求教，网页drm解码得到音频

最近对onleihe.de网络有声读物感兴趣，想下载下来听，琢磨如何破解网络drm解码，从而得到音频的真实地址。
试过用chrome的network找地址，亦或m3u3的playlist。network file list 如下

default_settings.css	
bundle.js
data:application/fo…	
background-body.jpg	
mediatype_book.gif	
drm?token=eyJhbGciOiJIUzUxMiJ9.eyJpc3MiOiJodHRwOi8…UBqceKLI-zvcWNK0HMnKbpsg77eIKMhIPOqM5AD_iXgfQ8pIAmetadata?token=eyJhbGciOiJIUzUxMiJ9.eyJpc3MiOiJodH…UBqceKLI-zvcWNK0HMnKbpsg77eIKMhIPOqM5AD_iXgfQ8pIA
translations	
1?token=eyJhbGciOiJIUzUxMiJ9.eyJpc3MiOiJodHRwOi8vZ…UBqceKLI-zvcWNK0HMnKbpsg77eIKMhIPOqM5AD_iXgfQ8pIA	
im978-3-89813-937-3s.jpg	
Manifest.mpd	
978-3-89813-937-3.wma.mp4	
978-3-89813-937-3.wma.mp4	
978-3-89813-937-3.wma.mp4	
978-3-89813-937-3.wma.mp4	
Preflight?assetId=20415171-ccb5-51f6-459f-965c7b6b2aa3&variantId=1	
978-3-89813-937-3.wma.mp4	
978-3-89813-937-3.wma.mp4	
?assetId=20415171-ccb5-51f6-459f-965c7b6b2aa3&variantId=1	
register/
其中的mp4链接是 https://streaming.onleihe.de/castlabs_s04/2016-06-03/20415171-ccb5-51f6-459f-965c7b6b2aa3/978-3-89813-937-3.wma.mp4  但下载来的音频播放出错。
现在没有头绪，为了避免走弯路，特此请教各位大神，
1. 如何找出方法下载正确的音频链接，或解码可以正确播放音频。
2. 音频的编码是否可以通过assetId中的function（如下）转换，从而可以正常播放
{name: "widevine_cdm_version", value: "4.10.2391.0"}name: "widevine_cdm_version"value: "4.10.2391.0"client_max_hdcp_version: "HDCP_V1"content_owner: "castlabs"content_provider: "castlabs"device_state: "RELEASED"device_whitelist_state: "DEVICE_NOT_WHITELISTED"drm_cert_serial_number: "NDY4NWI0OTk3YjI3MmNjNmFkNDUyMGZjYmZiMDNjMGE="internal_status: 0license: "CAISmgIKNAoQV7p2buQUV1qZyYm/TKyAfhIQV7p2buQUV1qZyYm/TKyAfhoAIAEoADgAQABIwdXajwYSDAgBEAAYACAAKABgARpmEhAup/fvlNh5UkY+nQHpG9sbGlBzeP1xTcrVVVZeuVg3WWElBZhOMJUu+D2yvqDStZDvLev5M70Qvytrr73WaK5PNUG0Q8Vzpx+UXZ6NJClrK1yrO3FU7QglpM3pK3odH09k6yABGmIKEN9SQ7zrVUUes8LlkkPXtCkSEDD8/OXmqf8EQOGY0+oW8PsaIIVgp+NOw71PMcTgWeXDTBa8Iiy0uWajTOF0zsTciGtCIAIoAUISChBrYzE2AAAAAPVyCo2AAAAIYgJIRCDB1dqPBjgAUAUaIF05FhAul2vDcqu5G7yCkpy2umNDT3whMdtcHL0FaE1IIoABh8+KYJV2Ch1QPgEZ49zSSbJYg/jnBWTyweplhS38l8bupYvtflNLDw+kyUw8Le/NxL4R2upCwBfGF7TjQYhuVCc4J03esEkRazVkOuq1pdkA0BuiIe1v00le83JhVE9Ll8njVWCKciW+9ohSLvTY2JqSAg4xhVzV85Fd8kDJp706MwoxMTYuNS4wIEJ1aWx0IG9uIERlYyAxNSAyMDIxIDEwOjI3OjE3ICgxNjM5NTkyODE1KUABSrABAAAAAgAAALAABQAQ9XIKjTg0UGsAAABIAAAAEAAAAFoAAABQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAACwAAAAEAAAAMIAAAAQAAAA1AAAABAAAAAAAAAAAAAAAPwAAAAQf20OcSLWJOR2RZuUhbzkZbVHLOAO7BHtlNMDZ9wK/f5YAQ=="license_metadata: {content_id: "31JDvOtVRR6zwuWSQ9e0KQ==", license_type: "STREAMING", request_type: "NEW"}content_id: "31JDvOtVRR6zwuWSQ9e0KQ=="license_type: "STREAMING"request_type: "NEW"make: "Google"message_type: "LICENSE"model: "ChromeCDM-Win-x64-7"oem_crypto_api_version: 16platform: "windows"platform_verification_status: "PLATFORM_SECURE_STORAGE_SOFTWARE_VERIFIED"
3. 能否推荐专业书籍帮助一步一步学习上述解码技术。 谢谢。