Scale followed by vstack stopped working

[Marth64]

Summary of the bug:
Since e61b9d4094d76f5fede0b65139d17add281e6e45 fftools/ffmpeg: propagate decoded_side_data from decoded streams to the filterchain

How to reproduce:

ffmpeg -i tst.png -i tst.png -filter_complex "[0:v:0]scale=720:480[front];[1:v:0]scale=720:480[back];[front][back]vstack=2" -f null -

Result

ffmpeg version N-118362-ge61b9d4094 Copyright (c) 2000-2025 the FFmpeg developers
  built with Apple clang version 16.0.0 (clang-1600.0.26.6)
  configuration: --enable-debug=3 --enable-nonfree --enable-gpl --enable-demuxer=dvdvideo --enable-libdvdread --enable-libdvdnav --samples=fate-suite/
  libavutil      59. 55.100 / 59. 55.100
  libavcodec     61. 31.101 / 61. 31.101
  libavformat    61.  9.106 / 61.  9.106
  libavdevice    61.  4.100 / 61.  4.100
  libavfilter    10.  9.100 / 10.  9.100
  libswscale      8. 13.100 /  8. 13.100
  libswresample   5.  4.100 /  5.  4.100
  libpostproc    58.  4.100 / 58.  4.100
Input #0, png_pipe, from 'tst.png':
  Duration: N/A, bitrate: N/A
  Stream #0:0: Video: png, rgba(pc, gbr/unknown/unknown), 720x480 [SAR 971:894 DAR 971:596], 25 fps, 25 tbr, 25 tbn
Input #1, png_pipe, from 'tst.png':
  Duration: N/A, bitrate: N/A
  Stream #1:0: Video: png, rgba(pc, gbr/unknown/unknown), 720x480 [SAR 971:894 DAR 971:596], 25 fps, 25 tbr, 25 tbn
Stream mapping:
  Stream #0:0 (png) -> scale:default
  Stream #1:0 (png) -> scale:default
  vstack:default -> Stream #0:0 (wrapped_avframe)
Press [q] to stop, [?] for help
[Parsed_vstack_2 @ 0x600002628180] Input 1 width 0 does not match input 0 width 720.
[Parsed_vstack_2 @ 0x600002628180] Failed to configure output pad on Parsed_vstack_2
[fc#0 @ 0x600002228000] Error reinitializing filters!
[fc#0 @ 0x600002228000] Task finished with error code: -22 (Invalid argument)
[fc#0 @ 0x600002228000] Terminating thread with return code -22 (Invalid argument)
[vost#0:0/wrapped_avframe @ 0x15b7086f0] [enc:wrapped_avframe @ 0x6000038285b0] Could not open encoder before EOF
[vost#0:0/wrapped_avframe @ 0x15b7086f0] Task finished with error code: -22 (Invalid argument)
[vost#0:0/wrapped_avframe @ 0x15b7086f0] Terminating thread with return code -22 (Invalid argument)
[out#0/null @ 0x600002624240] Nothing was written into output file, because at least one of its streams received no packets.
frame=    0 fps=0.0 q=0.0 Lsize=       0KiB time=N/A bitrate=N/A speed=N/A    
Conversion failed!

Patches should be submitted to the ffmpeg-devel mailing list and not this bug tracker.

[Gyan]

Can't reproduce here. Is this input-specific?

[Marth64]

sample

[Marth64]

Hi, appears to always be impacting PNG files screenshots taken from macOS (but hit or miss with other PNG sources).

Attached a sample.

[Marth64]

second sample

[James]

Regression since ef1cb1c9c810b30c5c9356c07eef07dc8edc3aea

[James]

Should be fixed in db7ff135744d171bfc6adc7d4af065f9d853233f