diff --git a/speechx/CMakeLists.txt b/speechx/CMakeLists.txt
index f1330d1d..98d9e637 100644
--- a/speechx/CMakeLists.txt
+++ b/speechx/CMakeLists.txt
@@ -63,7 +63,8 @@ include(libsndfile)
 # include(boost) # not work
 set(boost_SOURCE_DIR ${fc_patch}/boost-src)
 set(BOOST_ROOT ${boost_SOURCE_DIR})
-# #find_package(boost REQUIRED PATHS ${BOOST_ROOT})
+include_directories(${boost_SOURCE_DIR})
+link_directories(${boost_SOURCE_DIR}/stage/lib)
 
 # Eigen
 include(eigen)
@@ -141,4 +142,4 @@ set(DEPS ${DEPS}
 set(SPEECHX_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/speechx)
 
 add_subdirectory(speechx)
-add_subdirectory(examples)
\ No newline at end of file
+add_subdirectory(examples)
diff --git a/speechx/examples/ds2_ol/CMakeLists.txt b/speechx/examples/ds2_ol/CMakeLists.txt
index 89cbd0ef..08c19484 100644
--- a/speechx/examples/ds2_ol/CMakeLists.txt
+++ b/speechx/examples/ds2_ol/CMakeLists.txt
@@ -2,4 +2,5 @@ cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
 add_subdirectory(feat)
 add_subdirectory(nnet)
-add_subdirectory(decoder)
\ No newline at end of file
+add_subdirectory(decoder)
+add_subdirectory(websocket)
diff --git a/speechx/examples/ds2_ol/aishell/path.sh b/speechx/examples/ds2_ol/aishell/path.sh
index 0a300f36..520129ea 100644
--- a/speechx/examples/ds2_ol/aishell/path.sh
+++ b/speechx/examples/ds2_ol/aishell/path.sh
@@ -1,6 +1,6 @@
 # This contains the locations of binarys build required for running the examples.
 
-SPEECHX_ROOT=$PWD/../../../
+SPEECHX_ROOT=$PWD/../../..
 SPEECHX_EXAMPLES=$SPEECHX_ROOT/build/examples
 
 SPEECHX_TOOLS=$SPEECHX_ROOT/tools
@@ -10,5 +10,5 @@ TOOLS_BIN=$SPEECHX_TOOLS/valgrind/install/bin
 
 export LC_AL=C
 
-SPEECHX_BIN=$SPEECHX_EXAMPLES/ds2_ol/decoder:$SPEECHX_EXAMPLES/ds2_ol/feat
-export PATH=$PATH:$SPEECHX_BIN:$TOOLS_BIN
\ No newline at end of file
+SPEECHX_BIN=$SPEECHX_EXAMPLES/ds2_ol/decoder:$SPEECHX_EXAMPLES/ds2_ol/feat:$SPEECHX_EXAMPLES/ds2_ol/websocket
+export PATH=$PATH:$SPEECHX_BIN:$TOOLS_BIN
diff --git a/speechx/examples/ds2_ol/aishell/run.sh b/speechx/examples/ds2_ol/aishell/run.sh
index 6a59ca9b..49fa5bc3 100755
--- a/speechx/examples/ds2_ol/aishell/run.sh
+++ b/speechx/examples/ds2_ol/aishell/run.sh
@@ -86,7 +86,7 @@ if [ $stage -le 2 ] && [ $stop_stage -ge 2 ];then
     ctc-prefix-beam-search-decoder-ol \
         --feature_rspecifier=scp:$data/split${nj}/JOB/feat.scp \
         --model_path=$model_dir/avg_1.jit.pdmodel \
-        --param_path=$model_dir/avg_1.jit.pdiparams \
+        --params_path=$model_dir/avg_1.jit.pdiparams \
         --model_output_names=softmax_0.tmp_0,tmp_5,concat_0.tmp_0,concat_1.tmp_0 \
         --dict_file=$vocb_dir/vocab.txt \
         --result_wspecifier=ark,t:$data/split${nj}/JOB/result
@@ -101,7 +101,7 @@ if [ $stage -le 3 ] && [ $stop_stage -ge 3 ];then
     ctc-prefix-beam-search-decoder-ol \
         --feature_rspecifier=scp:$data/split${nj}/JOB/feat.scp \
         --model_path=$model_dir/avg_1.jit.pdmodel \
-        --param_path=$model_dir/avg_1.jit.pdiparams \
+        --params_path=$model_dir/avg_1.jit.pdiparams \
         --model_output_names=softmax_0.tmp_0,tmp_5,concat_0.tmp_0,concat_1.tmp_0 \
         --dict_file=$vocb_dir/vocab.txt \
         --lm_path=$lm \
@@ -128,7 +128,7 @@ if [ $stage -le 4 ] && [ $stop_stage -ge 4 ]; then
     wfst-decoder-ol \
         --feature_rspecifier=scp:$data/split${nj}/JOB/feat.scp \
         --model_path=$model_dir/avg_1.jit.pdmodel \
-        --param_path=$model_dir/avg_1.jit.pdiparams \
+        --params_path=$model_dir/avg_1.jit.pdiparams \
         --word_symbol_table=$graph_dir/words.txt \
         --model_output_names=softmax_0.tmp_0,tmp_5,concat_0.tmp_0,concat_1.tmp_0 \
         --graph_path=$graph_dir/TLG.fst --max_active=7500 \
@@ -137,4 +137,4 @@ if [ $stage -le 4 ] && [ $stop_stage -ge 4 ]; then
 
