int quicktime_update_positions(quicktime_t *file)
{
/* Get the sample position from the file offset */
/* for routines that change the positions of all tracks, like */
/* seek_end and seek_start but not for routines that reposition one track, like */
/* set_audio_position. */
int64_t mdat_offset = quicktime_position(file) - file->mdat.atom.start;
int64_t sample, chunk, chunk_offset;
int i;
if(file->total_atracks)
{
sample = quicktime_offset_to_sample(file->atracks[0].track, mdat_offset);
chunk = quicktime_offset_to_chunk(&chunk_offset, file->atracks[0].track, mdat_offset);
for(i = 0; i < file->total_atracks; i++)
{
file->atracks[i].current_position = sample;
file->atracks[i].current_chunk = chunk;
}
}
if(file->total_vtracks)
{
sample = quicktime_offset_to_sample(file->vtracks[0].track, mdat_offset);
chunk = quicktime_offset_to_chunk(&chunk_offset, file->vtracks[0].track, mdat_offset);
for(i = 0; i < file->total_vtracks; i++)
{
file->vtracks[i].current_position = sample;
file->vtracks[i].current_chunk = chunk;
}
}
return 0;
}
long quicktime_offset_to_sample(quicktime_trak_t *trak, long offset)
{
long chunk_offset;
long chunk = quicktime_offset_to_chunk(&chunk_offset, trak, offset);
long chunk_sample = quicktime_sample_of_chunk(trak, chunk);
long sample, sample_offset;
quicktime_stsz_table_t *table = trak->mdia.minf.stbl.stsz.table;
long total_samples = trak->mdia.minf.stbl.stsz.total_entries;
if(trak->mdia.minf.stbl.stsz.sample_size)
{
sample = chunk_sample + (offset - chunk_offset) /
trak->mdia.minf.stbl.stsz.sample_size;
}
else
for(sample = chunk_sample, sample_offset = chunk_offset;
sample_offset < offset && sample < total_samples; )
{
sample_offset += table[sample].size;
if(sample_offset < offset) sample++;
}
return sample;
}
