Cannot open hevc mp4 file that was saved by ffmpeg itself

[chao]

Summary of the bug:
How to reproduce:

% ffprobe no_start_code_hevc.mp4
ffmpeg n5.1
built on Ubuntu 20.04.4 LTS

I used command

ffmpeg -i "rtsp://XXXX" -an -vcodec copy no_start_code_hevc.mp4

to save a footage file from a security camera. The result mp4 file is invalid. ffprobe returns

[extract_extradata @ 0x560de7b1bb80] No start code is found.
test.mp4: Invalid data found when processing input

[Carl Eugen Hoyos]

Replying to chao:

ffmpeg -i "rtsp://XXXX" -an -vcodec copy no_start_code_hevc.mp4

This is missing complete, uncut console output but there is no guarantee that this command line produces a valid output file.

[chao]

Replying to Carl Eugen Hoyos:
I assume you mean the RTSP URL is cut out?
It's from a GeoVision security camera that's not owned by me.
Let me see whether I can share the RTPS URL here.

[Carl Eugen Hoyos]

Valid tickets contain a command line together with the complete, uncut console output, in this case of the command that created the invalid file.

[chao]

Well, I don't get the permission to publish the RTSP URL here.
I was hoping the mp4 file would be useful..

[Carl Eugen Hoyos]

We don’t care about the url, we want to see the command line you tested together with the console output.

[Yu Liu]

I think i've met the same problem. use ffmpeg save rtsp(video codec is hevc) to mp4,and ffplay shows 'No start code is found'
tested with 7.1.1 and this issue has has been fixed,while 7.1 still has same problem
maybe this commit fixed this?
​https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/5813e5aa344b8c03c83bf62e729be0f447944ed1