On Sun, Feb 23, 2025 at 8:05 PM Frank Plowman <p...@frankplowman.com> wrote:
> If pps_single_slice_per_subpic_flag is 1,
> slice_{width,height}_in_ctus 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>
> ---
> libavcodec/cbs_h266_syntax_template.c | 34 ++++++++++++++++++++++-----
> 1 file changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/libavcodec/cbs_h266_syntax_template.c
> b/libavcodec/cbs_h266_syntax_template.c
> index 58211026bb..b84f3e29db 100644
> --- a/libavcodec/cbs_h266_syntax_template.c
> +++ b/libavcodec/cbs_h266_syntax_template.c
> @@ -3440,13 +3440,35 @@ 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
> + height =
> pps->pps_slice_height_in_tiles_minus1[slice_idx] + 1;
>
pps_slice_height_in_tiles_minus1 is also undefined if
pps_single_slice_per_subpic_flag is true.
> + } 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
>
>
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
