trak.c

MPEG-4编解码的实现(包括MPEG4视音频编解码)

	else
	{
/* get the sample count when reading only */
		quicktime_stts_t *stts = &(trak->mdia.minf.stbl.stts);
		int i;
		long total = 0;

		for(i = 0; i < stts->total_entries; i++)
		{
			total += stts->table[i].sample_count;
		}
		return total;
	}
}

long quicktime_sample_of_chunk(quicktime_trak_t *trak, long chunk)
{
	quicktime_stsc_table_t *table = trak->mdia.minf.stbl.stsc.table;
	long total_entries = trak->mdia.minf.stbl.stsc.total_entries;
	long chunk1entry, chunk2entry;
	long chunk1, chunk2, chunks, total = 0;

	for(chunk1entry = total_entries - 1, chunk2entry = total_entries; 
		chunk1entry >= 0; 
		chunk1entry--, chunk2entry--)
	{
		chunk1 = table[chunk1entry].chunk;

		if(chunk > chunk1)
		{
			if(chunk2entry < total_entries)
			{
				chunk2 = table[chunk2entry].chunk;

				if(chunk < chunk2) chunk2 = chunk;
			}
			else
				chunk2 = chunk;

			chunks = chunk2 - chunk1;

			total += chunks * table[chunk1entry].samples;
		}
	}

	return total;
}

int quicktime_chunk_of_sample(long *chunk_sample, long *chunk, quicktime_trak_t *trak, long sample)
{
	quicktime_stsc_table_t *table = NULL;
	long total_entries = 0;
	long chunk2entry;
	long chunk1, chunk2, chunk1samples, range_samples, total = 0;

	if (trak == NULL) {
		return -1;
	}
 	table = trak->mdia.minf.stbl.stsc.table;
	total_entries = trak->mdia.minf.stbl.stsc.total_entries;

	chunk1 = 1;
	chunk1samples = 0;
	chunk2entry = 0;

	do
	{
		chunk2 = table[chunk2entry].chunk;
		*chunk = chunk2 - chunk1;
		range_samples = *chunk * chunk1samples;

		if(sample < total + range_samples) break;

		chunk1samples = table[chunk2entry].samples;
		chunk1 = chunk2;

		if(chunk2entry < total_entries)
		{
			chunk2entry++;
			total += range_samples;
		}
	}while(chunk2entry < total_entries);

	if(chunk1samples)
		*chunk = (sample - total) / chunk1samples + chunk1;
	else
		*chunk = 1;

	*chunk_sample = total + (*chunk - chunk1) * chunk1samples;
	return 0;
}

long quicktime_chunk_to_offset(quicktime_trak_t *trak, long chunk)
{
	quicktime_stco_table_t *table = NULL;

	if (trak == NULL) {
		return -1;
	}
	table = trak->mdia.minf.stbl.stco.table;

	if(trak->mdia.minf.stbl.stco.total_entries && chunk > trak->mdia.minf.stbl.stco.total_entries)
		return table[trak->mdia.minf.stbl.stco.total_entries - 1].offset;
	else
	if(trak->mdia.minf.stbl.stco.total_entries)
		return table[chunk - 1].offset;
	else
		return HEADER_LENGTH;
	
	return 0;
}

long quicktime_offset_to_chunk(long *chunk_offset, quicktime_trak_t *trak, long offset)
{
	quicktime_stco_table_t *table = trak->mdia.minf.stbl.stco.table;
	int i;

	for(i = trak->mdia.minf.stbl.stco.total_entries - 1; i >= 0; i--)
	{
		if(table[i].offset <= offset)
		{
			*chunk_offset = table[i].offset;
			return i + 1;
		}
	}
	*chunk_offset = HEADER_LENGTH;
	return 1;
}

long quicktime_sample_range_size(quicktime_trak_t *trak, long chunk_sample, long sample)
{
	quicktime_stsz_table_t *table = trak->mdia.minf.stbl.stsz.table;
	long i, total;

	if(trak->mdia.minf.stbl.stsz.sample_size)
	{
/* assume audio */
		return quicktime_samples_to_bytes(trak, sample - chunk_sample);
	}
	else
	{
/* probably video */
		for(i = chunk_sample, total = 0; i < sample; i++)
		{
			total += trak->mdia.minf.stbl.stsz.table[i].size;
		}
	}
	return total;
}

