代码是借鉴的别人的
#include <cstdint>
#include <cmath>
uint32_t Ue(uint8_t *pBuff, uint32_t nLen, uint32_t &nStartBit)
{
//计算0bit的个数
uint32_t nZeroNum = 0;
while (nStartBit < nLen * 8)
{
if (pBuff[nStartBit / 8] & (0x80 >> (nStartBit % 8))) //&:按位与,%取余
{
break;
}
nZeroNum++;
nStartBit++;
}
nStartBit ++;
//计算结果
uint32_t dwRet = 0;
for (uint32_t i=0; i<nZeroNum; i++)
{
dwRet <<= 1;
if (pBuff[nStartBit / 8] & (0x80 >> (nStartBit % 8)))
{
dwRet += 1;
}
nStartBit++;
}
return (1 << nZeroNum) - 1 + dwRet;
}
int Se(uint8_t *pBuff, uint32_t nLen, uint32_t &nStartBit)
{
int UeVal=Ue(pBuff,nLen,nStartBit);
double k=UeVal;
int nValue=ceil(k/2);//ceil函数:ceil函数的作用是求不小于给定实数的最小整数。ceil(2)=ceil(1.2)=cei(1.5)=2.00
if (UeVal % 2==0)
nValue=-nValue;
return nValue;
}
uint32_t u(uint32_t BitCount,uint8_t * buf,uint32_t &nStartBit)
{
uint32_t dwRet = 0;
for (uint32_t i=0; i<BitCount; i++)
{
dwRet <<= 1;
if (buf[nStartBit / 8] & (0x80 >> (nStartBit % 8)))
{
dwRet += 1;
}
nStartBit++;
}
return dwRet;
}
bool h264_decode_seq_parameter_set(uint8_t * buf,uint32_t nLen,int &Width,int &Height)
{
uint32_t StartBit=0;
int forbidden_zero_bit=u(1,buf,StartBit);
int nal_ref_idc=u(2,buf,StartBit);
int nal_unit_type=u(5,buf,StartBit);
if(nal_unit_type==7)
{
int profile_idc=u(8,buf,StartBit);
int constraint_set0_flag=u(1,buf,StartBit);//(buf[1] & 0x80)>>7;
int constraint_set1_flag=u(1,buf,StartBit);//(buf[1] & 0x40)>>6;
int constraint_set2_flag=u(1,buf,StartBit);//(buf[1] & 0x20)>>5;
int constraint_set3_flag=u(1,buf,StartBit);//(buf[1] & 0x10)>>4;
int reserved_zero_4bits=u(4,buf,StartBit);
int level_idc=u(8,buf,StartBit);
int seq_parameter_set_id=Ue(buf,nLen,StartBit);
if( profile_idc == 100 || profile_idc == 110 ||
profile_idc == 122 || profile_idc == 144 )
{
int chroma_format_idc=Ue(buf,nLen,StartBit);
if( chroma_format_idc == 3 )
int residual_colour_transform_flag=u(1,buf,StartBit);
int bit_depth_luma_minus8=Ue(buf,nLen,StartBit);
int bit_depth_chroma_minus8=Ue(buf,nLen,StartBit);
int qpprime_y_zero_transform_bypass_flag=u(1,buf,StartBit);
int seq_scaling_matrix_present_flag=u(1,buf,StartBit);
int seq_scaling_list_present_flag[8];
if( seq_scaling_matrix_present_flag )
{
for( int i = 0; i < 8; i++ ) {
seq_scaling_list_present_flag[i]=u(1,buf,StartBit);
}
}
}
int log2_max_frame_num_minus4=Ue(buf,nLen,StartBit);
int pic_order_cnt_type=Ue(buf,nLen,StartBit);
if( pic_order_cnt_type == 0 )
int log2_max_pic_order_cnt_lsb_minus4=Ue(buf,nLen,StartBit);
else if( pic_order_cnt_type == 1 )
{
int delta_pic_order_always_zero_flag=u(1,buf,StartBit);
int offset_for_non_ref_pic=Se(buf,nLen,StartBit);
int offset_for_top_to_bottom_field=Se(buf,nLen,StartBit);
int num_ref_frames_in_pic_order_cnt_cycle=Ue(buf,nLen,StartBit);
int *offset_for_ref_frame=new int[num_ref_frames_in_pic_order_cnt_cycle];
for( int i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; i++ )
offset_for_ref_frame[i]=Se(buf,nLen,StartBit);
delete [] offset_for_ref_frame;
}
int num_ref_frames=Ue(buf,nLen,StartBit);
int gaps_in_frame_num_value_allowed_flag=u(1,buf,StartBit);
int pic_width_in_mbs_minus1=Ue(buf,nLen,StartBit);
int pic_height_in_map_units_minus1=Ue(buf,nLen,StartBit);
Width=(pic_width_in_mbs_minus1+1)*16;
Height=(pic_height_in_map_units_minus1+1)*16;
return true;
}
else
return false;
}
int main()
{
//数据必须把H264的头0x000001去掉
// uint8_t str[11]={0x67,0x64,0x08,0x1F,0xAC,0x34,0xC1,0x08,0x28,0x0F,0x64};
uint8_t str[25] = {0x67,0x64,0x00,0x1F,0xAC,0x2C,0xAC,0x05,0x00,0x5B,0xB0,0x11,0x00,0x00,0x03,0x03,0xE8,0x00,0x00,0xC3,0x50,0x8F,0x1C,0x31,0x38};
uint32_t startbit=0;
int Width,Height;
if (h264_decode_seq_parameter_set(str,11,Width,Height))
{
}
return 0;
}
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