--- a
+++ b/tools/data/anno_txt2json.py
@@ -0,0 +1,103 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+import argparse
+
+import mmcv
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(
+        description='Convert txt annotation list to json')
+    parser.add_argument(
+        'annofile', type=str, help='the txt annotation file to convert')
+    parser.add_argument(
+        '--format',
+        type=str,
+        default='rawframes',
+        choices=['rawframes', 'videos'],
+        help='the format of the txt annotation file')
+    parser.add_argument(
+        '--output',
+        type=str,
+        default=None,
+        help=(
+            'the output file name, use annofile.replace(\'.txt\', \'.json\') '
+            'if the arg value is None'))
+    args = parser.parse_args()
+
+    return args
+
+
+def lines2dictlist(lines, format):
+    """Convert lines in 'txt' format to dictionaries in 'json' format.
+    Currently support single-label and multi-label.
+
+    Example of a single-label rawframes annotation txt file:
+
+    .. code-block:: txt
+
+        (frame_dir num_frames label)
+        some/directory-1 163 1
+        some/directory-2 122 1
+        some/directory-3 258 2
+
+    Example of a multi-label rawframes annotation txt file:
+
+    .. code-block:: txt
+
+        (frame_dir num_frames label1 label2 ...)
+        some/directory-1 163 1 3 5
+        some/directory-2 122 1 2
+        some/directory-3 258 2
+
+    Example of a single-label videos annotation txt file:
+
+    .. code-block:: txt
+
+        (filename label)
+        some/path/000.mp4 1
+        some/path/001.mp4 1
+        some/path/002.mp4 2
+
+    Example of a multi-label videos annotation txt file:
+
+    .. code-block:: txt
+
+        (filename label1 label2 ...)
+        some/path/000.mp4 1 3 5
+        some/path/001.mp4 1 4 8
+        some/path/002.mp4 2 4 9
+
+    Args:
+        lines (list): List of lines in 'txt' label format.
+        format (str): Data format, choices are 'rawframes' and 'videos'.
+
+    Returns:
+        list[dict]: For rawframes format, each dict has keys: frame_dir,
+            total_frames, label; for videos format, each diction has keys:
+            filename, label.
+    """
+    lines = [x.split() for x in lines]
+    if format == 'rawframes':
+        data = [
+            dict(
+                frame_dir=line[0],
+                total_frames=int(line[1]),
+                label=[int(x) for x in line[2:]]) for line in lines
+        ]
+    elif format == 'videos':
+        data = [
+            dict(filename=line[0], label=[int(x) for x in line[1:]])
+            for line in lines
+        ]
+    return data
+
+
+if __name__ == '__main__':
+    # convert txt anno list to json
+    args = parse_args()
+    lines = open(args.annofile).readlines()
+    lines = [x.strip() for x in lines]
+    result = lines2dictlist(lines, args.format)
+    if args.output is None:
+        args.output = args.annofile.replace('.txt', '.json')
+    mmcv.dump(result, args.output)