"color" video source fails to handle "size=1x1"?

[MasterQuestionable]

͏    ffmpeg -y -nostdin -nostats -v debug -f lavfi -i "color=#ff0000:1x1[0]; color=#0000ff:1x1[1]; [0][1]vstack,split[0][1]; [0]vflip,[1]hstack" -vframes 1 -compression_level 10 -pred none "0.png"
͏    ffmpeg -y -nostdin -nostats -v debug -f lavfi -i "color=#ff0000:1x1,format=rgb24[0]; color=#0000ff:1x1,format=rgb24[1]; [0][1]vstack,split[0][1]; [0]vflip,[1]hstack" -vframes 1 -compression_level 10 -pred none "0.png" -vframes 1 -vf "format=yuvj420p" -sws_flags spline+accurate_rnd+full_chroma_int -lossless 1 -q 100 -compression_level 6 "1.webp"

͏    It appears "color" asserts "yuv420p" pixel format: which might be problematic (in particular for writing PNG alike).
͏    Semantic-wise, it's using RGB notation representing colors: while covertly collapsed to subsampled YUV...

͏    See also:
͏    https://ffmpeg.org/ffmpeg-filters.html#color
͏    https://ffmpeg.org/ffmpeg-filters.html#split_002c-asplit

[Marton Balint]

What is the expected behaviour, and what is the actual? What is the error message?

[MasterQuestionable]

͏    Run it things should be very apparent.

͏    See also:
͏    ​https://trac.ffmpeg.org/wiki/colorspace
͏    ​https://gist.github.com/Jim-Bar/3cbba684a71d1a9d468a6711a6eddbeb#420-422--and-subsampling

͏    Expected behavior (perhaps?):
͏    Similar colors represented using RGB probably shouldn't be asserted YUV (thus the covert conversion).

[Marton Balint]

Apparent how?

[MasterQuestionable]

͏    Run the 2 commands; also the "size=3x3" variant for the 1st.
͏    Notice keyword "yuv420".

͏    "1.webp" as pseudo-reference demonstrating the impact.

[Marton Balint]

Please follow https://ffmpeg.org/bugreports.html when reporting bugs, and provide the console output of your command lines.

[MasterQuestionable]

͏    I try to make things as succinct as possible.
͏    It appears this somehow failed your parsing.
͏    Would you help me debugging by feedback some your parsing details? Thanks.

͏    |1| Did you ever run the mentioned command?
͏    |2| Do you read things out-of-order? (maybe even asynchronous parallel)
͏    |2.1| Or strictly blocking FIFO (First-In First-Out)?
͏    |3| Did you read the linked See also?

[Marton Balint]

Fixed in 77fc047bd91eaef615a2c36b93ee23d7d27e7d25. Used pixel format is auto-negotiated, so you can force using rgb if you want. (e.g. color=s=1x1:c=red,format=rgba).

Oops, edited commit hash to point to proper commit.

[MasterQuestionable]

͏    So it appears you didn't ever run the command...

͏    "color=#ff0000:1x1,format=rgb24" alike already work before the change.
͏    As for this commit's implication... unsure. (silently corrupted to YUV 4:2:0?)