> On Dec 21, 2022, at 02:24, Tomas Härdin <g...@haerdin.se> wrote: > > tor 2022-12-15 klockan 01:37 +0800 skrev Zhao Zhili: >> On Wed, 2022-12-14 at 18:08 +0100, Tomas Härdin wrote: >> >>> >>> I think we might want something for this inside lavf somewhere, so >>> that >>> encoders can signal dimension alignment requirements. Some >>> containers >>> (MXF, MOV) support such cropping in a codec-agnostic manner. >> >> From my own experience, dimension mismatch between codec and >> container >> makes a lot of trouble. ISO base format specification specified how >> to >> crop/scale after decoding clear, however, I don't think it has been >> widely supported, including FFmpeg. We can fix that inside of FFmpeg, >> but we should avoid such cases as much as we can. > > This is the difference between stored, sampled and display dimensions > in MXF. For example 1080i video has StoredHeight = 544, SampledHeight = > 540 and DisplayHeight = 540 (see AS-10). When you add VBLANK and HBLANK > to the mix then all three dimensions are typically different. > > Anyway specifying at the NAL level whenever the essence isn't a > multiple of 16x16 is obviously normal. The only complication I can > think of is 4:2:2 and 4:4:4. Does MC require 16x16 also in those cases? > I'd expect 16x8 and 8x8 respectively.
It’s still 16x16. From H.264 specification: macroblock: A 16x16 block of luma samples and two corresponding blocks of chroma samples of a picture that has three sample arrays, or a 16x16 block of samples of a monochrome picture or a picture that is coded using three separate colour planes. Macroblock has been replaced by coding tree unit with H.265, which can be between 16×16 pixels and 64×64 pixels in size. > > /Tomas > > _______________________________________________ > 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". _______________________________________________ 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".
