diff --git a/speechx/speechx/decoder/param.h b/speechx/speechx/decoder/param.h
index 1f13bbc0e468c97e7206006a9087a93dfa4e6600..1a332755da0ee2a3279da0c06e11ceb1d86790ca 100644
--- a/speechx/speechx/decoder/param.h
+++ b/speechx/speechx/decoder/param.h
@@ -20,6 +20,7 @@
 
 // feature
 DEFINE_bool(use_fbank, false, "False for fbank; or linear feature");
+DEFINE_bool(fill_zero, false, "fill zero at last chunk, when chunk < chunk_size");
 // DEFINE_bool(to_float32, true, "audio convert to pcm32. True for linear
 // feature, or fbank");
 DEFINE_int32(num_bins, 161, "num bins of mel");
diff --git a/speechx/speechx/frontend/audio/assembler.cc b/speechx/speechx/frontend/audio/assembler.cc
index bbd0944225f845f9c0751dab9c5ca7175469740d..26a3905bdf52bfef64c7689c16451dc647d49663 100644
--- a/speechx/speechx/frontend/audio/assembler.cc
+++ b/speechx/speechx/frontend/audio/assembler.cc
@@ -47,17 +47,16 @@ bool Assembler::Read(kaldi::Vector<kaldi::BaseFloat>* feats) {
 // read frame by frame from base_feature_extractor_ into cache_
 bool Assembler::Compute(Vector<BaseFloat>* feats) {
     // compute and feed frame by frame
-    bool result = false;
     while (feature_cache_.size() < frame_chunk_size_) {
         Vector<BaseFloat> feature;
-        result = base_extractor_->Read(&feature);
+        bool result = base_extractor_->Read(&feature);
         if (result == false || feature.Dim() == 0) {
-            VLOG(1) << "result: " << result << "feature dim: " << feature.Dim();
+            VLOG(1) << "result: " << result << " feature dim: " << feature.Dim();
             if (IsFinished() == false) {
-                LOG(INFO) << "finished reading feature. cache size: " << feature_cache_.size();
+                VLOG(1) << "finished reading feature. cache size: " << feature_cache_.size();
                 return false;
             } else {
-                LOG(INFO) << "break";
+                VLOG(1) << "break";
                 break;
             }
         }
@@ -103,7 +102,7 @@ bool Assembler::Compute(Vector<BaseFloat>* feats) {
   
         counter++;
     }
-    CHECK(feature_cache_.size() == cache_size_ );
+    CHECK(feature_cache_.size() == cache_size_);
 
     return true;
 }
diff --git a/speechx/speechx/frontend/audio/feature_pipeline.h b/speechx/speechx/frontend/audio/feature_pipeline.h
index d91a70e352ffe85689e666b37d1b6e2d8f971e81..e06995b17ac7135d8b6812888b12e4a2b07237f0 100644
--- a/speechx/speechx/frontend/audio/feature_pipeline.h
+++ b/speechx/speechx/frontend/audio/feature_pipeline.h
@@ -27,6 +27,7 @@
 
 // feature
 DECLARE_bool(use_fbank);
+DECLARE_bool(fill_zero);
 DECLARE_int32(num_bins);
 DECLARE_string(cmvn_file);
 
