STRUCT V4L2_VP9_LOOP_FILTER(9)

💅 struct v4l2_vp9_loop_filter(9) — like, the Kernel API Manual bestie ✨

okay so bestie, gather round, because we're about to get into struct v4l2_vp9_loop_filter and honestly? it's giving "small struct, big responsibilities" 🎀 this is the VP9 loop filter parameters situation and you're gonna understand it fr fr.

---

🌸 NAME 🌸

struct v4l2_vp9_loop_filter — VP9 loop filter parameters 💖

---

✨ SYNOPSIS ✨

like, here's the whole vibe, character for character, no cap:

struct v4l2_vp9_loop_filter {
    __s8 ref_deltas[4];
    __s8 mode_deltas[2];
    __u8 level;
    __u8 sharpness;
    __u8 flags;
    __u8 reserved[7];
 };

---

🦋 Members 🦋

• ref_deltas — this one holds the adjustment you need for the filter level, based on whichever reference frame got chosen 👑 and listen: if this syntax element is not present in the bitstream, users should pass its last value. that's the rule, periodt.
• mode_deltas — same energy, but for the chosen mode 💫 it's the adjustment needed for the filter level based on the mode. and yup, if this syntax element isn't present in the bitstream, users should pass its last value too. iykyk.
• level — indicates the loop filter strength 🔥
• sharpness — indicates the sharpness level ⭐
• flags — a combination of V4L2_VP9_LOOP_FILTER_FLAG_{} flags 🌈
• reserved — padding field 🫶 and it should be zeroed by applications. not me reminding you twice, but like, zero it. 🙈

---

💜 Description 💜

This structure contains all loop filter related parameters. See sections 📖

ngl the original just trails off right there with "See sections" and honestly? iconic cliffhanger behaviour 💀 we're keeping it exactly as it is, no invented lore.

---

🧚 SEE ALSO 🧚

Kernel file ./include/uapi/linux/v4l2-controls.h — and now the whole friend group, in order, because every single one of them is invited to the function 💅:

• enum v4l2_mpeg_video_av1_profile(9)
• enum v4l2_mpeg_video_av1_level(9)
• enum v4l2_stateless_h264_decode_mode(9)
• enum v4l2_stateless_h264_start_code(9)
• struct v4l2_ctrl_h264_sps(9)
• struct v4l2_ctrl_h264_pps(9)
• struct v4l2_ctrl_h264_scaling_matrix(9)
• struct v4l2_ctrl_h264_pred_weights(9)
• struct v4l2_h264_reference(9)
• struct v4l2_ctrl_h264_slice_params(9)
• struct v4l2_h264_dpb_entry(9)
• struct v4l2_ctrl_h264_decode_params(9)
• struct v4l2_ctrl_fwht_params(9)
• struct v4l2_vp8_segment(9)
• struct v4l2_vp8_loop_filter(9)
• struct v4l2_vp8_quantization(9)
• struct v4l2_vp8_entropy(9)
• struct v4l2_vp8_entropy_coder_state(9)
• struct v4l2_ctrl_vp8_frame(9)
• struct v4l2_ctrl_mpeg2_sequence(9)
• struct v4l2_ctrl_mpeg2_picture(9)
• struct v4l2_ctrl_mpeg2_quantisation(9)
• struct v4l2_ctrl_hevc_sps(9)
• struct v4l2_ctrl_hevc_pps(9)
• struct v4l2_hevc_dpb_entry(9)
• struct v4l2_hevc_pred_weight_table(9)
• struct v4l2_ctrl_hevc_slice_params(9)
• struct v4l2_ctrl_hevc_decode_params(9)
• struct v4l2_ctrl_hevc_scaling_matrix(9)
• struct v4l2_vp9_quantization(9)
• struct v4l2_vp9_segmentation(9)
• struct v4l2_ctrl_vp9_frame(9)
• struct v4l2_vp9_mv_probs(9)
• struct v4l2_ctrl_vp9_compressed_hdr(9)
• struct v4l2_ctrl_av1_sequence(9)
• struct v4l2_ctrl_av1_tile_group_entry(9)
• enum v4l2_av1_warp_model(9)
• enum v4l2_av1_reference_frame(9)
• struct v4l2_av1_global_motion(9)
• enum v4l2_av1_frame_restoration_type(9)
• struct v4l2_av1_loop_restoration(9)
• struct v4l2_av1_cdef(9)
• enum v4l2_av1_segment_feature(9)
• struct v4l2_av1_segmentation(9)
• struct v4l2_av1_loop_filter(9)
• struct v4l2_av1_quantization(9)
• struct v4l2_av1_tile_info(9)
• enum v4l2_av1_frame_type(9)
• enum v4l2_av1_interpolation_filter(9)
• enum v4l2_av1_tx_mode(9)
• struct v4l2_ctrl_av1_frame(9)
• struct v4l2_ctrl_av1_film_grain(9)

---

that's the whole page bestie, you ate that 🍓 and like, before you go — this little beauty lives in ./include/uapi/linux, dated October 2026, and it's called struct v4l2_vp9_loop_filter(9). mwah, go forth and zero your reserved fields 💖✨🎀