从H264码流中获取视频宽高 (SPS帧)

获取.h264视频宽高的方法

花了2个通宵终于搞定。（后面附上完整代码）

http://write.blog.csdn.net/postedit/7852406

图像的高和宽在H264的SPS帧中。
在H264码流中，都是以"0x00 0x00 0x01"或者"0x00 0x00 0x00 0x01"为开始码的,找到开始码之后,使用开始码之后的第一个字节的低5位判断是否为7(sps)，等于7表示该帧就是SPS帧，从该帧就可以解析出高和宽，SPS是个结构体，里面有两个成员：pic_width_in_mbs_minus1，pic_height_in_map_units_minus_1，分别表示图像的宽和高，以宏块（16x16）为单位的值减1，因此，实际的宽为 (pic_width_in_mbs_minus1+1)*16，高为 (pic_height_in_map_units_minus_1+1)*16

http://write.blog.csdn.net/postedit/7852406

  1 UINT Ue(BYTE *pBuff, UINT nLen, UINT &nStartBit)
  2 {
  3     //计算0bit的个数
  4     UINT nZeroNum = 0;
  5     while (nStartBit < nLen * 8)
  6     {
  7         if (pBuff[nStartBit / 8] & (0x80 >> (nStartBit % 8))) //&:按位与，%取余
  8         {
  9             break;
 10         }
 11         nZeroNum++;
 12         nStartBit++;
 13     }
 14     nStartBit ++;
 15 
 16 
 17     //计算结果
 18     DWORD dwRet = 0;
 19     for (UINT i=0; i<nZeroNum; i++)
 20     {
 21         dwRet <<= 1;
 22         if (pBuff[nStartBit / 8] & (0x80 >> (nStartBit % 8)))
 23         {
 24             dwRet += 1;
 25         }
 26         nStartBit++;
 27     }
 28     return (1 << nZeroNum) - 1 + dwRet;
 29 }
 30 
 31 
 32 int Se(BYTE *pBuff, UINT nLen, UINT &nStartBit)
 33 {
 34 
 35 
 36 int UeVal=Ue(pBuff,nLen,nStartBit);
 37 double k=UeVal;
 38 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
 39 if (UeVal % 2==0)
 40 nValue=-nValue;
 41      return nValue;
 42 
 43 
 44 }
 45 
 46 
 47 DWORD u(UINT BitCount,BYTE * buf,UINT &nStartBit)
 48 {
 49     DWORD dwRet = 0;
 50     for (UINT i=0; i<BitCount; i++)
 51     {
 52         dwRet <<= 1;
 53         if (buf[nStartBit / 8] & (0x80 >> (nStartBit % 8)))
 54         {
 55             dwRet += 1;
 56         }
 57         nStartBit++;
 58     }
 59 return dwRet;
 60 }
 61 
 62 
 63 bool h264_decode_seq_parameter_set(BYTE * buf,UINT nLen,int &Width,int &Height)
 64 {
 65 UINT StartBit=0; 
 66 int forbidden_zero_bit=u(1,buf,StartBit);
 67 int nal_ref_idc=u(2,buf,StartBit);
 68 int nal_unit_type=u(5,buf,StartBit);
 69 if(nal_unit_type==7)
 70 {
 71 int profile_idc=u(8,buf,StartBit);
 72 int constraint_set0_flag=u(1,buf,StartBit);//(buf[1] & 0x80)>>7;
 73 int constraint_set1_flag=u(1,buf,StartBit);//(buf[1] & 0x40)>>6;
 74 int constraint_set2_flag=u(1,buf,StartBit);//(buf[1] & 0x20)>>5;
 75 int constraint_set3_flag=u(1,buf,StartBit);//(buf[1] & 0x10)>>4;
 76 int reserved_zero_4bits=u(4,buf,StartBit);
 77 int level_idc=u(8,buf,StartBit);
 78 
 79 int seq_parameter_set_id=Ue(buf,nLen,StartBit);
 80 
 81 if( profile_idc == 100 || profile_idc == 110 ||
 82 profile_idc == 122 || profile_idc == 144 )
 83 {
 84 int chroma_format_idc=Ue(buf,nLen,StartBit);
 85 if( chroma_format_idc == 3 )
 86 int residual_colour_transform_flag=u(1,buf,StartBit);
 87 int bit_depth_luma_minus8=Ue(buf,nLen,StartBit);
 88 int bit_depth_chroma_minus8=Ue(buf,nLen,StartBit);
 89 int qpprime_y_zero_transform_bypass_flag=u(1,buf,StartBit);
 90 int seq_scaling_matrix_present_flag=u(1,buf,StartBit);
 91 
 92 int seq_scaling_list_present_flag[8];
 93 if( seq_scaling_matrix_present_flag )
 94 {
 95 for( int i = 0; i < 8; i++ ) {
 96 seq_scaling_list_present_flag[i]=u(1,buf,StartBit);
 97 }
 98 }
 99 }
100 int log2_max_frame_num_minus4=Ue(buf,nLen,StartBit);
101 int pic_order_cnt_type=Ue(buf,nLen,StartBit);
102 if( pic_order_cnt_type == 0 )
103 int log2_max_pic_order_cnt_lsb_minus4=Ue(buf,nLen,StartBit);
104 else if( pic_order_cnt_type == 1 )
105 {
106 int delta_pic_order_always_zero_flag=u(1,buf,StartBit);
107 int offset_for_non_ref_pic=Se(buf,nLen,StartBit);
108 int offset_for_top_to_bottom_field=Se(buf,nLen,StartBit);
109 int num_ref_frames_in_pic_order_cnt_cycle=Ue(buf,nLen,StartBit);
110 
111 int *offset_for_ref_frame=new int[num_ref_frames_in_pic_order_cnt_cycle];
112 for( int i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; i++ )
113 offset_for_ref_frame[i]=Se(buf,nLen,StartBit);
114 delete [] offset_for_ref_frame;
115 }
116 int num_ref_frames=Ue(buf,nLen,StartBit);
117 int gaps_in_frame_num_value_allowed_flag=u(1,buf,StartBit);
118 int pic_width_in_mbs_minus1=Ue(buf,nLen,StartBit);
119 int pic_height_in_map_units_minus1=Ue(buf,nLen,StartBit);
120 
121 Width=(pic_width_in_mbs_minus1+1)*16;
122 Height=(pic_height_in_map_units_minus1+1)*16;
123 
124 return true;
125 }
126 else
127 return false;
128 }
129 
130 
131 
132 
133 void CCommDlg::OnOK() 
134 {
135 CString  str;
136 //数据必须把H264的头0x000001去掉
137 BYTE bytes[11]={0x67,0x64,0x08,0x1F,0xAC,0x34,0xC1,0x08,0x28,0x0F,0x64};
138 UINT startbit=0;
139 int Width,Height;
140 if (h264_decode_seq_parameter_set(bytes,11,Width,Height))
141 {
142 str.Format("%d-%d",Width,Height);
143 
144 
145 AfxMessageBox(str);
146 }
147 }