Blog post: http://forensenellanebbia.blogspot.it/2015/12/wechat-script-to-convert-and-play-aud.html

Prerequisites:

• Python v2.7
• libav for Microsoft Windows (Open source audio and video processing tools - https://www.libav.org/) Tested version: http://builds.libav.org/windows/nightly-gpl/libav-x86_64-w64-mingw32-20151130.7z
• Silk v3 decoder (decoder.exe from https://github.com/netcharm/wechatvoice)
• FFMpeg (https://ffmpeg.org/download.html)

What you have to do first:

• export WeChat chats in HTML format using the UFED Physical Analyzer software ("Export to HTML" option)
• put libav, decoder.exe and ffmpeg in c:\tools

What the script does:

• this script converts WeChat audio messages to WAV files
• it then modifies each HTML report by replacing the strings ".aud" and ".amr" with ".wav"

Script based on these blog posts/scripts:

• https://ppwwyyxx.com/blog/2014/Classify-WeChat-Audio-Messages/
• https://www.giacomovacca.com/2013/06/voip-calls-encoded-with-silk-from-rtp.html
• https://github.com/netcharm/wechatvoice (https://github.com/netcharm/wechatvoice/blob/master/amr2ogg.py)