     cat $data/split${nj}/*/result_tlg > $exp/${label_file}_tlg
     utils/compute-wer.py --char=1 --v=1 $exp/${label_file}_tlg $text > $exp/${wer}_tlg
-fi
\ No newline at end of file
+fi
diff --git a/speechx/examples/ds2_ol/aishell/websocket_client.sh b/speechx/examples/ds2_ol/aishell/websocket_client.sh
new file mode 100644
index 00000000..3c6b4e91
--- /dev/null
+++ b/speechx/examples/ds2_ol/aishell/websocket_client.sh
@@ -0,0 +1,37 @@
+#!/bin/bash
+set +x
+set -e
+
+. path.sh
+
+# 1. compile
+if [ ! -d ${SPEECHX_EXAMPLES} ]; then
+    pushd ${SPEECHX_ROOT} 
+    bash build.sh
+    popd
+fi
+
+# input
+mkdir -p data
+data=$PWD/data
+ckpt_dir=$data/model
+model_dir=$ckpt_dir/exp/deepspeech2_online/checkpoints/
+vocb_dir=$ckpt_dir/data/lang_char
+# output
+aishell_wav_scp=aishell_test.scp
+if [ ! -d $data/test ]; then
+    pushd $data
+    wget -c https://paddlespeech.bj.bcebos.com/s2t/paddle_asr_online/aishell_test.zip
+    unzip  aishell_test.zip
+    popd
+
+    realpath $data/test/*/*.wav > $data/wavlist
+    awk -F '/' '{ print $(NF) }' $data/wavlist | awk -F '.' '{ print $1 }' > $data/utt_id
+    paste $data/utt_id $data/wavlist > $data/$aishell_wav_scp
+fi
+
+export GLOG_logtostderr=1
+
+# websocket client
+websocket_client_main \
+    --wav_rspecifier=scp:$data/$aishell_wav_scp --streaming_chunk=0.36
diff --git a/speechx/examples/ds2_ol/aishell/websocket_server.sh b/speechx/examples/ds2_ol/aishell/websocket_server.sh
new file mode 100644
index 00000000..ea619d54
--- /dev/null
+++ b/speechx/examples/ds2_ol/aishell/websocket_server.sh
@@ -0,0 +1,66 @@
+#!/bin/bash
+set +x
+set -e
+
+. path.sh
+
+
+# 1. compile
+if [ ! -d ${SPEECHX_EXAMPLES} ]; then
+    pushd ${SPEECHX_ROOT} 
+    bash build.sh
+    popd
+fi
+
+# input
+mkdir -p data
+data=$PWD/data
+ckpt_dir=$data/model
+model_dir=$ckpt_dir/exp/deepspeech2_online/checkpoints/
+vocb_dir=$ckpt_dir/data/lang_char/
+
+# output
+aishell_wav_scp=aishell_test.scp
+if [ ! -d $data/test ]; then
+    pushd $data
+    wget -c https://paddlespeech.bj.bcebos.com/s2t/paddle_asr_online/aishell_test.zip
+    unzip  aishell_test.zip
+    popd
+
+    realpath $data/test/*/*.wav > $data/wavlist
+    awk -F '/' '{ print $(NF) }' $data/wavlist | awk -F '.' '{ print $1 }' > $data/utt_id
+    paste $data/utt_id $data/wavlist > $data/$aishell_wav_scp
+fi
+
+
+if [ ! -d $ckpt_dir ]; then
+    mkdir -p $ckpt_dir
+    wget -P $ckpt_dir -c https://paddlespeech.bj.bcebos.com/s2t/aishell/asr0/asr0_deepspeech2_online_aishell_ckpt_0.2.0.model.tar.gz
+    tar xzfv $ckpt_dir/asr0_deepspeech2_online_aishell_ckpt_0.2.0.model.tar.gz -C $ckpt_dir
+fi
+
+
+export GLOG_logtostderr=1
+
+# 3. gen cmvn 
+cmvn=$PWD/cmvn.ark
+cmvn-json2kaldi --json_file=$ckpt_dir/data/mean_std.json --cmvn_write_path=$cmvn
+
+text=$data/test/text
+graph_dir=./aishell_graph
+if [ ! -d $graph_dir ]; then
+    wget -c https://paddlespeech.bj.bcebos.com/s2t/paddle_asr_online/aishell_graph.zip
+    unzip aishell_graph.zip 
+fi
+
+# 5. test websocket server 
+websocket_server_main \
+    --cmvn_file=$cmvn \
+    --model_path=$model_dir/avg_1.jit.pdmodel \
+    --streaming_chunk=0.1 \
+    --convert2PCM32=true \
+    --params_path=$model_dir/avg_1.jit.pdiparams \
+    --word_symbol_table=$graph_dir/words.txt \
+    --model_output_names=softmax_0.tmp_0,tmp_5,concat_0.tmp_0,concat_1.tmp_0 \
+    --graph_path=$graph_dir/TLG.fst --max_active=7500 \
+    --acoustic_scale=1.2 
diff --git a/speechx/examples/ds2_ol/decoder/CMakeLists.txt b/speechx/examples/ds2_ol/decoder/CMakeLists.txt
index 6139ebfa..62dd6862 100644
--- a/speechx/examples/ds2_ol/decoder/CMakeLists.txt
+++ b/speechx/examples/ds2_ol/decoder/CMakeLists.txt
@@ -17,3 +17,6 @@ add_executable(${bin_name} ${CMAKE_CURRENT_SOURCE_DIR}/${bin_name}.cc)
 target_include_directories(${bin_name} PRIVATE ${SPEECHX_ROOT} ${SPEECHX_ROOT}/kaldi)
 target_link_libraries(${bin_name} PUBLIC nnet decoder fst utils gflags glog kaldi-base kaldi-matrix kaldi-util ${DEPS})
 
+add_executable(recognizer_test_main ${CMAKE_CURRENT_SOURCE_DIR}/recognizer_test_main.cc)
+target_include_directories(recognizer_test_main PRIVATE ${SPEECHX_ROOT} ${SPEECHX_ROOT}/kaldi)
+target_link_libraries(recognizer_test_main PUBLIC frontend kaldi-feat-common nnet decoder fst utils gflags glog kaldi-base kaldi-matrix kaldi-util kaldi-decoder ${DEPS})
diff --git a/speechx/examples/ds2_ol/decoder/ctc-prefix-beam-search-decoder-ol.cc b/speechx/examples/ds2_ol/decoder/ctc-prefix-beam-search-decoder-ol.cc
index 49d64b69..e145f6ee 100644
--- a/speechx/examples/ds2_ol/decoder/ctc-prefix-beam-search-decoder-ol.cc
+++ b/speechx/examples/ds2_ol/decoder/ctc-prefix-beam-search-decoder-ol.cc
@@ -34,12 +34,10 @@ DEFINE_int32(receptive_field_length,
 DEFINE_int32(downsampling_rate,
              4,
              "two CNN(kernel=5) module downsampling rate.");
-DEFINE_string(
-    model_input_names,
-    "audio_chunk,audio_chunk_lens,chunk_state_h_box,chunk_state_c_box",
-    "model input names");
 DEFINE_string(model_output_names,
-              "softmax_0.tmp_0,tmp_5,concat_0.tmp_0,concat_1.tmp_0",
+              "save_infer_model/scale_0.tmp_1,save_infer_model/"
+              "scale_1.tmp_1,save_infer_model/scale_2.tmp_1,save_infer_model/"
+              "scale_3.tmp_1",
               "model output names");
 DEFINE_string(model_cache_names, "5-1-1024,5-1-1024", "model cache names");
 
