That is a typical problem with captures from TV.
When MediaInfo/eac3to read the first header of AC3 show:
Format : AC-3
Duration : 56 min 46 s
Bit rate : 384 kb/s
Channel(s) : 2 channels
Stream size : 156 MiB
All seems correct and we can expect a decoded wav (64 bits) size of:
3406 sec. x 2 ch. x 8 bytes/ch x 48000 samples/sec = 2495 MB
But the decoded wav is:
Caution: The WAV file is bigger than 4GB.
because only the first's AC3 are 2.0 and the rest are 5.1, then the decoded wav have 3 times (6ch/2ch) size and are buggy (noise) recoded to a m4a with a duration of:
3406 sec x 3 = 2h 50m
near the duration 2 h 48 min of m4a (seems there are a few of AC3 2.0 frames, maybe commercials)
An AC3 with a mix of 2.0 and 5.1 frames are invalid and can't be recoded properly, you need obtain valid AC3 from it.
You can use DelayCut or a tool I wrote:
SplitAc3
Other related threads:
https://forum.doom9.org/showthread.p...27#post1679327
https://forum.doom9.org/showthread.p...31#post1768231