too small\n", atom->size);
         return -1;
     }

     offset_count = BE_32(atom->data + 4);
     if (offset_count > (atom->size - 8) / 8) {
         fprintf(stderr, "co64 offset count %"PRIu32" too big\n", offset_count);
         return -1;
     }

     for (pos = atom->data + 8, end = pos + offset_count * 8;
         pos < end;
         pos += 8) {
         current_offset = BE_64(pos);
         current_offset += context->moov_atom_size;
         AV_WB64(pos, current_offset);
     }

     return 0;
 }

 static int update_chunk_offsets_callback(void *ctx, atom_t *atom)
 {
     update_chunk_offsets_context_t *context = ctx;
     int ret;

     switch (atom->type) {
     case STCO_ATOM:
         return update_stco_offsets(context, atom);

     case CO64_ATOM:
         return update_co64_offsets(context, atom);

     case MOOV_ATOM:
     case TRAK_ATOM:
     case MDIA_ATOM:
     case MINF_ATOM:
     case STBL_ATOM:
         context->depth++;
         if (context->depth > 10) {
             fprintf(stderr, "atoms too deeply nested\n");
             return -1;
         }

         ret = parse_atoms(
             atom->data,
             atom->size,
             update_chunk_offsets_callback,
             context);
         context->depth--;
         return ret;
     }

     return 0;
 }

 static void set_atom_size(unsigned char *header, uint32_t header_size, uint64_t size)
 {
     switch (header_size) {
     case 8:
         AV_WB32(header, size);
         break;

     case 16:
         AV_WB64(header + 8, size);
         break;
     }
 }

 static void upgrade_stco_atom(upgrade_stco_context_t *context, atom_t *atom)
 {
     unsigned char *pos;
     unsigned char *end;
     uint64_t new_offset;
     uint32_t offset_count;
     uint32_t original_offset;

     /* Note: not performing validations since they were performed on the first pass */

     offset_count = BE_32(atom->data + 4);

     /* write the header */
     memcpy(context->dest, atom->data - atom->header_size, atom->header_size + 8);
     AV_WB32(context->dest + 4, CO64_ATOM);
     set_atom_size(context->dest, atom->header_size, atom->header_size + 8 + offset_count * 8);
     context->dest += atom->header_size + 8;

     /* write the data */
     for (pos = atom->data + 8, end = pos + offset_count * 4;
         pos < end;
         pos += 4) {
         original_offset = BE_32(pos) - context->original_moov_size;
         new_offset = (uint64_t)original_offset + context->new_moov_size;
         AV_WB64(context->dest, new_offset);
         context->dest += 8;
     }
 }

 static int upgrade_stco_callback(void *ctx, atom_t *atom)
 {
     upgrade_stco_context_t *context = ctx;
     unsigned char *start_pos;
     uint64_t copy_size;

     switch (atom->type) {
     case STCO_ATOM:
         upgrade_stco_atom(context, atom);
         break;

     case MOOV_ATOM:
     case TRAK_ATOM:
     case MDIA_ATOM:
     case MINF_ATOM:
     case STBL_ATOM:
         /* write the atom header */
         memcpy(context->dest, atom->data - atom->header_size, atom->header_size);
         start_pos = context->dest;
         context->dest += atom->header_size;

         /* parse internal atoms*/
         if (parse_atoms(
             atom->data,
             atom->size,
             upgrade_stco_callback,
             context) < 0) {
             return -1;
         }

         /* update the atom size */
         set_atom_size(start_pos, atom->header_size, context->dest - start_pos);
         break;

     default:
         copy_size = atom->header_size + atom->size;
         memcpy(context->dest, atom->data - atom->header_size, copy_size);
         context->dest += copy_size;
         break;
     }

     return 0;
 }

 static int update_moov_atom(
     unsigned char **moov_atom,
     uint64_t *moov_atom_size)
 {
     update_chunk_offsets_context_t update_context = { 0 };
     upgrade_stco_context_t upgrade_context;
     unsigned char *new_moov_atom;

     update_context.moov_atom_size = *moov_atom_size;

     if (parse_atoms(
         *moov_atom,
         *moov_atom_size,
         update_chunk_offsets_callback,
         &update_context) < 0) {
         return -1;
     }

     if (!update_context.stco_overflow) {
         return 0;
     }

     printf(" upgrading stco atoms to co64...\n");
     upgrade_context.new_moov_size = *moov_atom_size +
         update_context.stco_offset_count * 8 -
         update_context.stco_data_size;

