[Feature Request] jxl format

[myshzzx]

jxl is better than avif/webp on coding efficiency and running speed
ffmpeg has jxl animation codec, and browsers are bringing their support back.

[fz0000]

I have reviewed the code of ScreenToGif and the help doc of ffmpeg.exe, maybe it's not that easy after all..

For the default ffmpeg.exe, ScreenToGif uses the first package in the assets of the latest release.
It's an essentials build and does not fully support JXL format: it supports demuxing but does not contain the decoder, or in plain words, it can recognize the JXL file format, but cannot read the content.

Unfortunately, even with the full build, FFmpeg only supports importing animated JXL, not exporting it.
While the full build has the encoder (via libjxl), it lacks the corresponding muxer for animated JXL. As a result, FFmpeg falls back to the image2 sequence muxer, which saves each frame as a separate static JXL file — not a single animated JXL.

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说人话就是：静态jxl文件或许还能想想办法，动画的话，臣妾做不到啊 🥲