H264解碼SPS獲取寬高和幀率

本篇文章講述了如何解碼sps獲取寬高和幀率資訊。

#include #include #include #include typedef  unsigned int uint;

typedef unsigned char byte;
typedef unsigned long dword;
uint ue(byte *pbuff, uint nlen, uint &nstartbit)
nzeronum++;
nstartbit++;
}nstartbit ++;
//計算結果
dword dwret = 0;
for (uint i=0; i1;
if (pbuff[nstartbit / 8] & (0x80 >> (nstartbit % 8)))
nstartbit++;
}return (1
<< nzeronum) - 1 + dwret;
}int se(byte *pbuff, uint nlen, uint &nstartbit)
dword u(uint bitcount,byte * buf,uint &nstartbit)
nstartbit++;
}return dwret;
}/**
* h264的nal起始碼防競爭機制 
* *@param buf sps資料內容
* * @無返回值
*/void de_emulation_prevention(byte* buf,unsigned int* buf_size)
}return;
}/**
* *@param buf sps資料內容
*@param nlen sps資料的長度
*@param width 影象寬度
*@param height 影象高度
* @成功則返回1 , 失敗則返回0
*/int h264_decode_sps(byte * buf,unsigned int nlen,int &width,int &height,int &fps)}}
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 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;
int frame_mbs_only_flag=u(1,buf,startbit);
if(!frame_mbs_only_flag)
int mb_adaptive_frame_field_flag=u(1,buf,startbit);
int direct_8x8_inference_flag=u(1,buf,startbit);
int frame_cropping_flag=u(1,buf,startbit);
if(frame_cropping_flag)
int vui_parameter_present_flag=u(1,buf,startbit);
if(vui_parameter_present_flag)
}int overscan_info_present_flag=u(1,buf,startbit); 
if(overscan_info_present_flag)
int video_signal_type_present_flag=u(1,buf,startbit); 
if(video_signal_type_present_flag)
}int chroma_loc_info_present_flag=u(1,buf,startbit); 
if(chroma_loc_info_present_flag)
int timing_info_present_flag=u(1,buf,startbit); 
if(timing_info_present_flag)
}return
true;
}else
return
false;
}

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