@@ -80,15 +81,18 @@ struct FeaturePipelineOptions {
 
         // assembler opts
         opts.assembler_opts.subsampling_rate = FLAGS_subsampling_rate;
-        LOG(INFO) << "subsampling rate: "
-                  << opts.assembler_opts.subsampling_rate;
         opts.assembler_opts.receptive_filed_length =
             FLAGS_receptive_field_length;
+        opts.assembler_opts.nnet_decoder_chunk = FLAGS_nnet_decoder_chunk;
+        opts.assembler_opts.fill_zero = FLAGS_fill_zero;
+        LOG(INFO) << "subsampling rate: "
+                  << opts.assembler_opts.subsampling_rate;
         LOG(INFO) << "nnet receptive filed length: "
                   << opts.assembler_opts.receptive_filed_length;
-        opts.assembler_opts.nnet_decoder_chunk = FLAGS_nnet_decoder_chunk;
         LOG(INFO) << "nnet chunk size: "
                   << opts.assembler_opts.nnet_decoder_chunk;
+        LOG(INFO) << "frontend fill zeros: "
+                  << opts.assembler_opts.fill_zero;
         return opts;
     }
 };
diff --git a/speechx/speechx/nnet/decodable.cc b/speechx/speechx/nnet/decodable.cc
index 6956a2cb8f371c1f90c368a70dae84982dda4d9d..a7de58b5831657faee498c3acc2ad9833dc25e83 100644
--- a/speechx/speechx/nnet/decodable.cc
+++ b/speechx/speechx/nnet/decodable.cc
@@ -114,7 +114,7 @@ bool Decodable::AdvanceChunk(kaldi::Vector<kaldi::BaseFloat>* logprobs,
 // read one frame likelihood
 bool Decodable::FrameLikelihood(int32 frame, vector<BaseFloat>* likelihood) {
     if (EnsureFrameHaveComputed(frame) == false) {
-        LOG(INFO) << "framelikehood exit.";
+        VLOG(1) << "framelikehood exit.";
         return false;
     }
 
diff --git a/speechx/speechx/recognizer/recognizer.h b/speechx/speechx/recognizer/recognizer.h
index 0402bcd3ccd5582b4b248c44a309c978046fad16..27f1228aeb35e67f94b61a2eddabf7847c31d6c0 100644
--- a/speechx/speechx/recognizer/recognizer.h
+++ b/speechx/speechx/recognizer/recognizer.h
@@ -38,6 +38,8 @@ struct RecognizerResource {
         resource.acoustic_scale = FLAGS_acoustic_scale;
         resource.feature_pipeline_opts =
             FeaturePipelineOptions::InitFromFlags();
+        resource.feature_pipeline_opts.assembler_opts.fill_zero = true;
+        LOG(INFO) << "ds2 need fill zero be true: " << resource.feature_pipeline_opts.assembler_opts.fill_zero;
         resource.model_opts = ModelOptions::InitFromFlags();
         resource.tlg_opts = TLGDecoderOptions::InitFromFlags();
         return resource;
diff --git a/speechx/speechx/recognizer/u2_recognizer.h b/speechx/speechx/recognizer/u2_recognizer.h
index 54f4d2580bb73b7d7a9de4d546bc189aac922417..4746d86f840e336bf257e3988699e0d74ad44f1c 100644
--- a/speechx/speechx/recognizer/u2_recognizer.h
+++ b/speechx/speechx/recognizer/u2_recognizer.h
@@ -101,6 +101,8 @@ struct U2RecognizerResource {
 
         resource.feature_pipeline_opts =
             ppspeech::FeaturePipelineOptions::InitFromFlags();
+        resource.feature_pipeline_opts.assembler_opts.fill_zero = false;
+        LOG(INFO) << "u2 need fill zero be false: " << resource.feature_pipeline_opts.assembler_opts.fill_zero;
         resource.model_opts = ppspeech::ModelOptions::InitFromFlags();
         resource.decoder_opts = ppspeech::DecodeOptions::InitFromFlags();
         return resource;
diff --git a/speechx/speechx/recognizer/u2_recognizer_main.cc b/speechx/speechx/recognizer/u2_recognizer_main.cc
index bfb37fb8ed440d0b886abe708336d496d8134f20..7e59d6cb0ee2eb5b7b490e073efa36e19710ed9c 100644
--- a/speechx/speechx/recognizer/u2_recognizer_main.cc
+++ b/speechx/speechx/recognizer/u2_recognizer_main.cc
@@ -85,9 +85,6 @@ int main(int argc, char* argv[]) {
             cnt++;
         }
         CHECK(sample_offset == tot_samples);
-        VLOG(1) << "num decode: " << cnt;
-
-        // recognizer.SetFinished();
 
         // second pass decoding
         recognizer.Rescoring();