diff --git a/trunk/src/app/srs_app_config.cpp b/trunk/src/app/srs_app_config.cpp
index 9e29c6633..0850500d7 100644
--- a/trunk/src/app/srs_app_config.cpp
+++ b/trunk/src/app/srs_app_config.cpp
@@ -1835,7 +1835,7 @@ int SrsConfig::get_bw_check_limit_kbps(string vhost)
     return ::atoi(conf->arg0().c_str());
 }
 
-bool SrsConfig::get_vhost_is_edge(std::string vhost)
+bool SrsConfig::get_vhost_is_edge(string vhost)
 {
     SrsConfDirective* conf = get_vhost(vhost);
     return get_vhost_is_edge(conf);
@@ -1868,7 +1868,7 @@ SrsConfDirective* SrsConfig::get_vhost_edge_origin(string vhost)
     return conf->get("origin");
 }
 
-bool SrsConfig::get_vhost_edge_token_traverse(std::string vhost)
+bool SrsConfig::get_vhost_edge_token_traverse(string vhost)
 {
     SrsConfDirective* conf = get_vhost(vhost);
     
@@ -1965,6 +1965,32 @@ bool SrsConfig::get_engine_enabled(SrsConfDirective* engine)
     return true;
 }
 
+vector<string> SrsConfig::get_engine_vfilter(SrsConfDirective* engine)
+{
+    vector<string> vfilter;
+    
+    if (!engine) {
+        return vfilter;
+    }
+    
+    SrsConfDirective* conf = engine->get("vfilter");
+    if (!conf) {
+        return vfilter;
+    }
+    
+    for (int i = 0; i < (int)conf->directives.size(); i++) {
+        SrsConfDirective* p = conf->directives[i];
+        if (!p) {
+            continue;
+        }
+        
+        vfilter.push_back("-" + p->name);
+        vfilter.push_back(p->arg0());
+    }
+    
+    return vfilter;
+}
+
 string SrsConfig::get_engine_vcodec(SrsConfDirective* engine)
 {
     if (!engine) {
@@ -2077,15 +2103,17 @@ string SrsConfig::get_engine_vpreset(SrsConfDirective* engine)
     return conf->arg0();
 }
 
-void SrsConfig::get_engine_vparams(SrsConfDirective* engine, vector<string>& vparams)
+vector<string> SrsConfig::get_engine_vparams(SrsConfDirective* engine)
 {
+    vector<string> vparams;
+
     if (!engine) {
-        return;
+        return vparams;
     }
     
     SrsConfDirective* conf = engine->get("vparams");
     if (!conf) {
-        return;
+        return vparams;
     }
     
     for (int i = 0; i < (int)conf->directives.size(); i++) {
@@ -2097,28 +2125,8 @@ void SrsConfig::get_engine_vparams(SrsConfDirective* engine, vector<string>& vpa
         vparams.push_back("-" + p->name);
         vparams.push_back(p->arg0());
     }
-}
-
-void SrsConfig::get_engine_vfilter(SrsConfDirective* engine, vector<string>& vfilter)
-{
-    if (!engine) {
-        return;
-    }
     
-    SrsConfDirective* conf = engine->get("vfilter");
-    if (!conf) {
-        return;
-    }
-    
-    for (int i = 0; i < (int)conf->directives.size(); i++) {
-        SrsConfDirective* p = conf->directives[i];
-        if (!p) {
-            continue;
-        }
-        
-        vfilter.push_back("-" + p->name);
-        vfilter.push_back(p->arg0());
-    }
+    return vparams;
 }
 
 string SrsConfig::get_engine_acodec(SrsConfDirective* engine)
@@ -2177,15 +2185,17 @@ int SrsConfig::get_engine_achannels(SrsConfDirective* engine)
     return ::atoi(conf->arg0().c_str());
 }
 
-void SrsConfig::get_engine_aparams(SrsConfDirective* engine, vector<string>& aparams)
+vector<string> SrsConfig::get_engine_aparams(SrsConfDirective* engine)
 {
+    vector<string> aparams;
+    
     if (!engine) {
-        return;
+        return aparams;
     }
     
     SrsConfDirective* conf = engine->get("aparams");
     if (!conf) {
-        return;
+        return aparams;
     }
     
     for (int i = 0; i < (int)conf->directives.size(); i++) {
@@ -2197,6 +2207,8 @@ void SrsConfig::get_engine_aparams(SrsConfDirective* engine, vector<string>& apa
         aparams.push_back("-" + p->name);
         aparams.push_back(p->arg0());
     }
+    
+    return aparams;
 }
 
 string SrsConfig::get_engine_output(SrsConfDirective* engine)
@@ -2213,11 +2225,13 @@ string SrsConfig::get_engine_output(SrsConfDirective* engine)
     return conf->arg0();
 }
 