@@ -58,12 +56,11 @@ int main(int argc, char* argv[]) {
     kaldi::SequentialBaseFloatMatrixReader feature_reader(
         FLAGS_feature_rspecifier);
     kaldi::TokenWriter result_writer(FLAGS_result_wspecifier);
-
-    std::string model_graph = FLAGS_model_path;
+    std::string model_path = FLAGS_model_path;
     std::string model_params = FLAGS_param_path;
     std::string dict_file = FLAGS_dict_file;
     std::string lm_path = FLAGS_lm_path;
-    LOG(INFO) << "model path: " << model_graph;
+    LOG(INFO) << "model path: " << model_path;
     LOG(INFO) << "model param: " << model_params;
     LOG(INFO) << "dict path: " << dict_file;
     LOG(INFO) << "lm path: " << lm_path;
@@ -76,10 +73,9 @@ int main(int argc, char* argv[]) {
     ppspeech::CTCBeamSearch decoder(opts);
 
     ppspeech::ModelOptions model_opts;
-    model_opts.model_path = model_graph;
+    model_opts.model_path = model_path;
     model_opts.params_path = model_params;
     model_opts.cache_shape = FLAGS_model_cache_names;
-    model_opts.input_names = FLAGS_model_input_names;
     model_opts.output_names = FLAGS_model_output_names;
     std::shared_ptr<ppspeech::PaddleNnet> nnet(
         new ppspeech::PaddleNnet(model_opts));
@@ -125,7 +121,6 @@ int main(int argc, char* argv[]) {
             if (feature_chunk_size < receptive_field_length) break;
 
             int32 start = chunk_idx * chunk_stride;
-            int32 end = start + chunk_size;
 
             for (int row_id = 0; row_id < chunk_size; ++row_id) {
                 kaldi::SubVector<kaldi::BaseFloat> tmp(feature, start);
diff --git a/speechx/examples/ds2_ol/decoder/recognizer_test_main.cc b/speechx/examples/ds2_ol/decoder/recognizer_test_main.cc
new file mode 100644
index 00000000..198a8ec2
--- /dev/null
+++ b/speechx/examples/ds2_ol/decoder/recognizer_test_main.cc
@@ -0,0 +1,85 @@
+// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "decoder/recognizer.h"
+#include "decoder/param.h"
+#include "kaldi/feat/wave-reader.h"
+#include "kaldi/util/table-types.h"
+
+DEFINE_string(wav_rspecifier, "", "test feature rspecifier");
+DEFINE_string(result_wspecifier, "", "test result wspecifier");
+
+int main(int argc, char* argv[]) {
+    gflags::ParseCommandLineFlags(&argc, &argv, false);
+    google::InitGoogleLogging(argv[0]);
+
+    ppspeech::RecognizerResource resource = ppspeech::InitRecognizerResoure();
+    ppspeech::Recognizer recognizer(resource);
+
+    kaldi::SequentialTableReader<kaldi::WaveHolder> wav_reader(
+        FLAGS_wav_rspecifier);
+    kaldi::TokenWriter result_writer(FLAGS_result_wspecifier);
+    int sample_rate = 16000;
+    float streaming_chunk = FLAGS_streaming_chunk;
+    int chunk_sample_size = streaming_chunk * sample_rate;
+    LOG(INFO) << "sr: " << sample_rate;
+    LOG(INFO) << "chunk size (s): " << streaming_chunk;
+    LOG(INFO) << "chunk size (sample): " << chunk_sample_size;
+
+    int32 num_done = 0, num_err = 0;
+
+    for (; !wav_reader.Done(); wav_reader.Next()) {
+        std::string utt = wav_reader.Key();
+        const kaldi::WaveData& wave_data = wav_reader.Value();
+
+        int32 this_channel = 0;
+        kaldi::SubVector<kaldi::BaseFloat> waveform(wave_data.Data(),
+                                                    this_channel);
+        int tot_samples = waveform.Dim();
+        LOG(INFO) << "wav len (sample): " << tot_samples;
+
+        int sample_offset = 0;
+        std::vector<kaldi::Vector<BaseFloat>> feats;
+        int feature_rows = 0;
+        while (sample_offset < tot_samples) {
+            int cur_chunk_size =
+                std::min(chunk_sample_size, tot_samples - sample_offset);
+
+            kaldi::Vector<kaldi::BaseFloat> wav_chunk(cur_chunk_size);
+            for (int i = 0; i < cur_chunk_size; ++i) {
+                wav_chunk(i) = waveform(sample_offset + i);
+            }
+
+            recognizer.Accept(wav_chunk);
+            if (cur_chunk_size < chunk_sample_size) {
+                recognizer.SetFinished();
+            }
+            recognizer.Decode();
+
+            sample_offset += cur_chunk_size;
+        }
+        std::string result;
+        result = recognizer.GetFinalResult();
+        recognizer.Reset();
+        if (result.empty()) {
+            // the TokenWriter can not write empty string.
+            ++num_err;
+            KALDI_LOG << " the result of " << utt << " is empty";
+            continue;
+        }
+        KALDI_LOG << " the result of " << utt << " is " << result;
+        result_writer.Write(utt, result);
+        ++num_done;
+    }
+}
\ No newline at end of file
diff --git a/speechx/examples/ds2_ol/feat/cmvn-json2kaldi.cc b/speechx/examples/ds2_ol/feat/cmvn-json2kaldi.cc
index b8385664..0a9cfb06 100644
--- a/speechx/examples/ds2_ol/feat/cmvn-json2kaldi.cc
+++ b/speechx/examples/ds2_ol/feat/cmvn-json2kaldi.cc
@@ -73,9 +73,9 @@ int main(int argc, char* argv[]) {
         LOG(INFO) << "cmvn stats have write into: " << FLAGS_cmvn_write_path;
         LOG(INFO) << "Binary: " << FLAGS_binary;
     } catch (simdjson::simdjson_error& err) {
-        LOG(ERR) << err.what();
+        LOG(ERROR) << err.what();
     }
 
 
     return 0;
-}
\ No newline at end of file
+}
diff --git a/speechx/examples/ds2_ol/feat/linear-spectrogram-wo-db-norm-ol.cc b/speechx/examples/ds2_ol/feat/linear-spectrogram-wo-db-norm-ol.cc
index 27ca6f9f..0d10bd30 100644
--- a/speechx/examples/ds2_ol/feat/linear-spectrogram-wo-db-norm-ol.cc
+++ b/speechx/examples/ds2_ol/feat/linear-spectrogram-wo-db-norm-ol.cc
@@ -32,7 +32,6 @@ DEFINE_string(feature_wspecifier, "", "output feats wspecifier");
 DEFINE_string(cmvn_file, "./cmvn.ark", "read cmvn");
 DEFINE_double(streaming_chunk, 0.36, "streaming feature chunk size");
 
