Add flag to use chapters offset for non audible files tagged using audible api

README.md

@@ -114,6 +114,7 @@ optional arguments:
                         Output directory
   -p PATH_FORMAT, --path_format PATH_FORMAT
                         Structure of output path/naming.Supported terms: author, narrator, series_name, series_position, subtitle, title, year
+  --chapters-offset     For files not from Audible, adjust chapters to offset according to brandIntroDurationMs
 
 ```
 

src/m4b_merge/__main__.py

@@ -26,7 +26,7 @@ def run_all(input_path):
     # Create BookData object from asin response
     aud = audible_helper.BookData(asin)
     metadata = aud.fetch_api_data(config.api_url)
-    chapters = aud.get_chapters()
+    chapters = aud.get_chapters(config.use_chapters_offset)
 
     # Process metadata and run components to merge files
     m4b = m4b_helper.M4bMerge(input_data, metadata, input_path, chapters)
@@ -39,6 +39,11 @@ def validate_args(args):
         config.api_url = args.api_url
     else:
         config.api_url = "https://api.audnex.us"
+    # Chapter offset for non audible files
+    if args.chapters_offset:
+        config.use_chapters_offset = True
+    else:
+        config.use_chapters_offset = False
     # Completed Directory
     if args.completed_directory:
         config.junk_dir = args.completed_directory
@@ -84,6 +89,7 @@ def validate_args(args):
     logging.debug(f'Using CPU cores: {config.num_cpus}')
     logging.debug(f'Using output path: {config.output}')
     logging.debug(f'Using output format: {config.path_format}')
+    logging.debug(f'Using chapters offset: {config.use_chapters_offset}')
     # Inputs
     # Last to be checked
     if args.inputs:
@@ -143,6 +149,12 @@ def main():
         ),
         type=str
     )
+    parser.add_argument(
+        "--chapters-offset",
+        help="For files not from Audible, adjust chapters to offset according to brandIntroDurationMs",
+        action="store_true",
+        required=False
+    )
 
     validate_args(parser.parse_args())
 

src/m4b_merge/audible_helper.py

@@ -37,10 +37,13 @@ def ms_to_timestamp(self, input_duration):
 
         return timestamp + '.' + '000'
 
-    def get_chapters(self):
+    def get_chapters(self, use_chapters_offset):
         # Select chapter data from json response
         chapter_info = self.metadata_dict['chapter_info']
-
+        if use_chapters_offset:
+            offset = chapter_info.get('brandIntroDurationMs', 0)
+        else:
+            offset = 0    
         # Only use Audible chapters if tagged as accurate
         if 'isAccurate' in chapter_info and chapter_info['isAccurate'] is True:
             chapter_output = []
@@ -54,8 +57,11 @@ def get_chapters(self):
             )
 
             # Append each chapter to array
-            for chapter in chapter_info['chapters']:
-                chap_start = self.ms_to_timestamp(chapter['startOffsetMs'])
+            for index, chapter in enumerate(chapter_info['chapters']):
+                if index == 0:
+                    chap_start = self.ms_to_timestamp(chapter['startOffsetMs'])
+                else:
+                    chap_start = self.ms_to_timestamp(chapter['startOffsetMs'] - offset)
                 # Starting chapter title data
                 chapter_title = chapter['title']
                 chapter_output.append(