-void SrsConfig::get_ingesters(std::string vhost, std::vector<SrsConfDirective*>& ingeters)
+vector<SrsConfDirective*> SrsConfig::get_ingesters(string vhost)
 {
+    vector<SrsConfDirective*> ingeters;
+    
     SrsConfDirective* vhost_conf = get_vhost(vhost);
     if (!vhost_conf) {
-        return;
+        return ingeters;
     }
     
     for (int i = 0; i < (int)vhost_conf->directives.size(); i++) {
@@ -2228,10 +2242,10 @@ void SrsConfig::get_ingesters(std::string vhost, std::vector<SrsConfDirective*>&
         }
     }
     
-    return;
+    return ingeters;
 }
 
-SrsConfDirective* SrsConfig::get_ingest_by_id(std::string vhost, std::string ingest_id)
+SrsConfDirective* SrsConfig::get_ingest_by_id(string vhost, string ingest_id)
 {
     SrsConfDirective* conf = get_vhost(vhost);
     if (!conf) {
diff --git a/trunk/src/app/srs_app_config.hpp b/trunk/src/app/srs_app_config.hpp
index 42821ef7a..ec6ffd63b 100644
--- a/trunk/src/app/srs_app_config.hpp
+++ b/trunk/src/app/srs_app_config.hpp
@@ -601,97 +601,112 @@ public:
     */
     virtual std::vector<SrsConfDirective*>      get_transcode_engines(SrsConfDirective* transcode);
     /**
-    * 
+    * whether the engine is enabled.
     */
     virtual bool                get_engine_enabled(SrsConfDirective* engine);
     /**
-    * 
+    * get the vfilter of engine,
+    * the video filter set before the vcodec of FFMPEG.
+    */
+    virtual std::vector<std::string> get_engine_vfilter(SrsConfDirective* engine);
+    /**
+    * get the vcodec of engine,
+    * the codec of video, copy or libx264
     */
     virtual std::string         get_engine_vcodec(SrsConfDirective* engine);
     /**
-    * 
+    * get the vbitrate of engine,
+    * the bitrate in kbps of video, for example, 800kbps
     */
     virtual int                 get_engine_vbitrate(SrsConfDirective* engine);
     /**
-    * 
+    * get the vfps of engine.
+    * the video fps, for example, 25fps
     */
     virtual double              get_engine_vfps(SrsConfDirective* engine);
     /**
-    * 
+    * get the vwidth of engine,
+    * the video width, for example, 1024
     */
     virtual int                 get_engine_vwidth(SrsConfDirective* engine);
     /**
-    * 
+    * get the vheight of engine,
+    * the video height, for example, 576
     */
     virtual int                 get_engine_vheight(SrsConfDirective* engine);
     /**
-    * 
+    * get the vthreads of engine,
+    * the video transcode libx264 threads, for instance, 8
     */
     virtual int                 get_engine_vthreads(SrsConfDirective* engine);
     /**
-    * 
+    * get the vprofile of engine,
+    * the libx264 profile, can be high,main,baseline
     */
     virtual std::string         get_engine_vprofile(SrsConfDirective* engine);
     /**
-    * 
+    * get the vpreset of engine,
+    * the libx264 preset, can be ultrafast,superfast,veryfast,faster,fast,medium,slow,slower,veryslow,placebo
     */
     virtual std::string         get_engine_vpreset(SrsConfDirective* engine);
     /**
-    * 
+    * get the additional video params.
     */
-    virtual void                get_engine_vparams(SrsConfDirective* engine, std::vector<std::string>& vparams);
+    virtual std::vector<std::string> get_engine_vparams(SrsConfDirective* engine);
     /**
-    * 
-    */
-    virtual void                get_engine_vfilter(SrsConfDirective* engine, std::vector<std::string>& vfilter);
-    /**
-    * 
+    * get the acodec of engine,
+    * the audio codec can be copy or libaacplus
     */
     virtual std::string         get_engine_acodec(SrsConfDirective* engine);
     /**
-    * 
+    * get the abitrate of engine,
+    * the audio bitrate in kbps, for instance, 64kbps.
     */
     virtual int                 get_engine_abitrate(SrsConfDirective* engine);
     /**
-    * 
+    * get the asample_rate of engine,
+    * the audio sample_rate, for instance, 44100HZ
     */
     virtual int                 get_engine_asample_rate(SrsConfDirective* engine);
     /**
-    * 
+    * get the achannels of engine,
+    * the audio channel, for instance, 1 for mono, 2 for stereo.
     */
     virtual int                 get_engine_achannels(SrsConfDirective* engine);
     /**
-    * 
+    * get the aparams of engine,
+    * the audio additional params.
     */
-    virtual void                get_engine_aparams(SrsConfDirective* engine, std::vector<std::string>& aparams);
+    virtual std::vector<std::string> get_engine_aparams(SrsConfDirective* engine);
     /**
-    * 
+    * get the output of engine, for example, rtmp://127.0.0.1/live/livestream,
+    * @remark, we will use some variable, for instance, [vhost] to substitude with vhost.
     */
     virtual std::string         get_engine_output(SrsConfDirective* engine);
 // ingest section
 public:
     /**
-    * 
+    * get the ingest directives of vhost.
     */
-    virtual void                get_ingesters(std::string vhost, std::vector<SrsConfDirective*>& ingeters);
+    virtual std::vector<SrsConfDirective*> get_ingesters(std::string vhost);
     /**
-    * 
+    * get specified ingest.
     */
     virtual SrsConfDirective*   get_ingest_by_id(std::string vhost, std::string ingest_id);
     /**
-    * 
+    * whether ingest is enalbed.
     */
     virtual bool                get_ingest_enabled(SrsConfDirective* ingest);
     /**
-    * 
+    * get the ingest ffmpeg tool
     */
     virtual std::string         get_ingest_ffmpeg(SrsConfDirective* ingest);
     /**
-    * 
+    * get the ingest input type, file or stream.
     */
     virtual std::string         get_ingest_input_type(SrsConfDirective* ingest);
     /**
-    * 
+    * get the ingest input url.
     */
     virtual std::string         get_ingest_input_url(SrsConfDirective* ingest);
 // log section
diff --git a/trunk/src/app/srs_app_ffmpeg.cpp b/trunk/src/app/srs_app_ffmpeg.cpp
index 6e29f9d57..2db94a56a 100644
--- a/trunk/src/app/srs_app_ffmpeg.cpp
+++ b/trunk/src/app/srs_app_ffmpeg.cpp
@@ -96,21 +96,21 @@ int SrsFFMPEG::initialize_transcode(SrsConfDirective* engine)
 {
     int ret = ERROR_SUCCESS;
     
