Change default value of lattice-score-scale from 1.0 to 0.5 (#41)

* Change the default value of lattice-score-scale from 1.0 to 0.5

* Fix CI.

.github/workflows/test.yml

@@ -53,6 +53,20 @@ jobs:
           # icefall requirements
           pip install -r requirements.txt
 
+      - name: Install graphviz
+        if: startsWith(matrix.os, 'ubuntu')
+        shell: bash
+        run: |
+          python3 -m pip install -qq graphviz
+          sudo apt-get -qq install graphviz
+
+      - name: Install graphviz
+        if: startsWith(matrix.os, 'macos')
+        shell: bash
+        run: |
+          python3 -m pip install -qq graphviz
+          brew install -q graphviz
+
       - name: Run tests
         if: startsWith(matrix.os, 'ubuntu')
         run: |

egs/librispeech/ASR/conformer_ctc/decode.py

@@ -108,7 +108,7 @@ def get_parser():
     parser.add_argument(
         "--lattice-score-scale",
         type=float,
-        default=1.0,
+        default=0.5,
         help="""The scale to be applied to `lattice.scores`.
         It's needed if you use any kinds of n-best based rescoring.
         Used only when "method" is one of the following values:
@@ -278,7 +278,8 @@ def decode_one_batch(
         "attention-decoder",
     ]
 
-    lm_scale_list = [0.8, 0.9, 1.0, 1.1, 1.2, 1.3]
+    lm_scale_list = [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7]
+    lm_scale_list += [0.8, 0.9, 1.0, 1.1, 1.2, 1.3]
     lm_scale_list += [1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0]
 
     if params.method == "nbest-rescoring":

egs/librispeech/ASR/tdnn_lstm_ctc/decode.py

@@ -206,7 +206,8 @@ def decode_one_batch(
 
     assert params.method in ["nbest-rescoring", "whole-lattice-rescoring"]
 
-    lm_scale_list = [0.8, 0.9, 1.0, 1.1, 1.2, 1.3]
+    lm_scale_list = [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7]
+    lm_scale_list += [0.8, 0.9, 1.0, 1.1, 1.2, 1.3]
     lm_scale_list += [1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0]
 
     if params.method == "nbest-rescoring":