FFmpeg piping result in error

[Khaoklong51]

When pipe wav stream from ffmpeg to flac. The encode is not complete.

flac 1.5.0
Copyright (C) 2000-2009  Josh Coalson, 2011-2025  Xiph.Org Foundation
flac comes with ABSOLUTELY NO WARRANTY.  This is free software, and you are
welcome to redistribute it under certain conditions.  Type `flac' for details.

-: WARNING: skipping unknown chunk 'LIST' (use --keep-foreign-metadata to keep)
-: 5% complete, ratio=0.309-: WARNING: unexpected EOF; expected 1073741823 samples, got 65376256 samples
6% complete, ratio=0.308

I don't know if this is ffmpeg bug or flac bug itself but opusenc does not have this problem.

link from someone has the same issue:
https://stackoverflow.com/questions/56138370/problems-piping-ffmpeg-to-flac-encoder

Command Used:

ffmpeg -i "input.mkv" -f wav - | flac -o output.flac

[ktmf01]

When pipe wav stream from ffmpeg to flac. The encode is not complete.

How much is missing?

link from someone has the same issue: https://stackoverflow.com/questions/56138370/problems-piping-ffmpeg-to-flac-encoder

Have you read it? Seems the answer is quite comprehensive and explains why this happens.