my $buf="";

#append to buffer until headers are found and removed

while (!($buf=~s/^.*?#### end_ascii_header\n//)) {
  sysread(INP,$buf,1024,length($buf)); 
}

syswrite(OUT,$buf,$length($buf));

#copy the rest of the file
while (sysread(INP,$buf,16384)) {
  syswrite(OUT,$buf,length($buf));
}