STRUCT V4L2_JPEG_HEADER(9)

🎀 struct v4l2_jpeg_header(9) 🎀

okay so this is the <pink>struct v4l2_jpeg_header</pink> manpage from the Kernel API Manual — and yes bestie, the whole thing is literally about one struct: parsed JPEG header. that's it. that's the vibe. 💅

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✨ NAME ✨

struct v4l2_jpeg_header — parsed JPEG header 🖼️✨

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🌸 SYNOPSIS 🌸

struct v4l2_jpeg_header {
    struct v4l2_jpeg_reference sof;
    struct v4l2_jpeg_reference sos;
    unsigned int num_dht;
    struct v4l2_jpeg_reference dht[V4L2_JPEG_MAX_TABLES];
    unsigned int num_dqt;
    struct v4l2_jpeg_reference dqt[V4L2_JPEG_MAX_TABLES];
    struct v4l2_jpeg_frame_header frame;
    struct v4l2_jpeg_scan_header *scan;
    struct v4l2_jpeg_reference *quantization_tables;
    struct v4l2_jpeg_reference *huffman_tables;
    u16 restart_interval;
    size_t ecs_offset;
    enum v4l2_jpeg_app14_tf app14_tf;
 };

like, look at her. she's got range. 👑

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🦋 Members 🦋

okay bestie, field-by-field, no skips, periodt:

• sof — pointer to frame header and size 🫶
• sos — pointer to scan header and size 💖
• num_dht — number of entries in dht 🌸
• dht — pointers to huffman tables and sizes ✨
• num_dqt — number of entries in dqt 🎀
• dqt — pointers to quantization tables and sizes 💜
• frame — parsed frame header 👑
• scan — pointer to parsed scan header, optional ⭐
• quantization_tables — references to four quantization tables, optional 🌈
• huffman_tables — references to four Huffman tables in DC0, DC1, AC0, AC1 order, optional 🧚
• restart_interval — number of MCU per restart interval, Ri 🔁
• ecs_offset — buffer offset in bytes to the entropy coded segment 📍
• app14_tf — transform flag from app14 data 🏳️

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💀 Description 💀

so here's the tea ☕: when this struct gets passed to v4l2_jpeg_parse_header, those optional pointers — scan, quantization_tables, and huffman_tables — must be initialized to NULL or point at valid memory. like, no cap, that's not optional-optional, that's a real requirement. 🙈

bestie pls don't hand over a random uninitialized pointer here, that's giving undefined behavior energy and we are not about that life 😭

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🔥 SEE ALSO 🔥

• Kernel file ./include/media/v4l2-jpeg.h — go read the source, iykyk 📖
• 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)
• enum v4l2_jpeg_app14_tf(9)

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and that's the whole page, bestie 🫶✨ this one lives in ./include/media, dated October 2026, and it's brought to you by the Kernel API Manual — slay, ate, no crumbs. 💅🎀🦋