ffmpeg doesn't see the audio stream that definitely exists

[bitworld58]

Summary of the bug:
Stream map '0:a' matches no streams.
To ignore this, add a trailing '?' to the map.
Failed to set value '0:a' for option 'map': Invalid argument
Error parsing options for output file output.mp3.
Error opening output files: Invalid argument

ffmpeg version N-115067-gdf868bae23-20240504

How to reproduce:

ffmpeg -i test.h265 -map 0:a -c:a copy output.mp3

[mkver]

It is intended and not a bug that remapping non-existing streams errors out.

[bitworld58]

It turns out that the format is not supported? Audio is available in players

[mkver]

If you claim that this file is in reality mp3 and gets misdetected (if the mp3 demuxer is forced, it instead errors out with "Failed to read frame size: Could not seek to 7530."), you need to say so. You also need to say what other player can play this file.

[bitworld58]

File from an IP camera with video and sound, video can be extracted, but audio is not detected
This player plays with sound: ​https://www.polyvision.ru/upload/programs/sw/Player07112022_setup.exe
This program converts to mp4 with sound: ​http://www.youcam.pro/soft/VideoConver.zip
Also, any VMS plays with sound

[MasterQuestionable]

͏    The format appears atypical.
͏    My guess is that of sort of raw concatenation: which couldn't be possibly perfectly supported by FFmpeg.
͏    (given the ͏"test.h265" indeed contains the claimed audio stream)