On Sun, Mar 9, 2025 at 9:57 PM Nuo Mi <nuomi2...@gmail.com> wrote:
>
>
> 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(-)
>>
>> 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++;
>> + }
>>
> Hi Frank,
> Thank you for the v2.
> Same logic as width_in_tiles, with only a few different parameters. Better
> to avoid duplication.
> How about using a single function: size_in_tiles(size_in_ctu, top_left,
> tile_val, num_tile)?
>
Hmm, it's in CBS. Sorry, you can ignore the suggestion.
There's a lot of duplicate code in CBS—I tried to refactor it into
functions, but Mark objected
Will push this version later.
> +
>> + 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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