cbp.c

MPEG-4编解码的实现(包括MPEG4视音频编解码)

#include "../portab.h"
#include "cbp.h"

cbpFuncPtr calc_cbp;

/*
 * Returns a field of bits that indicates non zero ac blocks
 * for this macro block
 */
uint32_t calc_cbp_c(const int16_t codes[6*64])
{
	uint32_t i, j;
	uint32_t cbp = 0;

	for (i = 0; i < 6; i++)
	{
		for (j = 1; j < 61; j+=4)
		{
			if (codes[i*64 + j    ]|codes[i*64 + j + 1]|
			    codes[i*64 + j + 2]|codes[i*64 + j + 3])
			{
				cbp |= 1 << (5 - i);
				break;
			}
		}

		if(codes[i*64 + j]|codes[i*64 + j + 1]|codes[i*64 + j + 2])
			cbp |= 1 << (5 - i);

	}

	return cbp;

}