[FFmpeg-devel] [PATCH] avcodec/cbs_av1: add support for Scalability Metadata

Mark Thompson sw at jkqxz.net
Wed Apr 17 01:05:51 EEST 2019


On 14/04/2019 23:04, James Almer wrote:
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
> This will make the AV1RawObu struct weigh about ~3kb instead of ~1kb.
> 
>  libavcodec/av1.h                     | 33 ++++++++++++++++++++
>  libavcodec/cbs_av1.h                 | 15 +++++++++-
>  libavcodec/cbs_av1_syntax_template.c | 45 ++++++++++++++++++++++++++--
>  3 files changed, 90 insertions(+), 3 deletions(-)
> 
> diff --git a/libavcodec/av1.h b/libavcodec/av1.h
> index f2ec39c86b..6c0e32485b 100644
> --- a/libavcodec/av1.h
> +++ b/libavcodec/av1.h
> @@ -127,4 +127,37 @@ enum {
>      AV1_CSP_COLOCATED = 2, // -> AVCHROMA_LOC_TOPLEFT.
>  };
>  
> +// Scalability modes (section 6.7.5)
> +enum {
> +    AV1_SCALABILITY_L1T2 = 0,
> +    AV1_SCALABILITY_L1T3 = 1,
> +    AV1_SCALABILITY_L2T1 = 2,
> +    AV1_SCALABILITY_L2T2 = 3,
> +    AV1_SCALABILITY_L2T3 = 4,
> +    AV1_SCALABILITY_S2T1 = 5,
> +    AV1_SCALABILITY_S2T2 = 6,
> +    AV1_SCALABILITY_S2T3 = 7,
> +    AV1_SCALABILITY_L2T1h = 8,
> +    AV1_SCALABILITY_L2T2h = 9,
> +    AV1_SCALABILITY_L2T3h = 10,
> +    AV1_SCALABILITY_S2T1h = 11,
> +    AV1_SCALABILITY_S2T2h = 12,
> +    AV1_SCALABILITY_S2T3h = 13,
> +    AV1_SCALABILITY_SS = 14,
> +    AV1_SCALABILITY_L3T1 = 15,
> +    AV1_SCALABILITY_L3T2 = 16,
> +    AV1_SCALABILITY_L3T3 = 17,
> +    AV1_SCALABILITY_S3T1 = 18,
> +    AV1_SCALABILITY_S3T2 = 19,
> +    AV1_SCALABILITY_S3T3 = 20,
> +    AV1_SCALABILITY_L3T2_KEY = 21,
> +    AV1_SCALABILITY_L3T3_KEY = 22,
> +    AV1_SCALABILITY_L4T5_KEY = 23,
> +    AV1_SCALABILITY_L4T7_KEY = 24,
> +    AV1_SCALABILITY_L3T2_KEY_SHIFT = 25,
> +    AV1_SCALABILITY_L3T3_KEY_SHIFT = 26,
> +    AV1_SCALABILITY_L4T5_KEY_SHIFT = 27,
> +    AV1_SCALABILITY_L4T7_KEY_SHIFT = 28,
> +};
> +
>  #endif /* AVCODEC_AV1_H */
> diff --git a/libavcodec/cbs_av1.h b/libavcodec/cbs_av1.h
> index e799964b72..1fb668ada4 100644
> --- a/libavcodec/cbs_av1.h
> +++ b/libavcodec/cbs_av1.h
> @@ -325,7 +325,20 @@ typedef struct AV1RawMetadataHDRMDCV {
>  
>  typedef struct AV1RawMetadataScalability {
>      uint8_t scalability_mode_idc;
> -    // TODO: more stuff.
> +    uint8_t spatial_layers_cnt_minus_1;
> +    uint8_t spatial_layer_dimensions_present_flag;
> +    uint8_t spatial_layer_description_present_flag;
> +    uint8_t temporal_group_description_present_flag;
> +    uint8_t scalability_structure_reserved_3bits;
> +    uint16_t spatial_layer_max_width[4];
> +    uint16_t spatial_layer_max_height[4];
> +    uint8_t spatial_layer_ref_id[4];
> +    uint8_t temporal_group_size;
> +    uint8_t temporal_group_temporal_id[255];
> +    uint8_t temporal_group_temporal_switching_up_point_flag[255];
> +    uint8_t temporal_group_spatial_switching_up_point_flag[255];
> +    uint8_t temporal_group_ref_cnt[255];
> +    uint8_t temporal_group_ref_pic_diff[255][7];
>  } AV1RawMetadataScalability;
>  
>  typedef struct AV1RawMetadataITUTT35 {
> diff --git a/libavcodec/cbs_av1_syntax_template.c b/libavcodec/cbs_av1_syntax_template.c
> index 0e019aa113..ef48173470 100644
> --- a/libavcodec/cbs_av1_syntax_template.c
> +++ b/libavcodec/cbs_av1_syntax_template.c
> @@ -1653,12 +1653,53 @@ static int FUNC(metadata_hdr_mdcv)(CodedBitstreamContext *ctx, RWContext *rw,
>      return 0;
>  }
>  
> +static int FUNC(scalability_structure)(CodedBitstreamContext *ctx, RWContext *rw,
> +                                       AV1RawMetadataScalability *current)
> +{
> +    int err, i, j;
> +
> +    fb(2, spatial_layers_cnt_minus_1);
> +    flag(spatial_layer_dimensions_present_flag);
> +    flag(spatial_layer_description_present_flag);
> +    flag(temporal_group_description_present_flag);
> +    fc(3, scalability_structure_reserved_3bits, 0, 0);
> +    if (current->spatial_layer_dimensions_present_flag) {
> +        for (i = 0; i <= current->spatial_layers_cnt_minus_1; i++) {
> +            fbs(16, spatial_layer_max_width[i], 1, i);
> +            fbs(16, spatial_layer_max_height[i], 1, i);

