Format total_audio_files_length_sec similar to duration

Current format:
    "total_audio_files_length_sec": **2948**,
    "duration": "0:10:36",
Change to:
    "total_audio_files_length_sec": **"0:49:13"**,
    "duration": "0:10:36",

2948 seconds is 49 minutes and 13 seconds