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

[James Almer]

On 4/16/2019 7:05 PM, Mark Thompson wrote:
> 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.)

Ah, good catch. Added a check for that.
> 
>> +        }
>> +    }
>> +    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

Pushed, thanks!