ENUM V4L2_JPEG_APP14_TF(9)

💖 enum v4l2_jpeg_app14_tf — the APP14 transform flag, bestie edition 💖

okay so this is a page from the Kernel API Manual, and it's literally all about one tiny enum that tells you what the APP14 segment is saying about colour encoding. grab a snack, we're decoding. 🍓

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✨ NAME ✨

enum v4l2_jpeg_app14_tf — the APP14 transform flag. Per Rec. ITU-T T.872 (06/2012) 6.5.3, the APP14 segment exists for colour encoding, and it holds a transform flag. That flag can have the values 0, 1 and 2, and they get interpreted as follows: 👇

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🌸 SYNOPSIS 🌸

enum v4l2_jpeg_app14_tf {
    V4L2_JPEG_APP14_TF_CMYK_RGB ,
    V4L2_JPEG_APP14_TF_YCBCR ,
    V4L2_JPEG_APP14_TF_YCCK ,
    V4L2_JPEG_APP14_TF_UNKNOWN

};

like, that's the whole enum, no cap. four constants, that's it, that's the vibe. 🎀

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🦋 Constants 🦋

💅 the four icons themselves

• V4L2_JPEG_APP14_TF_CMYK_RGB — CMYK for images encoded with four components, and RGB for images encoded with three components. yes, it's one constant doing double duty, she contains multitudes. 👑
• V4L2_JPEG_APP14_TF_YCBCR — an image encoded with three components using YCbCr. three components, YCbCr, slay. ✨
• V4L2_JPEG_APP14_TF_YCCK — an image encoded with four components using YCCK. four components this time, okurrr. 🫶
• V4L2_JPEG_APP14_TF_UNKNOWN — indicates app14 is not present. the "no thoughts, head empty" option, literally. 💀

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🔥 SEE ALSO 🔥

kernel file ./include/media/v4l2-jpeg.h, plus the whole friend group:

• struct v4l2_jpeg_reference(9)
• struct v4l2_jpeg_frame_component_spec(9)
• struct v4l2_jpeg_frame_header(9)
• struct v4l2_jpeg_scan_component_spec(9)
• struct v4l2_jpeg_scan_header(9)
• struct v4l2_jpeg_header(9)

go read them, iykyk. 📚💜

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ngl, if you're poking at JPEG headers in the kernel, this enum is your main character energy. memorize the four constants and you're golden. 🌈⭐

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and that's a wrap, bestie! this lil gem lives in ./include/media, and the page is dated October 2026 (yes, the future, we're just that ahead 💅). bye, ily, go read your headers! 🦋✨🎀💖