-
 int main(int argc, char* argv[]) {
     gflags::ParseCommandLineFlags(&argc, &argv, false);
     google::InitGoogleLogging(argv[0]);
@@ -66,7 +65,8 @@ int main(int argc, char* argv[]) {
     std::unique_ptr<ppspeech::FrontendInterface> cmvn(
         new ppspeech::CMVN(FLAGS_cmvn_file, std::move(linear_spectrogram)));
 
-    ppspeech::FeatureCache feature_cache(kint16max, std::move(cmvn));
+    ppspeech::FeatureCacheOptions feat_cache_opts;
+    ppspeech::FeatureCache feature_cache(feat_cache_opts, std::move(cmvn));
     LOG(INFO) << "feat dim: " << feature_cache.Dim();
 
     int sample_rate = 16000;
diff --git a/speechx/examples/ds2_ol/websocket/CMakeLists.txt b/speechx/examples/ds2_ol/websocket/CMakeLists.txt
new file mode 100644
index 00000000..754b528e
--- /dev/null
+++ b/speechx/examples/ds2_ol/websocket/CMakeLists.txt
@@ -0,0 +1,10 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+add_executable(websocket_server_main ${CMAKE_CURRENT_SOURCE_DIR}/websocket_server_main.cc)
+target_include_directories(websocket_server_main PRIVATE ${SPEECHX_ROOT} ${SPEECHX_ROOT}/kaldi)
+target_link_libraries(websocket_server_main PUBLIC frontend kaldi-feat-common nnet decoder fst utils gflags glog kaldi-base kaldi-matrix kaldi-util kaldi-decoder websocket ${DEPS})
+
+add_executable(websocket_client_main ${CMAKE_CURRENT_SOURCE_DIR}/websocket_client_main.cc)
+target_include_directories(websocket_client_main PRIVATE ${SPEECHX_ROOT} ${SPEECHX_ROOT}/kaldi)
+target_link_libraries(websocket_client_main PUBLIC frontend kaldi-feat-common nnet decoder fst utils gflags glog kaldi-base kaldi-matrix kaldi-util kaldi-decoder websocket ${DEPS})
+
diff --git a/speechx/examples/ds2_ol/websocket/websocket_client_main.cc b/speechx/examples/ds2_ol/websocket/websocket_client_main.cc
new file mode 100644
index 00000000..68ea898a
--- /dev/null
+++ b/speechx/examples/ds2_ol/websocket/websocket_client_main.cc
@@ -0,0 +1,82 @@
+// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "websocket/websocket_client.h"
+#include "kaldi/feat/wave-reader.h"
+#include "kaldi/util/kaldi-io.h"
+#include "kaldi/util/table-types.h"
+
+DEFINE_string(host, "127.0.0.1", "host of websocket server");
+DEFINE_int32(port, 201314, "port of websocket server");
+DEFINE_string(wav_rspecifier, "", "test wav scp path");
+DEFINE_double(streaming_chunk, 0.1, "streaming feature chunk size");
+
+using kaldi::int16;
+int main(int argc, char* argv[]) {
+    gflags::ParseCommandLineFlags(&argc, &argv, false);
+    google::InitGoogleLogging(argv[0]);
+    ppspeech::WebSocketClient client(FLAGS_host, FLAGS_port);
+
+    kaldi::SequentialTableReader<kaldi::WaveHolder> wav_reader(
+        FLAGS_wav_rspecifier);
+
+    const int sample_rate = 16000;
+    const float streaming_chunk = FLAGS_streaming_chunk;
+    const int chunk_sample_size = streaming_chunk * sample_rate;
+
+    for (; !wav_reader.Done(); wav_reader.Next()) {
+        client.SendStartSignal();
+        std::string utt = wav_reader.Key();
+        const kaldi::WaveData& wave_data = wav_reader.Value();
+        CHECK_EQ(wave_data.SampFreq(), sample_rate);
+
+        int32 this_channel = 0;
+        kaldi::SubVector<kaldi::BaseFloat> waveform(wave_data.Data(),
+                                                    this_channel);
+        const int tot_samples = waveform.Dim();
+        int sample_offset = 0;
+
+        while (sample_offset < tot_samples) {
+            int cur_chunk_size =
+                std::min(chunk_sample_size, tot_samples - sample_offset);
+
+            std::vector<int16> wav_chunk(cur_chunk_size);
+            for (int i = 0; i < cur_chunk_size; ++i) {
+                wav_chunk[i] = static_cast<int16>(waveform(sample_offset + i));
+            }
+            client.SendBinaryData(wav_chunk.data(),
+                                  wav_chunk.size() * sizeof(int16));
+
+
+            sample_offset += cur_chunk_size;
+            LOG(INFO) << "Send " << cur_chunk_size << " samples";
+            std::this_thread::sleep_for(
+                std::chrono::milliseconds(static_cast<int>(1 * 1000)));
+
+            if (cur_chunk_size < chunk_sample_size) {
+                client.SendEndSignal();
+            }
+        }
+
+        while (!client.Done()) {
+        }
+        std::string result = client.GetResult();
+        LOG(INFO) << "utt: " << utt << " " << result;
+
+
+        client.Join();
+        return 0;
+    }
+    return 0;
+}
diff --git a/speechx/examples/ds2_ol/websocket/websocket_server_main.cc b/speechx/examples/ds2_ol/websocket/websocket_server_main.cc
new file mode 100644
index 00000000..43cbd6bb
--- /dev/null
+++ b/speechx/examples/ds2_ol/websocket/websocket_server_main.cc
@@ -0,0 +1,30 @@
+// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "websocket/websocket_server.h"
+#include "decoder/param.h"
+
+DEFINE_int32(port, 201314, "websocket listening port");
+
+int main(int argc, char *argv[]) {
+    gflags::ParseCommandLineFlags(&argc, &argv, false);
+    google::InitGoogleLogging(argv[0]);
+
+    ppspeech::RecognizerResource resource = ppspeech::InitRecognizerResoure();
+
+    ppspeech::WebSocketServer server(FLAGS_port, resource);
+    LOG(INFO) << "Listening at port " << FLAGS_port;
+    server.Start();
+    return 0;
+}
diff --git a/speechx/speechx/CMakeLists.txt b/speechx/speechx/CMakeLists.txt
index 225abee7..b4da095d 100644
--- a/speechx/speechx/CMakeLists.txt
+++ b/speechx/speechx/CMakeLists.txt
@@ -30,4 +30,10 @@ include_directories(
 ${CMAKE_CURRENT_SOURCE_DIR}
 ${CMAKE_CURRENT_SOURCE_DIR}/decoder
 )
-add_subdirectory(decoder)
\ No newline at end of file
+add_subdirectory(decoder)
+
+include_directories(
+${CMAKE_CURRENT_SOURCE_DIR}
+${CMAKE_CURRENT_SOURCE_DIR}/websocket
+)
+add_subdirectory(websocket)
diff --git a/speechx/speechx/base/common.h b/speechx/speechx/base/common.h
index 7502bc5e..a9303cbb 100644
--- a/speechx/speechx/base/common.h
+++ b/speechx/speechx/base/common.h
@@ -28,8 +28,10 @@
 #include <sstream>
 #include <stack>
 #include <string>
+#include <thread>
 #include <unordered_map>
 #include <unordered_set>
+#include <utility>
 #include <vector>
 