-    _srs_config->get_engine_vfilter(engine, vfilter);
-    vcodec             = _srs_config->get_engine_vcodec(engine);
-    vbitrate         = _srs_config->get_engine_vbitrate(engine);
-    vfps             = _srs_config->get_engine_vfps(engine);
-    vwidth             = _srs_config->get_engine_vwidth(engine);
-    vheight         = _srs_config->get_engine_vheight(engine);
-    vthreads         = _srs_config->get_engine_vthreads(engine);
-    vprofile         = _srs_config->get_engine_vprofile(engine);
-    vpreset         = _srs_config->get_engine_vpreset(engine);
-    _srs_config->get_engine_vparams(engine, vparams);
-    acodec             = _srs_config->get_engine_acodec(engine);
-    abitrate         = _srs_config->get_engine_abitrate(engine);
-    asample_rate     = _srs_config->get_engine_asample_rate(engine);
-    achannels         = _srs_config->get_engine_achannels(engine);
-    _srs_config->get_engine_aparams(engine, aparams);
+    vfilter             = _srs_config->get_engine_vfilter(engine);
+    vcodec              = _srs_config->get_engine_vcodec(engine);
+    vbitrate            = _srs_config->get_engine_vbitrate(engine);
+    vfps                = _srs_config->get_engine_vfps(engine);
+    vwidth              = _srs_config->get_engine_vwidth(engine);
+    vheight             = _srs_config->get_engine_vheight(engine);
+    vthreads            = _srs_config->get_engine_vthreads(engine);
+    vprofile            = _srs_config->get_engine_vprofile(engine);
+    vpreset             = _srs_config->get_engine_vpreset(engine);
+    vparams             = _srs_config->get_engine_vparams(engine);
+    acodec              = _srs_config->get_engine_acodec(engine);
+    abitrate            = _srs_config->get_engine_abitrate(engine);
+    asample_rate        = _srs_config->get_engine_asample_rate(engine);
+    achannels           = _srs_config->get_engine_achannels(engine);
+    aparams             = _srs_config->get_engine_aparams(engine);
     
     // ensure the size is even.
     vwidth -= vwidth % 2;
diff --git a/trunk/src/app/srs_app_ingest.cpp b/trunk/src/app/srs_app_ingest.cpp
index 4b2178449..322336dbc 100644
--- a/trunk/src/app/srs_app_ingest.cpp
+++ b/trunk/src/app/srs_app_ingest.cpp
@@ -93,8 +93,7 @@ int SrsIngester::parse_ingesters(SrsConfDirective* vhost)
 {
     int ret = ERROR_SUCCESS;
     
-    std::vector<SrsConfDirective*> ingesters;
-    _srs_config->get_ingesters(vhost->arg0(), ingesters);
+    std::vector<SrsConfDirective*> ingesters = _srs_config->get_ingesters(vhost->arg0());
     
     // create engine
     for (int i = 0; i < (int)ingesters.size(); i++) {