[FFmpeg-devel] [PATCH v2 01/11] avcodec/vvc: add shared header for vvc

[Nuo Mi]

How about we define it as 20,  check the size and return error if > 20.
20 should enough for most of clips. hevc used 20.

On Sun, Jan 10, 2021 at 9:39 AM Nuo Mi <nuomi2021 at gmail.com> wrote:

>
>
> On Sun, Jan 10, 2021 at 3:09 AM Mark Thompson <sw at jkqxz.net> wrote:
>
>> On 09/01/2021 07:34, Nuo Mi wrote:
>> > ---
>> >   libavcodec/vvc.h | 124 +++++++++++++++++++++++++++++++++++++++++++++++
>> >   1 file changed, 124 insertions(+)
>> >   create mode 100644 libavcodec/vvc.h
>> >
>> > diff --git a/libavcodec/vvc.h b/libavcodec/vvc.h
>> > new file mode 100644
>> > index 0000000000..0bd2acac1d
>> > --- /dev/null
>> > +++ b/libavcodec/vvc.h
>> > @@ -0,0 +1,124 @@
>> > ...
>> > +
>> > +enum {
>> > +    VVC_MAX_PLANES = 3,
>>
>> MAX_SAMPLE_ARRAYS, with reference to 6.2?  The term "plane" is never used
>> in the specification at all.
>>
>> > +    //7.4.3.3 The value of vps_max_sublayers_minus1 shall be in the
>> range of 0 to 6, inclusive
>> > +    VVC_MAX_SUBLAYERS = 7,
>> > +
>> > +    // 7.3.2.3: vps_video_parameter_set_id is u(4).
>> > +    VVC_MAX_VPS_COUNT = 16,
>> > +    // 7.3.2.4: sps_seq_parameter_set_id is u(4)
>> > +    VVC_MAX_SPS_COUNT = 16,
>> > +    // 7.3.2.5: pps_pic_parameter_set_id is u(6)
>> > +    VVC_MAX_PPS_COUNT = 64,
>> > +
>> > +    // 7.4.4.1: ptl_num_sub_profiles is u(8)
>> > +    VVC_MAX_SUB_PROFILES = 256,
>> > +
>> > +    // A.4.2: according to (1577), MaxDpbSize is bounded above by 2 *
>> maxDpbPicBuf(8)
>> > +    VVC_MAX_DPB_SIZE = 16,
>> > +
>> > +    //7.4.3.4 sps_num_ref_pic_lists in range [0, 64]
>> > +    VVC_MAX_REF_PIC_LISTS = 64,
>> > +
>> > +    //7.4.3.3 sps_num_points_in_qp_table_minus1[i] in range [0, 36 −
>> sps_qp_table_start_minus26[i]],
>> > +    //sps_qp_table_start_minus26[i] in range
>> [sps_qp_table_start_minus26[i] −26 − QpBdOffset, 36]
>> > +    //for 10 bitsQpBdOffset is 12, so
>> sps_num_points_in_qp_table_minus1[i] in range [0, 74]
>> > +    VVC_MAX_POINTS_IN_QP_TABLE = 75,
>> > +
>> > +    // 7.4.6.1: hrd_cpb_cnt_minus1 is in [0, 31].
>> > +    VVC_MAX_CPB_CNT = 32,
>> > +
>> > +    // A.4.1: the highest level allows a MaxLumaPs of 35 651 584.
>> > +    VVC_MAX_LUMA_PS = 35651584,
>> > +    // A.4.1: pic_width_in_luma_samples and pic_height_in_luma_samples
>> are
>> > +    // constrained to be not greater than sqrt(MaxLumaPs * 8).  Hence
>> height/
>> > +    // width are bounded above by sqrt(8 * 35651584) = 16888.2 samples.
>> > +    VVC_MAX_WIDTH  = 16888,
>> > +    VVC_MAX_HEIGHT = 16888,
>> > +
>> > +    // A.4.1: table A.1 allows at most 440 tiles for any au.
>> > +    VVC_MAX_TILE_ROWS    = 440,
>>
>> Is this bound really the best we can do?
>>
>> That is, is it actually possible to construct a valid stream with 440
>> tile rows?  It must have a single tile column and a height of at least
>> 14080 (for 440 rows of 32x32 CTUs), which feels extreme enough that it
>> might hit some of the other level constraints.
>>
> The  VVC_MAX_HEIGHT is 16888, it's higher than 14080.
> If we limit the VVC_MAX_HEIGHT to 4k, we can reduce it to 135.
>
>>
>> > +    // A.4.1: table A.1 allows at most 20 tile columns for any level.
>> > +    VVC_MAX_TILE_COLUMNS = 20,
>> > +
>> > +    // A.4.1 table A.1 allows at most 600 slice for any level.
>> > +    VVC_MAX_SLICES = 600,
>> > +
>> > +    // 7.4.8: in the worst case (tiles_enabled_flag and
>> > +    // entropy_coding_sync_enabled_flag are both set), entry points
>> can be
>> > +    // placed at the beginning of every Ctb row in every tile, giving
>> an
>> > +    // upper bound of (num_tile_columns_minus1 + 1) * PicHeightInCtbsY
>> - 1.
>> > +    // Only a stream with very high resolution and perverse parameters
>> could
>> > +    // get near that, though, so set a lower limit here with the
>> maximum
>> > +    // possible value for 8K video (at most 135 32x32 Ctb rows).
>> > +    VVC_MAX_ENTRY_POINTS = VVC_MAX_TILE_COLUMNS * 135,
>> > +};
>> > +
>> > +#endif /* AVCODEC_VVC_H */
>>
>> - Mark
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>