[FFmpeg-devel] [PATCH 3/6] lavc/vvc: Store MIP information over entire CU area

[Nuo Mi]

On Fri, Nov 29, 2024 at 6:19 AM Frank Plowman <post at frankplowman.com> wrote:

> Previously, the code only stored the MIP mode and transpose flag in the
> relevant tables at the top-left corner of the CU.  This information ends
> up being retrieved in ff_vvc_intra_pred_* not based on the CU position
> but instead the transform unit position (specifically, using the x0 and
> y0 from get_luma_predict_unit).  There might be multiple transform units
> in a CU, hence the top-left corner of the transform unit might not
> coincide with the top-left corner of the CU.  Consequently, we need to
> store the MIP information at all positions in the CU, not only its
> top-left corner, as we already do for the MIP flag.
>
> Signed-off-by: Frank Plowman <post at frankplowman.com>
> ---
>  libavcodec/vvc/ctu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/libavcodec/vvc/ctu.c b/libavcodec/vvc/ctu.c
> index 1e06119cfd..0030938cf5 100644
> --- a/libavcodec/vvc/ctu.c
> +++ b/libavcodec/vvc/ctu.c
> @@ -975,8 +975,8 @@ static void intra_luma_pred_modes(VVCLocalContext *lc)
>              for (int y = 0; y < (cb_height>>log2_min_cb_size); y++) {
>                  int width = cb_width>>log2_min_cb_size;
>                  memset(&fc->tab.imf[x],  cu->intra_mip_flag, width);
> -                fc->tab.imtf[x] = intra_mip_transposed_flag;
> -                fc->tab.imm[x]  = intra_mip_mode;
> +                memset(&fc->tab.imtf[x], intra_mip_transposed_flag,
> width);
> +                memset(&fc->tab.imm[x], intra_mip_mode, width);

 intra_mip_mode is 4 bits, 2 flags are 2 bits. maybe we can use a uint8_t
for 3 fields,
We only need 1 memset and save 2/3 memory.

>

                 x += pps->min_cb_width;
>              }
>              cu->intra_pred_mode_y = intra_mip_mode;
> --
> 2.47.0
>
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