The metadata was packed in nal-units with nal_type=31, fixed with 907fbb59435b96e5c77a90894f1206ec1058f8d7.

[drinkthatcodingZzZz]

The metadata was packed in nal-units with nal_type=31, fixed with 907fbb5.

Additionally ffmpeg3.4+ failed to decode some mp4a samples, because internal decoder state was not reset after 'gaps' in the audio-stream. These gaps may be caused by network transmission errors. This got fixed with 56aee28.

Tip
When using ffmpeg you can avoid corrupt files by using -f mpegts.
This will create .ts instead of .mp4.
It also allows you to watch the stream while downloading.
Later you can use ffmpeg -i file.ts -c copy file.mp4.

Originally posted by @anthwlock in #51 (comment)

[drinkthatcodingZzZz]

how do i apply these fixes to my files? @anthwlock

[anthwlock]

These fixes refer to the untrunc program itself. You have to use untrunc as described here