On 12/2/2025 12:36 AM, Michael Niedermayer via ffmpeg-devel wrote:
Hi Gavin

this patch breaks decoding a video with a single image:

this works and creates our single image video
./ffmpeg -i lena.pnm /tmp/file.m2v

this fails after the patch:
./ffmpeg -i /tmp/file.m2v /tmp/file.jpg -y

[image2 @ 0x60dca024f140] Cannot write more than one file with the same name. 
Are you missing the -update option or a sequence pattern?
[vost#0:0/mjpeg @ 0x60dca024f3c0] Error submitting a packet to the muxer: 
Invalid argument
     Last message repeated 1 times
[out#0/image2 @ 0x60dca024f040] Error muxing a packet
[out#0/image2 @ 0x60dca024f040] Task finished with error code: -22 (Invalid 
argument)
[out#0/image2 @ 0x60dca024f040] Terminating thread with return code -22 
(Invalid argument)
[out#0/image2 @ 0x60dca024f040] video:375KiB audio:0KiB subtitle:0KiB other 
streams:0KiB global headers:0KiB muxing overhead: unknown
frame=    2 fps=0.0 q=5.0 Lsize=N/A time=00:00:00.04 bitrate=N/A dup=1 drop=0 
speed=0.455x elapsed=0:00:00.08
Conversion failed!

This also breaks:
./ffmpeg -i https://trac.ffmpeg.org/raw-attachment/ticket/3923/frame16.h264 
test.jpg

rawdec has a user parameter called framerate which is set to 25 by default.
If your input is not 25, obviously then it should not be set to 25.

Your change does not achive a fallback of 25 if it cannot be determined,
as clearly shown in the example above where our single frame is turned into
2 frames, clearly showing there is a new inconsistancy.

I suggest to revert this patch (to avoid creating more bugs by a rushed attempt 
to
fix this) and attempt to fix your file by setting the user framerate parameter 
correctly

Independant of this, making it autodetect would be cool, yes, i agree
but i think we need more time, testing and no regressions

As the committer, I'm ok reverting it if it introduces regressions, but we should work towards having this fixed considering many of the fate changes were correct.

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