FFmpeg throws errors on certain moov atom positions using pipe input

[tjgreen]

Summary of the bug:
For certain moov atom positions, FFmpeg throws errors when input is stdin, regardless of async: prefix usage. For positions further downstream, there seems to be an issue.

How to reproduce:

% cat fail.mp4 | ffmpeg -probesize 8192 -loglevel error -i pipe:0 -f null -
ffmpeg version 7.0.2
built on 2024-08-03

Errors upon output:

[mov,mp4,m4a,3gp,3g2,mj2 @ 0x135604e80] stream 0, offset 0x30: partial file
    Last message repeated 1 times
[in#0/mov,mp4,m4a,3gp,3g2,mj2 @ 0x600002ba0000] Error during demuxing: Invalid data found when processing input
Cannot determine format of input 0:0 after EOF
[vf#0:0 @ 0x6000025a1a70] Task finished with error code: -1094995529 (Invalid data found when processing input)
[vf#0:0 @ 0x6000025a1a70] Terminating thread with return code -1094995529 (Invalid data found when processing input)
[vost#0:0/wrapped_avframe @ 0x13570e510] Could not open encoder before EOF
[vost#0:0/wrapped_avframe @ 0x13570e510] Task finished with error code: -22 (Invalid argument)
[vost#0:0/wrapped_avframe @ 0x13570e510] Terminating thread with return code -22 (Invalid argument)

I will attach two files that show the defect (fail.mp4) and that work without issue (succeed.mp4)

[tjgreen]

Part 1/5 (4.4MB total)

[tjgreen]

Part 2/5 (4.4MB total)

[tjgreen]

Part 3/5 (4.4MB total)

[tjgreen]

Part 4/5 (4.4MB total)

[tjgreen]

Part 5/5 (4.4MB total)

[MasterQuestionable]

͏    The implication of Pipe is First-In First-Out (FIFO).
͏    Which means the data cannot be back-seeked (or access out of order):
͏    That may not always fulfill the ordinary parsing expectation.

[tjgreen]

Is this something that can be addressed, perhaps using caching?

[MasterQuestionable]

͏    Maybe. But there are performance concerns:
͏    That may not make this ideal as the unconditional default.

͏    Alike caching seems easily doable from the user's end.
͏    Probably not worth bothering the complexity of adding new option to config.