     new_moov_atom = malloc(upgrade_context.new_moov_size);
     if (new_moov_atom == NULL) {
         fprintf(stderr, "could not allocate %"PRIu64" bytes for updated moov atom\n",
             upgrade_context.new_moov_size);
         return -1;
     }

     upgrade_context.original_moov_size = *moov_atom_size;
     upgrade_context.dest = new_moov_atom;

     if (parse_atoms(
         *moov_atom,
         *moov_atom_size,
         upgrade_stco_callback,
         &upgrade_context) < 0) {
         free(new_moov_atom);
         return -1;
     }

     free(*moov_atom);
     *moov_atom = new_moov_atom;
     *moov_atom_size = upgrade_context.new_moov_size;

     if (upgrade_context.dest != *moov_atom + *moov_atom_size) {
         fprintf(stderr, "unexpected - wrong number of moov bytes written\n");
         return -1;
     }

     return 0;
 }

 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;
     int64_t start_offset = 0;
     unsigned char *copy_buffer = NULL;
     int bytes_to_copy;
     uint64_t free_size = 0;
     uint64_t moov_size = 0;

     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) {
             if (atom_size > MAX_FTYP_ATOM_SIZE) {
                 fprintf(stderr, "ftyp atom size %"PRIu64" too big\n",
                        atom_size);
                 goto error_out;
             }
             ftyp_atom_size = atom_size;
             free(ftyp_atom);
             ftyp_atom = malloc(ftyp_atom_size);
             if (!ftyp_atom) {
                 fprintf(stderr, "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)) {
             fprintf(stderr, "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)
             moov_size = atom_size;

         if (moov_size && atom_type == FREE_ATOM) {
             free_size += atom_size;
             atom_type = MOOV_ATOM;
             atom_size = moov_size;
         }
     }

     if (atom_type != MOOV_ATOM) {
         printf("last atom in file was not a moov atom\n");
         free(ftyp_atom);
         fclose(infile);
         return 0;
     }

     if (atom_size < 16) {
         fprintf(stderr, "bad moov atom size\n");
         goto error_out;
     }

     /* moov atom was, in fact, the last atom in the chunk; load the whole
      * moov atom */
     if (fseeko(infile, -(atom_size + free_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) {
         fprintf(stderr, "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) {
         fprintf(stderr, "this utility does not support compressed moov atoms yet\n");
         goto error_out;
     }

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

     if (update_moov_atom(&moov_atom, &moov_atom_size) < 0) {
         goto error_out;
     }

     /* 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) {
         fprintf(stderr, "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;
 }
	/*
	* 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>
	#include <limits.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_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 AV_WB32(p, val) { \
	((uint8_t*)(p))[0] = ((val) >> 24) & 0xff; \
	((uint8_t*)(p))[1] = ((val) >> 16) & 0xff; \
	((uint8_t*)(p))[2] = ((val) >> 8) & 0xff; \
	((uint8_t*)(p))[3] = (val) & 0xff; \
	}

	#define AV_WB64(p, val) { \
	AV_WB32(p, (val) >> 32) \
	AV_WB32(p + 4, val) \
	}

	#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 TRAK_ATOM QT_ATOM('t', 'r', 'a', 'k')
	#define MDIA_ATOM QT_ATOM('m', 'd', 'i', 'a')
	#define MINF_ATOM QT_ATOM('m', 'i', 'n', 'f')
	#define STBL_ATOM QT_ATOM('s', 't', 'b', 'l')
	#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
	#define MAX_FTYP_ATOM_SIZE 1048576

	typedef struct {
	uint32_t type;
	uint32_t header_size;
	uint64_t size;
	unsigned char *data;
	} atom_t;

	typedef struct {
	uint64_t moov_atom_size;
	uint64_t stco_offset_count;
	uint64_t stco_data_size;
	int stco_overflow;
	uint32_t depth;
	} update_chunk_offsets_context_t;

	typedef struct {
	unsigned char *dest;
	uint64_t original_moov_size;
	uint64_t new_moov_size;
	} upgrade_stco_context_t;

	typedef int (parse_atoms_callback_t)(void context, atom_t *atom);

	static int parse_atoms(
	unsigned char *buf,
	uint64_t size,
	parse_atoms_callback_t callback,
	void *context)
	{
	unsigned char *pos = buf;
	unsigned char *end = pos + size;
	atom_t atom;
	int ret;

	while (end - pos >= ATOM_PREAMBLE_SIZE) {
	atom.size = BE_32(pos);
	atom.type = BE_32(pos + 4);
	pos += ATOM_PREAMBLE_SIZE;
	atom.header_size = ATOM_PREAMBLE_SIZE;

	switch (atom.size) {
	case 1:
	if (end - pos < 8) {
	fprintf(stderr, "not enough room for 64 bit atom size\n");
	return -1;
	}