 #include "base/basic_types.h"
diff --git a/speechx/speechx/decoder/CMakeLists.txt b/speechx/speechx/decoder/CMakeLists.txt
index ee0863fd..06bf4020 100644
--- a/speechx/speechx/decoder/CMakeLists.txt
+++ b/speechx/speechx/decoder/CMakeLists.txt
@@ -7,5 +7,6 @@ add_library(decoder STATIC
   ctc_decoders/path_trie.cpp
   ctc_decoders/scorer.cpp
   ctc_tlg_decoder.cc
+  recognizer.cc
 )
-target_link_libraries(decoder PUBLIC kenlm utils fst)
+target_link_libraries(decoder PUBLIC kenlm utils fst frontend nnet kaldi-decoder)
diff --git a/speechx/speechx/decoder/ctc_tlg_decoder.cc b/speechx/speechx/decoder/ctc_tlg_decoder.cc
index 5365e709..7b720e7b 100644
--- a/speechx/speechx/decoder/ctc_tlg_decoder.cc
+++ b/speechx/speechx/decoder/ctc_tlg_decoder.cc
@@ -33,7 +33,6 @@ void TLGDecoder::InitDecoder() {
 void TLGDecoder::AdvanceDecode(
     const std::shared_ptr<kaldi::DecodableInterface>& decodable) {
     while (!decodable->IsLastFrame(frame_decoded_size_)) {
-        LOG(INFO) << "num frame decode: " << frame_decoded_size_;
         AdvanceDecoding(decodable.get());
     }
 }
@@ -63,4 +62,4 @@ std::string TLGDecoder::GetFinalBestPath() {
     }
     return words;
 }
-}
\ No newline at end of file
+}
diff --git a/speechx/speechx/decoder/param.h b/speechx/speechx/decoder/param.h
new file mode 100644
index 00000000..cd50ef53
--- /dev/null
+++ b/speechx/speechx/decoder/param.h
@@ -0,0 +1,94 @@
+// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "base/common.h"
+
+#include "decoder/ctc_beam_search_decoder.h"
+#include "decoder/ctc_tlg_decoder.h"
+#include "frontend/audio/feature_pipeline.h"
+
+DEFINE_string(cmvn_file, "", "read cmvn");
+DEFINE_double(streaming_chunk, 0.1, "streaming feature chunk size");
+DEFINE_bool(convert2PCM32, true, "audio convert to pcm32");
+DEFINE_string(model_path, "avg_1.jit.pdmodel", "paddle nnet model");
+DEFINE_string(params_path, "avg_1.jit.pdiparams", "paddle nnet model param");
+DEFINE_string(word_symbol_table, "words.txt", "word symbol table");
+DEFINE_string(graph_path, "TLG", "decoder graph");
+DEFINE_double(acoustic_scale, 1.0, "acoustic scale");
+DEFINE_int32(max_active, 7500, "max active");
+DEFINE_double(beam, 15.0, "decoder beam");
+DEFINE_double(lattice_beam, 7.5, "decoder beam");
+DEFINE_int32(receptive_field_length,
+             7,
+             "receptive field of two CNN(kernel=5) downsampling module.");
+DEFINE_int32(downsampling_rate,
+             4,
+             "two CNN(kernel=5) module downsampling rate.");
+DEFINE_string(model_output_names,
+              "save_infer_model/scale_0.tmp_1,save_infer_model/"
+              "scale_1.tmp_1,save_infer_model/scale_2.tmp_1,save_infer_model/"
+              "scale_3.tmp_1",
+              "model output names");
+DEFINE_string(model_cache_names, "5-1-1024,5-1-1024", "model cache names");
+
+namespace ppspeech {
+// todo refactor later
+FeaturePipelineOptions InitFeaturePipelineOptions() {
+    FeaturePipelineOptions opts;
+    opts.cmvn_file = FLAGS_cmvn_file;
+    opts.linear_spectrogram_opts.streaming_chunk = FLAGS_streaming_chunk;
+    opts.convert2PCM32 = FLAGS_convert2PCM32;
+    kaldi::FrameExtractionOptions frame_opts;
+    frame_opts.frame_length_ms = 20;
+    frame_opts.frame_shift_ms = 10;
+    frame_opts.remove_dc_offset = false;
+    frame_opts.window_type = "hanning";
+    frame_opts.preemph_coeff = 0.0;
+    frame_opts.dither = 0.0;
+    opts.linear_spectrogram_opts.frame_opts = frame_opts;
+    opts.feature_cache_opts.frame_chunk_size = FLAGS_receptive_field_length;
+    opts.feature_cache_opts.frame_chunk_stride = FLAGS_downsampling_rate;
+    return opts;
+}
+
+ModelOptions InitModelOptions() {
+    ModelOptions model_opts;
+    model_opts.model_path = FLAGS_model_path;
+    model_opts.params_path = FLAGS_params_path;
+    model_opts.cache_shape = FLAGS_model_cache_names;
+    model_opts.output_names = FLAGS_model_output_names;
+    return model_opts;
+}
+
+TLGDecoderOptions InitDecoderOptions() {
+    TLGDecoderOptions decoder_opts;
+    decoder_opts.word_symbol_table = FLAGS_word_symbol_table;
+    decoder_opts.fst_path = FLAGS_graph_path;
+    decoder_opts.opts.max_active = FLAGS_max_active;
+    decoder_opts.opts.beam = FLAGS_beam;
+    decoder_opts.opts.lattice_beam = FLAGS_lattice_beam;
+    return decoder_opts;
+}
+
+RecognizerResource InitRecognizerResoure() {
+    RecognizerResource resource;
+    resource.acoustic_scale = FLAGS_acoustic_scale;
+    resource.feature_pipeline_opts = InitFeaturePipelineOptions();
+    resource.model_opts = InitModelOptions();
+    resource.tlg_opts = InitDecoderOptions();
+    return resource;
+}
+}
\ No newline at end of file
diff --git a/speechx/speechx/decoder/recognizer.cc b/speechx/speechx/decoder/recognizer.cc
new file mode 100644
index 00000000..2c90ada9
--- /dev/null
+++ b/speechx/speechx/decoder/recognizer.cc
@@ -0,0 +1,60 @@
+// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "decoder/recognizer.h"
+
+namespace ppspeech {
+
+using kaldi::Vector;
+using kaldi::VectorBase;
+using kaldi::BaseFloat;
+using std::vector;
+using kaldi::SubVector;
+using std::unique_ptr;
+
+Recognizer::Recognizer(const RecognizerResource& resource) {
+    // resource_ = resource;
+    const FeaturePipelineOptions& feature_opts = resource.feature_pipeline_opts;
+    feature_pipeline_.reset(new FeaturePipeline(feature_opts));
+    std::shared_ptr<PaddleNnet> nnet(new PaddleNnet(resource.model_opts));
+    BaseFloat ac_scale = resource.acoustic_scale;
+    decodable_.reset(new Decodable(nnet, feature_pipeline_, ac_scale));
+    decoder_.reset(new TLGDecoder(resource.tlg_opts));
+    input_finished_ = false;
+}
+
+void Recognizer::Accept(const Vector<BaseFloat>& waves) {
+    feature_pipeline_->Accept(waves);
+}
+
+void Recognizer::Decode() { decoder_->AdvanceDecode(decodable_); }
+
+std::string Recognizer::GetFinalResult() {
+    return decoder_->GetFinalBestPath();
+}
+
+void Recognizer::SetFinished() {
+    feature_pipeline_->SetFinished();
+    input_finished_ = true;
+}
+
+bool Recognizer::IsFinished() { return input_finished_; }
+
+void Recognizer::Reset() {
+    feature_pipeline_->Reset();
+    decodable_->Reset();
+    decoder_->Reset();
+}
+
+}  // namespace ppspeech
\ No newline at end of file
diff --git a/speechx/speechx/decoder/recognizer.h b/speechx/speechx/decoder/recognizer.h
new file mode 100644
index 00000000..9a7e7d11
--- /dev/null
+++ b/speechx/speechx/decoder/recognizer.h
@@ -0,0 +1,59 @@
+// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// todo refactor later (SGoat)
+
+#pragma once
+
+#include "decoder/ctc_beam_search_decoder.h"
+#include "decoder/ctc_tlg_decoder.h"
+#include "frontend/audio/feature_pipeline.h"
+#include "nnet/decodable.h"
+#include "nnet/paddle_nnet.h"
+
+namespace ppspeech {
+
+struct RecognizerResource {
+    FeaturePipelineOptions feature_pipeline_opts;
+    ModelOptions model_opts;
+    TLGDecoderOptions tlg_opts;
+    //    CTCBeamSearchOptions beam_search_opts;
+    kaldi::BaseFloat acoustic_scale;
+    RecognizerResource()
+        : acoustic_scale(1.0),
+          feature_pipeline_opts(),
+          model_opts(),
+          tlg_opts() {}
+};
+
+class Recognizer {
+  public:
+    explicit Recognizer(const RecognizerResource& resouce);
+    void Accept(const kaldi::Vector<kaldi::BaseFloat>& waves);
+    void Decode();
+    std::string GetFinalResult();
+    void SetFinished();
+    bool IsFinished();
+    void Reset();
+
+  private:
+    // std::shared_ptr<RecognizerResource> resource_;
+    // RecognizerResource resource_;
+    std::shared_ptr<FeaturePipeline> feature_pipeline_;
+    std::shared_ptr<Decodable> decodable_;
+    std::unique_ptr<TLGDecoder> decoder_;
+    bool input_finished_;
+};
+
+}  // namespace ppspeech
\ No newline at end of file
diff --git a/speechx/speechx/frontend/audio/CMakeLists.txt b/speechx/speechx/frontend/audio/CMakeLists.txt
index 35243b6e..2d20edf7 100644
--- a/speechx/speechx/frontend/audio/CMakeLists.txt
+++ b/speechx/speechx/frontend/audio/CMakeLists.txt
@@ -6,6 +6,7 @@ add_library(frontend STATIC
   linear_spectrogram.cc
   audio_cache.cc
   feature_cache.cc
+  feature_pipeline.cc
 )
 
