myvtm/Other/libfilecryption/mp4info.cpp

#include "stdafx.h"
#include "mp4info.h"


static unsigned int big_to_small_endian_32bit(unsigned int const big)
{
	unsigned int data = big;
	unsigned int uret = 0;
	uret += (data >> 0 & 0xff) << 24;
	uret += (data >> 8 & 0xff) << 16;
	uret += (data >> 16 & 0xff) << 8;
	uret += (data >> 24 & 0xff) << 0;
	return uret;
}



//ftyp, free, mdat box not encryt
unsigned int get_noencrypt_boxs_size(FILE* pSrcFile, const filecryption_callback_t* pcallback, bool bgetmoov)
{
	unsigned int uret = 0;
	if (NULL == pSrcFile) {
		return uret;
	}

	int ipostion = ftell(pSrcFile);
	//ftyp box
	box_head_t box_head;
	fread(&box_head, sizeof(box_head_t), 1, pSrcFile);
	unsigned int uboxsize = big_to_small_endian_32bit(box_head.ibox_size);
	if (BOX_FTYP != big_to_small_endian_32bit(box_head.box_type)) {
		safe_log(pcallback, "get ftyp box failed.");
		return 0;
	}
	safe_log(pcallback, "get ftyp box success, box size is %d.", uboxsize);
	uret += uboxsize;
	fseek(pSrcFile, uboxsize - sizeof(box_head_t), SEEK_CUR);

	//free box
	fread(&box_head, sizeof(box_head_t), 1, pSrcFile);
	uboxsize = big_to_small_endian_32bit(box_head.ibox_size);
	if (FREE_BOX != big_to_small_endian_32bit(box_head.box_type)) {
		safe_log(pcallback, "get free box failed.");
		return 0;
	}
	safe_log(pcallback, "get free box success, box size is %d.", uboxsize);
	uret += uboxsize;
	fseek(pSrcFile, uboxsize - sizeof(box_head_t), SEEK_CUR);

	//mdat box 
	fread(&box_head, sizeof(box_head_t), 1, pSrcFile);
	uboxsize = big_to_small_endian_32bit(box_head.ibox_size);
	if (MDAT_BOX != big_to_small_endian_32bit(box_head.box_type)) {
		safe_log(pcallback, "get mdat box failed.");
		return 0;
	}
	safe_log(pcallback, "get mdat box success, box size is %d.", uboxsize);
	uret += uboxsize;
	safe_log(pcallback, "ftyp box, free box and mdat box total size is %u.", uret);

	//moov box
	if (bgetmoov) {
		fseek(pSrcFile, uboxsize - sizeof(box_head_t), SEEK_CUR);
		fread(&box_head, sizeof(box_head_t), 1, pSrcFile);
		uboxsize = big_to_small_endian_32bit(box_head.ibox_size);
		if (MOOV_BOX != big_to_small_endian_32bit(box_head.box_type)) {
			safe_log(pcallback, "get moov box failed.");
			return 0;
		}
		safe_log(pcallback, "get moov box success, box size is %d.", uboxsize);
	}

	fseek(pSrcFile, ipostion, SEEK_SET);

	return uret;
}