On Thu, Mar 6, 2025 at 2:40 AM Frank Plowman <p...@frankplowman.com> wrote:
> If pps_single_slice_per_subpic_flag is 1,
> slice_{width,height}_in_tiles are undefined and we must instead get the
> dimensions of the slice by referring to the corresponding subpicture.
> Signed-off-by: Frank Plowman <p...@frankplowman.com>
> ---
> Changes since v1:
> * slice_height_in_tiles is also undefined if
> pps->pps_single_slice_per_subpic_flag is 1,
> so also derive that from the subpic info.
> ---
> libavcodec/cbs_h266_syntax_template.c | 49 +++++++++++++++++++++++----
> 1 file changed, 43 insertions(+), 6 deletions(-)
>
Applied.
Thank you, Frank.
>
> diff --git a/libavcodec/cbs_h266_syntax_template.c
> b/libavcodec/cbs_h266_syntax_template.c
> index 58211026bb..05634bc19c 100644
> --- a/libavcodec/cbs_h266_syntax_template.c
> +++ b/libavcodec/cbs_h266_syntax_template.c
> @@ -3440,13 +3440,50 @@ static int FUNC(slice_header)
> (CodedBitstreamContext *ctx, RWContext *rw,
> for (i = 0; i < current->curr_subpic_idx; i++) {
> slice_idx += pps->num_slices_in_subpic[i];
> }
> - width_in_tiles =
> - pps->pps_slice_width_in_tiles_minus1[slice_idx] + 1;
>
> - if (entropy_sync)
> - height = pps->slice_height_in_ctus[slice_idx];
> - else
> - height = pps->pps_slice_height_in_tiles_minus1[slice_idx]
> + 1;
> + if (pps->pps_single_slice_per_subpic_flag) {
> + const int width_in_ctus =
> sps->sps_subpic_width_minus1[slice_idx] + 1;
> + const int subpic_l =
> sps->sps_subpic_ctu_top_left_x[slice_idx];
> + const int subpic_r = subpic_l + width_in_ctus;
> +
> + int ctb_x = 0, tile_x = 0;
> + for (; ctb_x < subpic_l && tile_x <
> pps->num_tile_columns; tile_x++)
> + ctb_x += pps->col_width_val[tile_x];
> +
> + width_in_tiles = 0;
> + for (; ctb_x < subpic_r && tile_x <
> pps->num_tile_columns; tile_x++) {
> + ctb_x += pps->col_width_val[tile_x];
> + width_in_tiles++;
> + }
> +
> + if (entropy_sync)
> + height = sps->sps_subpic_height_minus1[slice_idx] + 1;
> + else {
> + const int height_in_ctus =
> sps->sps_subpic_height_minus1[slice_idx] + 1;
> + const int subpic_t =
> sps->sps_subpic_ctu_top_left_y[slice_idx];
> + const int subpic_b = subpic_t + height_in_ctus;
> +
> + int ctb_y = 0, tile_y = 0, height_in_tiles;
> + for (; ctb_y < subpic_t && tile_y <
> pps->num_tile_rows; tile_y++)
> + ctb_y += pps->row_height_val[tile_y];
> +
> + height_in_tiles = 0;
> + for (; ctb_y < subpic_b && tile_y <
> pps->num_tile_rows; tile_y++) {
> + ctb_y += pps->row_height_val[tile_y];
> + height_in_tiles++;
> + }
> +
> + height = height_in_tiles;
> + }
> + } else {
> + width_in_tiles =
> + pps->pps_slice_width_in_tiles_minus1[slice_idx] + 1;
> +
> + if (entropy_sync)
> + height = pps->slice_height_in_ctus[slice_idx];
> + else
> + height =
> pps->pps_slice_height_in_tiles_minus1[slice_idx] + 1;
> + }
>
> current->num_entry_points = width_in_tiles * height;
> } else {
> --
> 2.47.0
>
>
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