add new instructions on how to get manifest *.tsv file (#5207)

Co-authored-by: Andros Tjandra <androstj@fb.com>

examples/mms/README.md

@@ -72,10 +72,12 @@ dev.ltr
 dev.uid
 
 # dev.tsv each line contains <audio>  <number_of_sample>
+# if user don't have this information, please run misc/get_sample_size.py
+
 $ cat dev.tsv
 /
-/path/to/audio_1  180000
-/path/to/audio_2  200000
+/path/to/audio_1.wav  180000
+/path/to/audio_2.wav  200000
 
 $ cat dev.ltr
 t h i s | i s | o n e |

examples/mms/misc/get_sample_size.py

@@ -0,0 +1,29 @@
+#!/usr/bin/env python -u
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+"""
+Usage:
+    $ python misc/get_sample_size.py <input_file> > <output_file>
+    
+    <input_file> contains list of wav files
+    $ cat <input_file>
+      /path/to/audio_1.wav
+      /path/to/audio_2.wav
+
+    <output_file> contains list of wav files paired with their number of samples
+    $ cat <output_file>
+      /path/to/audio_1.wav    180000
+      /path/to/audio_2.wav    120000
+"""
+import sys
+import soundfile as sf
+
+if __name__ == "__main__":
+    files = sys.argv[1]
+    with open(files) as fr:
+        for fi in fr:
+            fi = fi.strip()
+            print(f'{fi}\t{sf.SoundFile(fi).frames}')