Add the Speech-To-Text in introduction.md

docs/source/introduction.md

@@ -6,8 +6,31 @@ PaddleSpeech is an open-source toolkit on PaddlePaddle platform for two critical
 ## What can PaddleSpeech do?
 
 ### Speech-To-Text
-(An introduce of ASR in PaddleSpeech is needed here!)
+PaddleSpeech ASR mainly consists of components below:
+- Implementation of models and commonly used neural network layers.
+- Dataset abstraction and common data preprocessing pipelines.
+- Ready-to-run experiments.
+
+PaddleSpeech ASR provides you with a complete ASR pipeline, including:
+- Data Preparation
+    - Build vocabulary
+    - Compute Cepstral mean and variance normalization (CMVN)
+    - Featrue extraction
+        - Linear
+        - fbank (also support kaldi feature)
+        - mfcc
+- Acoustic Models
+    - Deepspeech2 (online and offline)
+    - Transformer (online and offline)
+    - Conformer (online and offline)
+- Decoder
+    - ctc greedy search (used in DeepSpeech2, Transformer and Conformer)
+    - ctc beam search (used in DeepSpeech2, Transformer and Conformer)
+    - attention decoding (used in Transformer and Conformer)
+    - attention rescoring (used in Transformer and Conformer)
 
+Speech-To-Text helps you training the ASR model very simply.
+   
 ### Text-To-Speech
 TTS mainly consists of components below:
 - Implementation of models and commonly used neural network layers.