[FFmpeg-devel] [PATCH 5/8] lavc/hevc_ps: parse constraint flags for HEVC REXT

[Mark Thompson]

On 29/12/2019 16:30, Linjie Fu wrote:
> Parse all the constraint flags according to ITU-T Rec. H.265 (02/2018).
> 
> They have to be passed to hw decoders to determine the exact profile for Range
> Extension HEVC.
> 
> Signed-off-by: Linjie Fu <linjie.fu at intel.com>
> ---
>  libavcodec/hevc_ps.c | 44 ++++++++++++++++++++++++++++++++++++++++----
>  libavcodec/hevc_ps.h | 13 ++++++++++++-
>  2 files changed, 52 insertions(+), 5 deletions(-)
> 
> diff --git a/libavcodec/hevc_ps.c b/libavcodec/hevc_ps.c
> index a30b8b8..87a1da1 100644
> --- a/libavcodec/hevc_ps.c
> +++ b/libavcodec/hevc_ps.c
> @@ -267,7 +267,7 @@ static int decode_profile_tier_level(GetBitContext *gb, AVCodecContext *avctx,
>  {
>      int i;
>  
> -    if (get_bits_left(gb) < 2+1+5 + 32 + 4 + 16 + 16 + 12)
> +    if (get_bits_left(gb) < 2+1+5 + 32 + 4 + 43 + 1)
>          return -1;
>  
>      ptl->profile_space = get_bits(gb, 2);
> @@ -295,9 +295,45 @@ static int decode_profile_tier_level(GetBitContext *gb, AVCodecContext *avctx,
>      ptl->non_packed_constraint_flag = get_bits1(gb);
>      ptl->frame_only_constraint_flag = get_bits1(gb);
>  
> -    skip_bits(gb, 16); // XXX_reserved_zero_44bits[0..15]
> -    skip_bits(gb, 16); // XXX_reserved_zero_44bits[16..31]
> -    skip_bits(gb, 12); // XXX_reserved_zero_44bits[32..43]
> +#define check_profile_idc(idc) \
> +        ptl->profile_idc == idc || ptl->profile_compatibility_flag[idc]
> +
> +    if (check_profile_idc(4) || check_profile_idc(5) || check_profile_idc(6) ||
> +        check_profile_idc(7) || check_profile_idc(8) || check_profile_idc(9) ||
> +        check_profile_idc(10)) {
> +
> +        ptl->max_12bit_constraint_flag        = get_bits1(gb);
> +        ptl->max_10bit_constraint_flag        = get_bits1(gb);
> +        ptl->max_8bit_constraint_flag         = get_bits1(gb);
> +        ptl->max_422chroma_constraint_flag    = get_bits1(gb);
> +        ptl->max_420chroma_constraint_flag    = get_bits1(gb);
> +        ptl->max_monochrome_constraint_flag   = get_bits1(gb);
> +        ptl->intra_constraint_flag            = get_bits1(gb);
> +        ptl->one_picture_only_constraint_flag = get_bits1(gb);
> +        ptl->lower_bit_rate_constraint_flag   = get_bits1(gb);
> +
> +        if (check_profile_idc(5) || check_profile_idc(9) || check_profile_idc(10)) {
> +            ptl->max_14bit_constraint_flag    = get_bits1(gb);
> +            skip_bits_long(gb, 33); // XXX_reserved_zero_33bits[0..32]
> +        } else {
> +            skip_bits_long(gb, 34); // XXX_reserved_zero_34bits[0..33]
> +        }
> +    } else if (check_profile_idc(2)) {
> +        skip_bits(gb, 7);
> +        ptl->one_picture_only_constraint_flag = get_bits1(gb);
> +        skip_bits_long(gb, 35); // XXX_reserved_zero_35bits[0..34]
> +    } else {
> +        skip_bits_long(gb, 43); // XXX_reserved_zero_43bits[0..42]
> +    }
> +
> +    if ((ptl->profile_idc >=1 && ptl->profile_idc <= 5) || ptl->profile_idc == 9 ||
> +        ptl->profile_compatibility_flag[1] || ptl->profile_compatibility_flag[2] ||
> +        ptl->profile_compatibility_flag[3] || ptl->profile_compatibility_flag[4] ||
> +        ptl->profile_compatibility_flag[5] || ptl->profile_compatibility_flag[9])

Your check_profile_idc() macro from above would make this test slightly clearer.

> +        ptl->inbld_flag = get_bits1(gb);
> +    else
> +        skip_bits1(gb);
> +#undef check_profile_idc
>  
>      return 0;
>  }
> diff --git a/libavcodec/hevc_ps.h b/libavcodec/hevc_ps.h
> index 2840dc4..8e1bccd 100644
> --- a/libavcodec/hevc_ps.h
> +++ b/libavcodec/hevc_ps.h
> @@ -177,11 +177,22 @@ typedef struct PTLCommon {
>      uint8_t tier_flag;
>      uint8_t profile_idc;
>      uint8_t profile_compatibility_flag[32];
> -    uint8_t level_idc;
>      uint8_t progressive_source_flag;
>      uint8_t interlaced_source_flag;
>      uint8_t non_packed_constraint_flag;
>      uint8_t frame_only_constraint_flag;
> +    uint8_t max_12bit_constraint_flag;
> +    uint8_t max_10bit_constraint_flag;
> +    uint8_t max_8bit_constraint_flag;
> +    uint8_t max_422chroma_constraint_flag;
> +    uint8_t max_420chroma_constraint_flag;
> +    uint8_t max_monochrome_constraint_flag;
> +    uint8_t intra_constraint_flag;
> +    uint8_t one_picture_only_constraint_flag;
> +    uint8_t lower_bit_rate_constraint_flag;
> +    uint8_t max_14bit_constraint_flag;
> +    uint8_t inbld_flag;
> +    uint8_t level_idc;
>  } PTLCommon;
>  
>  typedef struct PTL {
> 
- Mark