long quicktime_sample_to_offset(quicktime_trak_t *trak, long sample)
{
	long chunk, chunk_sample, chunk_offset1, chunk_offset2;

	if (trak == NULL) {
		return -1;
	}

	quicktime_chunk_of_sample(&chunk_sample, &chunk, trak, sample);
	chunk_offset1 = quicktime_chunk_to_offset(trak, chunk);
	chunk_offset2 = chunk_offset1 + quicktime_sample_range_size(trak, chunk_sample, sample);
/*printf("quicktime_sample_to_offset chunk %d sample %d chunk_offset %d chunk_sample %d chunk_offset + samples %d\n", */
/*	 chunk, sample, chunk_offset1, chunk_sample, chunk_offset2); */
	return chunk_offset2;
}

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;
}

int quicktime_update_tables(quicktime_t *file, 
							quicktime_trak_t *trak, 
							long offset, 
							long chunk, 
							long sample, 
							long samples, 
							long sample_size,
							long sample_duration,
							u_char isSyncSample,
							long renderingOffset)
{
	if (offset + sample_size > file->mdat.size) {
		file->mdat.size = offset + sample_size;
	}
	quicktime_update_stco(&(trak->mdia.minf.stbl.stco), chunk, offset);
	if (sample_size) {
		quicktime_update_stsz(&(trak->mdia.minf.stbl.stsz), sample, sample_size);
	}
	quicktime_update_stsc(&(trak->mdia.minf.stbl.stsc), chunk, samples);
	if (sample_duration) {
		quicktime_update_stts(&(trak->mdia.minf.stbl.stts), sample_duration);
	}
	if (isSyncSample) {
		quicktime_update_stss(&(trak->mdia.minf.stbl.stss), sample);
	}
	quicktime_update_ctts(&(trak->mdia.minf.stbl.ctts), renderingOffset);
	return 0;
}

int quicktime_trak_duration(quicktime_trak_t *trak, long *duration, long *timescale)
{
	quicktime_stts_t *stts = &(trak->mdia.minf.stbl.stts);
	int i;
	*duration = 0;

	/* hint track duration is that of reference track */
	if (quicktime_trak_is_hint(trak)) {
#ifdef DEBUG
		if ((quicktime_trak_t*)trak->tref.hint.traks[0] == trak) {
			printf("quicktime_trak_duration: BUG, self reference loop!!!\n");
			*duration = 0;
			*timescale = 1;
			return 0;
		}
		if ((quicktime_trak_t*)trak->tref.hint.traks[0] == NULL) {
			printf("quicktime_trak_duration: BUG, NULL reference!!!\n");
			*duration = 0;
			*timescale = 1;
			return 0;
		}
#endif /* DEBUG */

		return quicktime_trak_duration(
			(quicktime_trak_t*)trak->tref.hint.traks[0], duration, timescale);
	}

	for(i = 0; i < stts->total_entries; i++) {
		*duration += stts->table[i].sample_duration * stts->table[i].sample_count;
	}

	*timescale = trak->mdia.mdhd.time_scale;
	return 0;
}

int quicktime_trak_fix_counts(quicktime_t *file, quicktime_trak_t *trak)
{
	long samples = quicktime_track_samples(file, trak);

	if (trak->mdia.minf.stbl.stts.total_entries == 1) {
		trak->mdia.minf.stbl.stts.table[0].sample_count = samples;
	}

	if(trak->mdia.minf.stbl.stsz.sample_size)
		trak->mdia.minf.stbl.stsz.total_entries = samples;

	return 0;
}

long quicktime_chunk_samples(quicktime_trak_t *trak, long chunk)
{
	long result, current_chunk;
	quicktime_stsc_t *stsc = &(trak->mdia.minf.stbl.stsc);
	long i = stsc->total_entries - 1;

	do
	{
		current_chunk = stsc->table[i].chunk;
		result = stsc->table[i].samples;
		i--;
	}while(i >= 0 && current_chunk > chunk);

	return result;
}

int quicktime_trak_shift_offsets(quicktime_trak_t *trak, long offset)
{
	quicktime_stco_t *stco = &(trak->mdia.minf.stbl.stco);
	int i;

	for(i = 0; i < stco->total_entries; i++)
	{
		stco->table[i].offset += offset;
	}
	return 0;
}