Can a frame use as reference a restricted picture with a non valid resolution ?

[forayr]

What version / commit were you testing with?

AVM v1.0

What is the problem?

For frame with implicit ref_frame_map, at the end of av2_get_ref_frames() (or get_ref_frames() in the spec), restricted reference pictures are added to remapped_ref_idx[]. When adding these frames, valid_ref_frame_size() is not called to check if the reference has a valid resolution even if resolution_available == 1, so the compliance of the scaling of restricted reference pictures is not checked.

However, later in read_uncompressed_frame(), the scale factors of each reference frame is checked, even if the reference is a restricted frame.

    if (!(current_frame->frame_type == INTRA_ONLY_FRAME) &&            
        pbi->need_resync != 1) {                                       
      for (int i = 0; i < cm->ref_frames_info.num_total_refs; ++i) {   
        const RefCntBuffer *const ref_buf = get_ref_frame_buf(cm, i);  
        if (!ref_buf) continue;                                        
        struct scale_factors *const ref_scale_factors =                
            get_ref_scale_factors(cm, i);                              
        av2_setup_scale_factors_for_frame(                             
            ref_scale_factors, ref_buf->buf.y_crop_width,              
            ref_buf->buf.y_crop_height, cm->width, cm->height);        
            ref_scale_factors->y_scale_fp);                            
        if ((!av2_is_valid_scale(ref_scale_factors)))                  
          avm_internal_error(&cm->error, AVM_CODEC_UNSUP_BITSTREAM,    
                             "Reference frame has invalid dimensions");
      }

It is then possible to generate a stream, especially when explicit_ref_frame_map = 0, that automatically add non valid restricted reference pictures, and which trigger this compliance check.

Am I missing an other specific compliance constraint ?

Else I think that either av2_get_ref_frames() should only add valid restricted frame, or that the compliance check should ignore restricted picture.

Additional information

Any other context / info that maybe useful.