-target_link_libraries(frontend PUBLIC kaldi-matrix)
\ No newline at end of file
+target_link_libraries(frontend PUBLIC kaldi-matrix kaldi-feat-common)
diff --git a/speechx/speechx/frontend/audio/audio_cache.cc b/speechx/speechx/frontend/audio/audio_cache.cc
index 50aca4fb..e8af6668 100644
--- a/speechx/speechx/frontend/audio/audio_cache.cc
+++ b/speechx/speechx/frontend/audio/audio_cache.cc
@@ -41,7 +41,7 @@ void AudioCache::Accept(const VectorBase<BaseFloat>& waves) {
         ready_feed_condition_.wait(lock);
     }
     for (size_t idx = 0; idx < waves.Dim(); ++idx) {
-        int32 buffer_idx = (idx + offset_) % ring_buffer_.size();
+        int32 buffer_idx = (idx + offset_ + size_) % ring_buffer_.size();
         ring_buffer_[buffer_idx] = waves(idx);
         if (convert2PCM32_)
             ring_buffer_[buffer_idx] = Convert2PCM32(waves(idx));
diff --git a/speechx/speechx/frontend/audio/audio_cache.h b/speechx/speechx/frontend/audio/audio_cache.h
index adef1239..a681ef09 100644
--- a/speechx/speechx/frontend/audio/audio_cache.h
+++ b/speechx/speechx/frontend/audio/audio_cache.h
@@ -24,7 +24,7 @@ namespace ppspeech {
 class AudioCache : public FrontendInterface {
   public:
     explicit AudioCache(int buffer_size = 1000 * kint16max,
-                        bool convert2PCM32 = false);
+                        bool convert2PCM32 = true);
 
     virtual void Accept(const kaldi::VectorBase<BaseFloat>& waves);
 
diff --git a/speechx/speechx/frontend/audio/feature_cache.cc b/speechx/speechx/frontend/audio/feature_cache.cc
index 3f7f6502..b5768460 100644
--- a/speechx/speechx/frontend/audio/feature_cache.cc
+++ b/speechx/speechx/frontend/audio/feature_cache.cc
@@ -23,10 +23,13 @@ using std::vector;
 using kaldi::SubVector;
 using std::unique_ptr;
 
