seg2input.m

seg2格式数据读取

function [record,recordid,sampleint,numsample,shotno,stationsum,firststation] = seg2input(sg2file)
% 自编
format long e;
record(1:500,4096)=0;
recordid=0;
sampleint=0;
numsample=0;
shotno=0;
stationsum=0;
firststation=0;
fileinfo = dir(sg2file); % Fileinfo is a structured array of file information.
[ro, co] = size(fileinfo);

if ro == 0
    error(['The file ', sg2file, ' is not in the present working directory.'])
else
    lastbyte = fileinfo.bytes; % Pull the size of the file out of fileinfo.
end

dataout.textheader = zeros(40, 80); % Initialize the text header.

fclose('all'); % Close any previously opened segy files.
fid = fopen(sg2file, 'r');% Open the seg2 file for reading.

if fid == -1
    error('Unable to open file.')
end


 %读文件头
s1=fread(fid, 1, 'uchar');
s2=fread(fid, 1, 'uchar');

if ((s1~=88) & (s2~=58))
    return;
end;
tracepoint(1:1000)=0;
revnum=fread(fid, 1, 'int16'); 
pointbytecount=fread(fid, 1,  'int16');
numtrace=fread(fid, 1, 'int16');
s8=fread(fid, 1, 'uchar');
s9=fread(fid, 1, 'uchar');
s10=fread(fid, 1, 'uchar');
s11=fread(fid, 1, 'uchar'); 
s12=fread(fid, 1, 'uchar');
s13=fread(fid, 1, 'uchar');
s1431=fread(fid, 18, 'uchar');

for i=1:numtrace
  tracepoint(i)=fread(fid, 1, 'int32');
end;
  fseek(fid, 32+pointbytecount, 'bof');
  temp(1:50,:)=0;
  filestring=num2str(temp); 
l1=fread(fid, 1, 'int16');
hh=0;
while(0~=l1)
    s1=fread(fid, l1-2, 'uchar');
    s2=sprintf('%s',s1);
    hh=hh+1;
     for m=1:size(s1)
        filestring(hh,m)=s1(m);
     end;
    l1=fread(fid, 1, 'int16');
end;
for m=1:hh
    if  isstr(filestring(m,:))
       if  findstr(filestring(m,:),'STATION_NUMBERS ');
           p1=length(filestring(m,:));
           p2=length('STATION_NUMBERS ');
           stationsum=str2num(deblank(filestring(m,p2+1:p1)));
       end;
       if  findstr(filestring(m,:),'FIRST_STATION_NUMBER ');
           p1=length(filestring(m,:));
           p2=length('FIRST_STATION_NUMBER ');
           firststation=str2num(deblank(filestring(m,p2+1:p1)));
       end;
       
    end;   
  end;
%读到头
for j=1:numtrace
    fseek(fid, tracepoint(j), 'bof');
     a1=fread(fid, 1, 'uchar');
     a2=fread(fid, 1, 'uchar');
    if ((a1~=34) & (a2~=68))
       return;
    end;
     blocklen=fread(fid, 1, 'int16');
     datalen=fread(fid, 1, 'int32');
     numsample=fread(fid, 1, 'int32');
     datatype=fread(fid, 1, 'uchar');
     resv=fread(fid, 19, 'uchar');
     fseek(fid, tracepoint(j)+32, 'bof');
   temp(1:50,:)=0;
  tracestring=num2str(temp); 
l1=fread(fid, 1, 'int16');
hh=0;
while(0~=l1)
    s1=fread(fid, l1-2, 'uchar');
    s2=sprintf('%s',s1);
    hh=hh+1;
     for m=1:size(s1)
        tracestring(hh,m)=s1(m);
     end;
    l1=fread(fid, 1, 'int16');
end;
for m=1:hh
    if  isstr(tracestring(m,:))
       if  findstr(tracestring(m,:),'RAW_RECORD ');
           p1=length(tracestring(m,:));
           p2=length('RAW_RECORD ');
           recordid=str2num(deblank(tracestring(m,p2+1:p1)));
       end;
       if  findstr(tracestring(m,:),'SAMPLE_INTERVAL ');
           p1=length(tracestring(m,:));
           p2=length('SAMPLE_INTERVAL ');
           sampleint=str2num(deblank(tracestring(m,p2+1:p1)));
       end;
        if  findstr(tracestring(m,:),'SOURCE_STATION_NUMBER ');
           p1=length(tracestring(m,:));
           p2=length('SOURCE_STATION_NUMBER ');
           shotno=str2num(deblank(tracestring(m,p2+1:p1)));
       end;
       
    end;   
  end;
    fseek(fid, blocklen+tracepoint(j), 'bof');
    for k=1:numsample
      record(j,k)=fread(fid, 1, 'float32');
    end;
    %plot(1:numsample,record(1,1:numsample));
end;