	atom.size = BE_64(pos);
	pos += 8;
	atom.header_size = ATOM_PREAMBLE_SIZE + 8;
	break;

	case 0:
	atom.size = ATOM_PREAMBLE_SIZE + end - pos;
	break;
	}

	if (atom.size < atom.header_size) {
	fprintf(stderr, "atom size %"PRIu64" too small\n", atom.size);
	return -1;
	}

	atom.size -= atom.header_size;

	if (atom.size > end - pos) {
	fprintf(stderr, "atom size %"PRIu64" too big\n", atom.size);
	return -1;
	}

	atom.data = pos;
	ret = callback(context, &atom);
	if (ret < 0) {
	return ret;
	}

	pos += atom.size;
	}

	return 0;
	}

	static int update_stco_offsets(update_chunk_offsets_context_t context, atom_t atom)
	{
	uint32_t current_offset;
	uint32_t offset_count;
	unsigned char *pos;
	unsigned char *end;

	printf(" patching stco atom...\n");
	if (atom->size < 8) {
	fprintf(stderr, "stco atom size %"PRIu64" too small\n", atom->size);
	return -1;
	}

	offset_count = BE_32(atom->data + 4);
	if (offset_count > (atom->size - 8) / 4) {
	fprintf(stderr, "stco offset count %"PRIu32" too big\n", offset_count);
	return -1;
	}

	context->stco_offset_count += offset_count;
	context->stco_data_size += atom->size - 8;

	for (pos = atom->data + 8, end = pos + offset_count * 4;
	pos < end;
	pos += 4) {
	current_offset = BE_32(pos);
	if (current_offset > UINT_MAX - context->moov_atom_size) {
	context->stco_overflow = 1;
	}
	current_offset += context->moov_atom_size;
	AV_WB32(pos, current_offset);
	}

	return 0;
	}

	static int update_co64_offsets(update_chunk_offsets_context_t context, atom_t atom)
	{
	uint64_t current_offset;
	uint32_t offset_count;
	unsigned char *pos;
	unsigned char *end;

	printf(" patching co64 atom...\n");
	if (atom->size < 8) {
	fprintf(stderr, "co64 atom size %"PRIu64" too small\n", atom->size);
	return -1;
	}

	offset_count = BE_32(atom->data + 4);
	if (offset_count > (atom->size - 8) / 8) {
	fprintf(stderr, "co64 offset count %"PRIu32" too big\n", offset_count);
	return -1;
	}

	for (pos = atom->data + 8, end = pos + offset_count * 8;
	pos < end;
	pos += 8) {
	current_offset = BE_64(pos);
	current_offset += context->moov_atom_size;
	AV_WB64(pos, current_offset);
	}

	return 0;
	}

	static int update_chunk_offsets_callback(void ctx, atom_t atom)
	{
	update_chunk_offsets_context_t *context = ctx;
	int ret;

	switch (atom->type) {
	case STCO_ATOM:
	return update_stco_offsets(context, atom);

	case CO64_ATOM:
	return update_co64_offsets(context, atom);

	case MOOV_ATOM:
	case TRAK_ATOM:
	case MDIA_ATOM:
	case MINF_ATOM:
	case STBL_ATOM:
	context->depth++;
	if (context->depth > 10) {
	fprintf(stderr, "atoms too deeply nested\n");
	return -1;
	}

	ret = parse_atoms(
	atom->data,
	atom->size,
	update_chunk_offsets_callback,
	context);
	context->depth--;
	return ret;
	}

	return 0;
	}

	static void set_atom_size(unsigned char *header, uint32_t header_size, uint64_t size)
	{
	switch (header_size) {
	case 8:
	AV_WB32(header, size);
	break;

	case 16:
	AV_WB64(header + 8, size);
	break;
	}
	}

	static void upgrade_stco_atom(upgrade_stco_context_t context, atom_t atom)
	{
	unsigned char *pos;
	unsigned char *end;
	uint64_t new_offset;
	uint32_t offset_count;
	uint32_t original_offset;

	/* Note: not performing validations since they were performed on the first pass */

	offset_count = BE_32(atom->data + 4);

	/* write the header */
	memcpy(context->dest, atom->data - atom->header_size, atom->header_size + 8);
	AV_WB32(context->dest + 4, CO64_ATOM);
	set_atom_size(context->dest, atom->header_size, atom->header_size + 8 + offset_count * 8);
	context->dest += atom->header_size + 8;

