if first chapter starts at non-zero time, youtube-dl (or maybe ffmpeg?) ignores it and you end up with the first chapter starting at the wrong time. So, when first chapter does not start at time 0, insert an "Intro" chapter, so that the music starts at a chapter marker.

youtube_dl/extractor/digitalconcerthall.py

@@ -96,8 +96,18 @@ class DigitalConcertHallIE(InfoExtractor):
                 entries[-1]['description'] = vid_info.get('short_description', "missing description")
             if vid_info.get('cuepoints'):
                 chapters = []
+                first_chapter = 1
                 for chapter in vid_info.get('cuepoints'):
                     start_time = chapter.get('time')
+                    # Often, the first chapter does not start at zero.  In this case,
+                    # insert an intro chapter so that first chapter is the start of the music
+                    if (first_chapter == 1) and (start_time != 0):
+                        chapters.append({
+                            'start_time': 0,
+                            'end_time': start_time,
+                            'title': '0. Intro'
+                        })
+                    first_chapter = 0
                     end_time = start_time + chapter.get('duration')
                     chapter_title = chapter.get('text')
                     chapters.append({