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FFmpeg/tools/qt-faststart.c
erankor dc16c9dd90 qt-faststart - stco offset bug fix 
when the last offsets in the stco atom are close to 4GB, the addition of
the moov atom size can overflow, causing corruption near the end of the
mp4 file.
this patch upgrades all stco atoms to co64 when such an edge case is
detected. in order to accomplish this, the implementation was changed to
walk the atom tree, instead of searching for the strings 'stco'/'co64'.
this was required since when an stco atom is changed to co64, its size
changes, and the sizes of all containing atoms (moov, trak, etc.) have
to be updated as well.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
2018-06-13 21:55:19 +02:00

667 lines
19 KiB
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/*
* 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) {
printf("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) {
printf("atom size %"PRIu64" too small\n", atom.size);
return -1;
}
atom.size -= atom.header_size;
if (atom.size > end - pos) {
printf("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) {
printf("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) {
printf("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) {
printf("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) {
printf("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) {
printf("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) {
printf("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) {
printf("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;
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) {
printf("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) {
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;
}
if (atom_size < 16) {
printf("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, 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;
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) {
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;
}
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