-FeatureCache::FeatureCache(int max_size,
+FeatureCache::FeatureCache(FeatureCacheOptions opts,
                            unique_ptr<FrontendInterface> base_extractor) {
-    max_size_ = max_size;
+    max_size_ = opts.max_size;
+    frame_chunk_stride_ = opts.frame_chunk_stride;
+    frame_chunk_size_ = opts.frame_chunk_size;
     base_extractor_ = std::move(base_extractor);
+    dim_ = base_extractor_->Dim();
 }
 
 void FeatureCache::Accept(const kaldi::VectorBase<kaldi::BaseFloat>& inputs) {
@@ -44,13 +47,14 @@ bool FeatureCache::Read(kaldi::Vector<kaldi::BaseFloat>* feats) {
 
     std::unique_lock<std::mutex> lock(mutex_);
     while (cache_.empty() && base_extractor_->IsFinished() == false) {
-        ready_read_condition_.wait(lock);
-        BaseFloat elapsed = timer.Elapsed() * 1000;
-        // todo replace 1.0 with timeout_
-        if (elapsed > 1.0) {
+        // todo refactor: wait
+        // ready_read_condition_.wait(lock);
+        int32 elapsed = static_cast<int32>(timer.Elapsed() * 1000);
+        // todo replace 1 with timeout_, 1 ms
+        if (elapsed > 1) {
             return false;
         }
-        usleep(1000);  // sleep 1 ms
+        usleep(100);  // sleep 0.1 ms
     }
     if (cache_.empty()) return false;
     feats->Resize(cache_.front().Dim());
@@ -63,25 +67,41 @@ bool FeatureCache::Read(kaldi::Vector<kaldi::BaseFloat>* feats) {
 // read all data from base_feature_extractor_ into cache_
 bool FeatureCache::Compute() {
     // compute and feed
-    Vector<BaseFloat> feature_chunk;
-    bool result = base_extractor_->Read(&feature_chunk);
+    Vector<BaseFloat> feature;
+    bool result = base_extractor_->Read(&feature);
+    if (result == false || feature.Dim() == 0) return false;
+    int32 joint_len = feature.Dim() + remained_feature_.Dim();
+    int32 num_chunk =
+        ((joint_len / dim_) - frame_chunk_size_) / frame_chunk_stride_ + 1;
 
-    std::unique_lock<std::mutex> lock(mutex_);
-    while (cache_.size() >= max_size_) {
-        ready_feed_condition_.wait(lock);
-    }
+    Vector<BaseFloat> joint_feature(joint_len);
+    joint_feature.Range(0, remained_feature_.Dim())
+        .CopyFromVec(remained_feature_);
+    joint_feature.Range(remained_feature_.Dim(), feature.Dim())
+        .CopyFromVec(feature);
 
-    // feed cache
-    if (feature_chunk.Dim() != 0) {
+    for (int chunk_idx = 0; chunk_idx < num_chunk; ++chunk_idx) {
+        int32 start = chunk_idx * frame_chunk_stride_ * dim_;
+        Vector<BaseFloat> feature_chunk(frame_chunk_size_ * dim_);
+        SubVector<BaseFloat> tmp(joint_feature.Data() + start,
+                                 frame_chunk_size_ * dim_);
+        feature_chunk.CopyFromVec(tmp);
+
+        std::unique_lock<std::mutex> lock(mutex_);
+        while (cache_.size() >= max_size_) {
+            ready_feed_condition_.wait(lock);
+        }
+
+        // feed cache
         cache_.push(feature_chunk);
+        ready_read_condition_.notify_one();
     }
-    ready_read_condition_.notify_one();
+    int32 remained_feature_len =
+        joint_len - num_chunk * frame_chunk_stride_ * dim_;
+    remained_feature_.Resize(remained_feature_len);
+    remained_feature_.CopyFromVec(joint_feature.Range(
+        frame_chunk_stride_ * num_chunk * dim_, remained_feature_len));
     return result;
 }
 
-void Reset() {
-    // std::lock_guard<std::mutex> lock(mutex_);
-    return;
-}
-
 }  // namespace ppspeech
\ No newline at end of file
diff --git a/speechx/speechx/frontend/audio/feature_cache.h b/speechx/speechx/frontend/audio/feature_cache.h
index 99961b5e..607f72c0 100644
--- a/speechx/speechx/frontend/audio/feature_cache.h
+++ b/speechx/speechx/frontend/audio/feature_cache.h
@@ -19,10 +19,18 @@
 
 namespace ppspeech {
 
+struct FeatureCacheOptions {
+    int32 max_size;
+    int32 frame_chunk_size;
+    int32 frame_chunk_stride;
+    FeatureCacheOptions()
+        : max_size(kint16max), frame_chunk_size(1), frame_chunk_stride(1) {}
+};
+
 class FeatureCache : public FrontendInterface {
   public:
     explicit FeatureCache(
-        int32 max_size = kint16max,
+        FeatureCacheOptions opts,
         std::unique_ptr<FrontendInterface> base_extractor = NULL);
 
     // Feed feats or waves
@@ -32,12 +40,15 @@ class FeatureCache : public FrontendInterface {
     virtual bool Read(kaldi::Vector<kaldi::BaseFloat>* feats);
 
     // feat dim
-    virtual size_t Dim() const { return base_extractor_->Dim(); }
+    virtual size_t Dim() const { return dim_; }
 
     virtual void SetFinished() {
+        // std::unique_lock<std::mutex> lock(mutex_);
         base_extractor_->SetFinished();
+        LOG(INFO) << "set finished";
         // read the last chunk data
         Compute();
+        // ready_feed_condition_.notify_one();
     }
 
     virtual bool IsFinished() const { return base_extractor_->IsFinished(); }
@@ -52,9 +63,13 @@ class FeatureCache : public FrontendInterface {
   private:
     bool Compute();
 
+    int32 dim_;
     size_t max_size_;
-    std::unique_ptr<FrontendInterface> base_extractor_;
+    int32 frame_chunk_size_;
+    int32 frame_chunk_stride_;
 
