stsc.c

这个库实现了录象功能

/*******************************************************************************
 stsc.c

 libquicktime - A library for reading and writing quicktime/avi/mp4 files.
 http://libquicktime.sourceforge.net

 Copyright (C) 2002 Heroine Virtual Ltd.
 Copyright (C) 2002-2007 Members of the libquicktime project.

 This library is free software; you can redistribute it and/or modify it under
 the terms of the GNU Lesser General Public License as published by the Free
 Software Foundation; either version 2.1 of the License, or (at your option)
 any later version.

 This library is distributed in the hope that it will be useful, but WITHOUT
 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 details.

 You should have received a copy of the GNU Lesser General Public License along
 with this library; if not, write to the Free Software Foundation, Inc., 51
 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*******************************************************************************/ 

#include "lqt_private.h"
#include <stdlib.h>

void quicktime_stsc_init(quicktime_stsc_t *stsc)
{
	stsc->version = 0;
	stsc->flags = 0;
	stsc->total_entries = 0;
	stsc->entries_allocated = 0;
}

void quicktime_stsc_init_table(quicktime_t *file, quicktime_stsc_t *stsc)
{
	if(!stsc->entries_allocated)
	{
		stsc->total_entries = 1;
		stsc->entries_allocated = 2048;
		stsc->table = (quicktime_stsc_table_t*)calloc(1, sizeof(quicktime_stsc_table_t) * stsc->entries_allocated);
	}
}

void quicktime_stsc_init_video(quicktime_t *file, quicktime_stsc_t *stsc)
{
	quicktime_stsc_table_t *table;
	quicktime_stsc_init_table(file, stsc);
	table = &(stsc->table[0]);
	table->chunk = 1;
	table->samples = 1;
	table->id = 1;
}

void quicktime_stsc_init_audio(quicktime_t *file, quicktime_stsc_t *stsc, int sample_rate)
{
	quicktime_stsc_table_t *table;
	quicktime_stsc_init_table(file, stsc);
	table = &(stsc->table[0]);
	table->chunk = 1;
	table->samples = 0;         /* set this after completion or after every audio chunk is written */
	table->id = 1;
}

void quicktime_stsc_delete(quicktime_stsc_t *stsc)
{
	if(stsc->total_entries) free(stsc->table);
	stsc->total_entries = 0;
}

void quicktime_stsc_dump(quicktime_stsc_t *stsc)
{
	int i;
	lqt_dump("     sample to chunk (stsc)\n");
	lqt_dump("      version %d\n", stsc->version);
	lqt_dump("      flags %ld\n", stsc->flags);
	lqt_dump("      total_entries %ld\n", stsc->total_entries);
	for(i = 0; i < stsc->total_entries; i++)
	{
		lqt_dump("       chunk %ld samples %lx id %ld\n", 
			stsc->table[i].chunk, stsc->table[i].samples, stsc->table[i].id);
	}
}

void quicktime_read_stsc(quicktime_t *file, quicktime_stsc_t *stsc)
{
	int i;
	stsc->version = quicktime_read_char(file);
	stsc->flags = quicktime_read_int24(file);
	stsc->total_entries = quicktime_read_int32(file);
	
	stsc->entries_allocated = stsc->total_entries;
	stsc->table = (quicktime_stsc_table_t*)malloc(sizeof(quicktime_stsc_table_t) * stsc->total_entries);
	for(i = 0; i < stsc->total_entries; i++)
	{
		stsc->table[i].chunk = quicktime_read_int32(file);
		stsc->table[i].samples = quicktime_read_int32(file);
		stsc->table[i].id = quicktime_read_int32(file);
	}
}

void quicktime_compress_stsc(quicktime_stsc_t *stsc)
  {
  int i, last_same;

  /* This can happen, if a stream was created, but no
     samples have been written. The resulting file will be
     invalid anyway, just don't let us crash */
  
  if(!stsc->table) 
    return;

  for(i = 1, last_same = 0; i < stsc->total_entries; i++)
    {
    if(stsc->table[i].samples != stsc->table[last_same].samples)
      {
      /* An entry has a different sample count. */
      last_same++;
      if(last_same < i)
        {
        /* Move it up the list. */
        stsc->table[last_same] = stsc->table[i];
        }
      }
    }
  last_same++;
  stsc->total_entries = last_same;
  }

void quicktime_write_stsc(quicktime_t *file, quicktime_stsc_t *stsc)
  {
  int i;
  quicktime_atom_t atom;
  
  quicktime_atom_write_header(file, &atom, "stsc");

  quicktime_write_char(file, stsc->version);
  quicktime_write_int24(file, stsc->flags);
  quicktime_write_int32(file, stsc->total_entries);
  for(i = 0; i < stsc->total_entries; i++)
    {
    quicktime_write_int32(file, stsc->table[i].chunk);
    quicktime_write_int32(file, stsc->table[i].samples);
    quicktime_write_int32(file, stsc->table[i].id);
    }

  quicktime_atom_write_footer(file, &atom);
  }

int quicktime_update_stsc(quicktime_stsc_t *stsc, long chunk, long samples)
{

	if(chunk > stsc->entries_allocated)
	{
		stsc->entries_allocated = chunk * 2;
		stsc->table =(quicktime_stsc_table_t*)realloc(stsc->table, sizeof(quicktime_stsc_table_t) * stsc->entries_allocated);
	}

	stsc->table[chunk - 1].samples = samples;
	stsc->table[chunk - 1].chunk = chunk;
	stsc->table[chunk - 1].id = 1;
	if(chunk > stsc->total_entries) stsc->total_entries = chunk;
	return 0;
}

/* Optimizing while writing doesn't allow seeks during recording so */
/* entries are created for every chunk and only optimized during */
/* writeout.  Unfortunately there's no way to keep audio synchronized */
/* after overwriting  a recording as the fractional audio chunk in the */
/* middle always overwrites the previous location of a larger chunk.  On */
/* writing, the table must be optimized.  RealProducer requires an  */
/* optimized table. */