/*
* read and verify the header of the recently opened file
*/
static int _mvefile_read_header(const MVEFILE *movie)
{
unsigned char buffer[26];
/* check the file is open */
if (! movie->stream)
return 0;
/* check the file is long enough */
if (! mve_read(movie->stream, buffer, 26))
return 0;
/* check the signature */
if (memcmp(buffer, MVE_HEADER, 20))
return 0;
/* check the hard-coded constants */
if (_mve_get_short(buffer+20) != MVE_HDRCONST1)
return 0;
if (_mve_get_short(buffer+22) != MVE_HDRCONST2)
return 0;
if (_mve_get_short(buffer+24) != MVE_HDRCONST3)
return 0;
return 1;
}
static int _mvefile_fetch_next_chunk(MVEFILE *movie)
{
unsigned char buffer[4];
unsigned short length;
/* fail if not open */
if (! movie->stream)
return 0;
/* fail if we can't read the next segment descriptor */
if (! mve_read(movie->stream, buffer, 4))
return 0;
/* pull out the next length */
length = _mve_get_short(buffer);
/* make sure we've got sufficient space */
_mvefile_set_buffer_size(movie, length);
/* read the chunk */
if (! mve_read(movie->stream, &movie->cur_chunk[0], length))
return 0;
movie->cur_chunk.resize(length);
movie->next_segment = 0;
return 1;
}
/*
* get the size of the next segment
*/
int_fast32_t mvefile_get_next_segment_size(const MVEFILE *movie)
{
if (!have_segment_header(movie))
return -1;
/* otherwise, get the data length */
return _mve_get_short(&movie->cur_chunk[movie->next_segment]);
}
int mvefile_get_next_segment_size (MVEFILE *movie)
{
// if nothing is cached, fail
if (movie->cur_chunk == NULL || movie->next_segment >= movie->cur_fill)
return -1;
// if we don't have enough data to get a tSegment, fail
if (movie->cur_fill - movie->next_segment < 4)
return -1;
// otherwise, get the data length
return _mve_get_short (movie->cur_chunk + movie->next_segment);
}
static int _mvefile_fetch_next_chunk (MVEFILE *movie)
{
unsigned char buffer[4];
unsigned short length;
// fail if not open
if (!movie->stream)
return 0;
// fail if we can't read the next tSegment descriptor
if (!mve_read (movie->stream, buffer, 4))
return 0;
// pull out the next length
length = _mve_get_short (buffer);
// make sure we've got sufficient space
_mvefile_set_buffer_size (movie, length);
// read the chunk
if (!mve_read (movie->stream, movie->cur_chunk, length))
return 0;
movie->cur_fill = length;
movie->next_segment = 0;
return 1;
}
