Bross, Benjamin: > 发件人: Bross, Benjamin <benjamin.br...@hhi.fraunhofer.de> > 发送时间: 2024年6月3日 3:42 > 收件人: FFmpeg development discussions and patches > 抄送: Wu Jianhua > 主题: Re: [FFmpeg-devel] [PATCH v2 3/3] tests/checkasm/vvc_alf: change alf step > size to 8 > >> From Benjamin Bross: >>> for ALF where functions are in increments of 4 while 8 should be sufficient >>> according to the spec. > > Actually, it is not only the increment but the size has to be a multiple of > 8, hence in addition loops should start at 8 instead of at 4. > > ALF filter and classification is applied on CTU-level. > According to VVC spec, CTU sizes can be: 32x32, 64x64, 128x128 luma samples. > However, if width or height are not a multiple of CTU size, the larger CTU is > "forced to split" until width or height fits. > E.g. width=840 luma samples fits 26.25 CTUs, i.e. 26 32x32 and one 8x32. > Width and height are restricted to be at least a multiple of 8 (see H.266 > 09/2023, 7.4.3.4 Sequence parameter set RBSP semantics)
> sps_pic_width_max_in_luma_samples shall not be equal to 0 and shall be an > integer multiple of > Max( 8, MinCbSizeY ) > … > sps_pic_height_max_in_luma_samples shall not be equal to 0 and shall be an > integer multiple of > Max( 8, MinCbSizeY ). > > Please note that this applies only for classification and 7x7 luma filtering. > For chroma 5x5 filtering and 420 subsampling, CTU sizes can be as small as > multiples of 4 chroma samples. Hi Benjamin, I will update some patches according to your comments. Thanks for your suggestion! Jianhua _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