+    kaldi::Vector<kaldi::BaseFloat> remained_feature_;
+    std::unique_ptr<FrontendInterface> base_extractor_;
     std::mutex mutex_;
     std::queue<kaldi::Vector<BaseFloat>> cache_;
     std::condition_variable ready_feed_condition_;
diff --git a/speechx/speechx/frontend/audio/feature_pipeline.cc b/speechx/speechx/frontend/audio/feature_pipeline.cc
new file mode 100644
index 00000000..86eca2e0
--- /dev/null
+++ b/speechx/speechx/frontend/audio/feature_pipeline.cc
@@ -0,0 +1,36 @@
+// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "frontend/audio/feature_pipeline.h"
+
+namespace ppspeech {
+
+using std::unique_ptr;
+
+FeaturePipeline::FeaturePipeline(const FeaturePipelineOptions& opts) {
+    unique_ptr<FrontendInterface> data_source(
+        new ppspeech::AudioCache(1000 * kint16max, opts.convert2PCM32));
+
+    unique_ptr<FrontendInterface> linear_spectrogram(
+        new ppspeech::LinearSpectrogram(opts.linear_spectrogram_opts,
+                                        std::move(data_source)));
+
+    unique_ptr<FrontendInterface> cmvn(
+        new ppspeech::CMVN(opts.cmvn_file, std::move(linear_spectrogram)));
+
+    base_extractor_.reset(
+        new ppspeech::FeatureCache(opts.feature_cache_opts, std::move(cmvn)));
+}
+
+}  // ppspeech
\ No newline at end of file
diff --git a/speechx/speechx/frontend/audio/feature_pipeline.h b/speechx/speechx/frontend/audio/feature_pipeline.h
new file mode 100644
index 00000000..7bd6c84f
--- /dev/null
+++ b/speechx/speechx/frontend/audio/feature_pipeline.h
@@ -0,0 +1,57 @@
+// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// todo refactor later (SGoat)
+
+#pragma once
+
+#include "frontend/audio/audio_cache.h"
+#include "frontend/audio/data_cache.h"
+#include "frontend/audio/feature_cache.h"
+#include "frontend/audio/frontend_itf.h"
+#include "frontend/audio/linear_spectrogram.h"
+#include "frontend/audio/normalizer.h"
+
+namespace ppspeech {
+
+struct FeaturePipelineOptions {
+    std::string cmvn_file;
+    bool convert2PCM32;
+    LinearSpectrogramOptions linear_spectrogram_opts;
+    FeatureCacheOptions feature_cache_opts;
+    FeaturePipelineOptions()
+        : cmvn_file(""),
+          convert2PCM32(false),
+          linear_spectrogram_opts(),
+          feature_cache_opts() {}
+};
+
+class FeaturePipeline : public FrontendInterface {
+  public:
+    explicit FeaturePipeline(const FeaturePipelineOptions& opts);
+    virtual void Accept(const kaldi::VectorBase<kaldi::BaseFloat>& waves) {
+        base_extractor_->Accept(waves);
+    }
+    virtual bool Read(kaldi::Vector<kaldi::BaseFloat>* feats) {
+        return base_extractor_->Read(feats);
+    }
+    virtual size_t Dim() const { return base_extractor_->Dim(); }
+    virtual void SetFinished() { base_extractor_->SetFinished(); }
+    virtual bool IsFinished() const { return base_extractor_->IsFinished(); }
+    virtual void Reset() { base_extractor_->Reset(); }
+
+  private:
+    std::unique_ptr<FrontendInterface> base_extractor_;
+};
+}
\ No newline at end of file
diff --git a/speechx/speechx/frontend/audio/linear_spectrogram.cc b/speechx/speechx/frontend/audio/linear_spectrogram.cc
index d6ae3d01..9ef5e766 100644
--- a/speechx/speechx/frontend/audio/linear_spectrogram.cc
+++ b/speechx/speechx/frontend/audio/linear_spectrogram.cc
@@ -52,16 +52,16 @@ bool LinearSpectrogram::Read(Vector<BaseFloat>* feats) {
     if (flag == false || input_feats.Dim() == 0) return false;
 
     int32 feat_len = input_feats.Dim();
-    int32 left_len = reminded_wav_.Dim();
+    int32 left_len = remained_wav_.Dim();
     Vector<BaseFloat> waves(feat_len + left_len);
-    waves.Range(0, left_len).CopyFromVec(reminded_wav_);
+    waves.Range(0, left_len).CopyFromVec(remained_wav_);
     waves.Range(left_len, feat_len).CopyFromVec(input_feats);
     Compute(waves, feats);
     int32 frame_shift = opts_.frame_opts.WindowShift();
     int32 num_frames = kaldi::NumFrames(waves.Dim(), opts_.frame_opts);
     int32 left_samples = waves.Dim() - frame_shift * num_frames;
-    reminded_wav_.Resize(left_samples);
-    reminded_wav_.CopyFromVec(
+    remained_wav_.Resize(left_samples);
+    remained_wav_.CopyFromVec(
         waves.Range(frame_shift * num_frames, left_samples));
     return true;
 }
diff --git a/speechx/speechx/frontend/audio/linear_spectrogram.h b/speechx/speechx/frontend/audio/linear_spectrogram.h
index 689ec2c4..2764b7cf 100644
--- a/speechx/speechx/frontend/audio/linear_spectrogram.h
+++ b/speechx/speechx/frontend/audio/linear_spectrogram.h
@@ -25,12 +25,12 @@ struct LinearSpectrogramOptions {
     kaldi::FrameExtractionOptions frame_opts;
     kaldi::BaseFloat streaming_chunk;  // second
 
-    LinearSpectrogramOptions() : streaming_chunk(0.36), frame_opts() {}
+    LinearSpectrogramOptions() : streaming_chunk(0.1), frame_opts() {}
 
     void Register(kaldi::OptionsItf* opts) {
         opts->Register("streaming-chunk",
                        &streaming_chunk,
-                       "streaming chunk size, default: 0.36 sec");
+                       "streaming chunk size, default: 0.1 sec");
         frame_opts.Register(opts);
     }
 };
@@ -48,7 +48,7 @@ class LinearSpectrogram : public FrontendInterface {
     virtual bool IsFinished() const { return base_extractor_->IsFinished(); }
     virtual void Reset() {
         base_extractor_->Reset();
-        reminded_wav_.Resize(0);
+        remained_wav_.Resize(0);
     }
 
   private:
@@ -60,7 +60,7 @@ class LinearSpectrogram : public FrontendInterface {
     kaldi::BaseFloat hanning_window_energy_;
     LinearSpectrogramOptions opts_;
     std::unique_ptr<FrontendInterface> base_extractor_;
-    kaldi::Vector<kaldi::BaseFloat> reminded_wav_;
+    kaldi::Vector<kaldi::BaseFloat> remained_wav_;
     int chunk_sample_size_;
     DISALLOW_COPY_AND_ASSIGN(LinearSpectrogram);
 };
diff --git a/speechx/speechx/nnet/decodable.cc b/speechx/speechx/nnet/decodable.cc
index 3f5dadd2..465f64a9 100644
--- a/speechx/speechx/nnet/decodable.cc
+++ b/speechx/speechx/nnet/decodable.cc
@@ -78,7 +78,6 @@ bool Decodable::AdvanceChunk() {
     }
     int32 nnet_dim = 0;
     Vector<BaseFloat> inferences;
-    Matrix<BaseFloat> nnet_cache_tmp;
     nnet_->FeedForward(features, frontend_->Dim(), &inferences, &nnet_dim);
     nnet_cache_.Resize(inferences.Dim() / nnet_dim, nnet_dim);
     nnet_cache_.CopyRowsFromVec(inferences);