	/* write the data */
	for (pos = atom->data + 8, end = pos + offset_count * 4;
	pos < end;
	pos += 4) {
	original_offset = BE_32(pos) - context->original_moov_size;
	new_offset = (uint64_t)original_offset + context->new_moov_size;
	AV_WB64(context->dest, new_offset);
	context->dest += 8;
	}
	}

	static int upgrade_stco_callback(void ctx, atom_t atom)
	{
	upgrade_stco_context_t *context = ctx;
	unsigned char *start_pos;
	uint64_t copy_size;

	switch (atom->type) {
	case STCO_ATOM:
	upgrade_stco_atom(context, atom);
	break;

	case MOOV_ATOM:
	case TRAK_ATOM:
	case MDIA_ATOM:
	case MINF_ATOM:
	case STBL_ATOM:
	/* write the atom header */
	memcpy(context->dest, atom->data - atom->header_size, atom->header_size);
	start_pos = context->dest;
	context->dest += atom->header_size;

	/* parse internal atoms*/
	if (parse_atoms(
	atom->data,
	atom->size,
	upgrade_stco_callback,
	context) < 0) {
	return -1;
	}

	/* update the atom size */
	set_atom_size(start_pos, atom->header_size, context->dest - start_pos);
	break;

	default:
	copy_size = atom->header_size + atom->size;
	memcpy(context->dest, atom->data - atom->header_size, copy_size);
	context->dest += copy_size;
	break;
	}

	return 0;
	}

	static int update_moov_atom(
	unsigned char **moov_atom,
	uint64_t *moov_atom_size)
	{
	update_chunk_offsets_context_t update_context = { 0 };
	upgrade_stco_context_t upgrade_context;
	unsigned char *new_moov_atom;

	update_context.moov_atom_size = *moov_atom_size;

	if (parse_atoms(
	*moov_atom,
	*moov_atom_size,
	update_chunk_offsets_callback,
	&update_context) < 0) {
	return -1;
	}

	if (!update_context.stco_overflow) {
	return 0;
	}

	printf(" upgrading stco atoms to co64...\n");
	upgrade_context.new_moov_size = *moov_atom_size +
	update_context.stco_offset_count * 8 -
	update_context.stco_data_size;

	new_moov_atom = malloc(upgrade_context.new_moov_size);
	if (new_moov_atom == NULL) {
	fprintf(stderr, "could not allocate %"PRIu64" bytes for updated moov atom\n",
	upgrade_context.new_moov_size);
	return -1;
	}

	upgrade_context.original_moov_size = *moov_atom_size;
	upgrade_context.dest = new_moov_atom;

	if (parse_atoms(
	*moov_atom,
	*moov_atom_size,
	upgrade_stco_callback,
	&upgrade_context) < 0) {
	free(new_moov_atom);
	return -1;
	}

	free(*moov_atom);
	*moov_atom = new_moov_atom;
	*moov_atom_size = upgrade_context.new_moov_size;

	if (upgrade_context.dest != moov_atom + moov_atom_size) {
	fprintf(stderr, "unexpected - wrong number of moov bytes written\n");
	return -1;
	}

	return 0;
	}

	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;
	int64_t start_offset = 0;
	unsigned char *copy_buffer = NULL;
	int bytes_to_copy;
	uint64_t free_size = 0;
	uint64_t moov_size = 0;

	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) {
	if (atom_size > MAX_FTYP_ATOM_SIZE) {
	fprintf(stderr, "ftyp atom size %"PRIu64" too big\n",
	atom_size);
	goto error_out;
	}
	ftyp_atom_size = atom_size;
	free(ftyp_atom);
	ftyp_atom = malloc(ftyp_atom_size);
	if (!ftyp_atom) {
	fprintf(stderr, "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)) {
	fprintf(stderr, "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)
	moov_size = atom_size;

	if (moov_size && atom_type == FREE_ATOM) {
	free_size += atom_size;
	atom_type = MOOV_ATOM;
	atom_size = moov_size;
	}
	}

	if (atom_type != MOOV_ATOM) {
	printf("last atom in file was not a moov atom\n");
	free(ftyp_atom);
	fclose(infile);
	return 0;
	}

	if (atom_size < 16) {
	fprintf(stderr, "bad moov atom size\n");
	goto error_out;
	}

	/* moov atom was, in fact, the last atom in the chunk; load the whole
	* moov atom */
	if (fseeko(infile, -(atom_size + free_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) {
	fprintf(stderr, "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) {
	fprintf(stderr, "this utility does not support compressed moov atoms yet\n");
	goto error_out;
	}

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

	if (update_moov_atom(&moov_atom, &moov_atom_size) < 0) {
	goto error_out;
	}

	/* 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) {
	fprintf(stderr, "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;
	}