diff --git a/trunk/src/app/srs_app_config.cpp b/trunk/src/app/srs_app_config.cpp
index c0673fd2f..a67ac6a9e 100644
--- a/trunk/src/app/srs_app_config.cpp
+++ b/trunk/src/app/srs_app_config.cpp
@@ -104,6 +104,7 @@ int SrsFileBuffer::fullfill(const char* filename)
     int nread = 0;
     int filesize = 0;
     
+    // TODO: FIXME: refine the file stream.
     if ((fd = ::open(filename, O_RDONLY, 0)) < 0) {
         ret = ERROR_SYSTEM_CONFIG_INVALID;
         srs_error("open conf file error. ret=%d", ret);
diff --git a/trunk/src/app/srs_app_dvr.hpp b/trunk/src/app/srs_app_dvr.hpp
index 3c4973bb7..596b4bab8 100644
--- a/trunk/src/app/srs_app_dvr.hpp
+++ b/trunk/src/app/srs_app_dvr.hpp
@@ -36,6 +36,13 @@ class SrsRequest;
 class SrsAmf0Object;
 class SrsSharedPtrMessage;
 
+/**
+* encode data to flv file.
+*/
+class SrsFlvEncoder
+{
+};
+
 /**
 * dvr(digital video recorder) to record RTMP stream to flv file.
 * TODO: FIXME: add utest for it.
diff --git a/trunk/src/app/srs_app_hls.cpp b/trunk/src/app/srs_app_hls.cpp
index 0d9480cb7..dfe1390f5 100644
--- a/trunk/src/app/srs_app_hls.cpp
+++ b/trunk/src/app/srs_app_hls.cpp
@@ -152,6 +152,7 @@ public:
     {
         int ret = ERROR_SUCCESS;
         
+        // TODO: FIXME: maybe should use st_write.
         if (::write(fd, mpegts_header, sizeof(mpegts_header)) != sizeof(mpegts_header)) {
             ret = ERROR_HLS_WRITE_FAILED;
             srs_error("write ts file header failed. ret=%d", ret);
@@ -276,6 +277,7 @@ public:
             }
             
             // write ts packet
+            // TODO: FIXME: maybe should use st_write.
             if (::write(fd, packet, sizeof(packet)) != sizeof(packet)) {
                 ret = ERROR_HLS_WRITE_FAILED;
                 srs_error("write ts file failed. ret=%d", ret);
@@ -428,6 +430,7 @@ int SrsTSMuxer::open(string _path)
     
     int flags = O_CREAT|O_WRONLY|O_TRUNC;
     mode_t mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH;
+    // TODO: FIXME: refine the file stream.
     if ((fd = ::open(path.c_str(), flags, mode)) < 0) {
         ret = ERROR_HLS_OPEN_FAILED;
         srs_error("open ts file %s failed. ret=%d", path.c_str(), ret);
diff --git a/trunk/src/app/srs_app_http_conn.cpp b/trunk/src/app/srs_app_http_conn.cpp
index 89c44162f..4a039ec20 100644
--- a/trunk/src/app/srs_app_http_conn.cpp
+++ b/trunk/src/app/srs_app_http_conn.cpp
@@ -163,6 +163,7 @@ int SrsHttpVhost::do_process_request(SrsSocket* skt, SrsHttpMessage* req)
     
     std::string fullpath = get_request_file(req);
     
+    // TODO: FIXME: refine the file stream.
     int fd = ::open(fullpath.c_str(), O_RDONLY);
     if (fd < 0) {
         ret = ERROR_HTTP_OPEN_FILE;