Can we verify against the "must not be larger than max_frame_*_minus_1 + 1" constraint here?  (I think a sequence header should be available.)

> +        }
> +    }
> +    if (current->spatial_layer_description_present_flag) {
> +        for (i = 0; i <= current->spatial_layers_cnt_minus_1; i++)
> +            fbs(8, spatial_layer_ref_id[i], 1, i);
> +    }
> +    if (current->temporal_group_description_present_flag) {
> +        fb(8, temporal_group_size);
> +        for (i = 0; i < current->temporal_group_size; i++) {
> +            fbs(3, temporal_group_temporal_id[i], 1, i);
> +            flags(temporal_group_temporal_switching_up_point_flag[i], 1, i);
> +            flags(temporal_group_spatial_switching_up_point_flag[i], 1, i);
> +            fbs(3, temporal_group_ref_cnt[i], 1, i);
> +            for (j = 0; j < current->temporal_group_ref_cnt[i]; j++) {
> +                fbs(8, temporal_group_ref_pic_diff[i][j], 2, i, j);
> +            }
> +        }
> +    }
> +
> +    return 0;
> +}
> +
>  static int FUNC(metadata_scalability)(CodedBitstreamContext *ctx, RWContext *rw,
>                                        AV1RawMetadataScalability *current)
>  {
> -    // TODO: scalability metadata.
> +    int err;
>  
> -    return AVERROR_PATCHWELCOME;
> +    fb(8, scalability_mode_idc);
> +
> +    if (current->scalability_mode_idc == AV1_SCALABILITY_SS)
> +        CHECK(FUNC(scalability_structure)(ctx, rw, current));
> +
> +    return 0;
>  }
>  
>  static int FUNC(metadata_itut_t35)(CodedBitstreamContext *ctx, RWContext *rw,
> 

Looks fine.

Thanks,

- Mark


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