Before I attempt to correspond with Charles Poynton, I want to give folks the opportunity to correct what I've written and to make additions.
I plan to seek Charles Poynton's comments. I plan to ask specifically about his 4:2:2, 4:2:0, and 4:1:1, and whether Chroma_subsampling_notation.pdf assumes subpixel dither and averaging without saying so. --Mark. References: Wikipedia: https://en.wikipedia.org/wiki/Chroma_subsampling Poynton: https://www.poynton.ca/PDFs/Chroma_subsampling_notation.pdf KEY: '•' : denotes a luma locus (i.e. a physical pixel location). '©' : denotes a chroma locus. '—' : there is no field there [1]. '©=©' : a single Cb Cr pair spans 2 pixels. '©=©=©=©' : a single Cb Cr pair spans 4 pixels. [1] There is no field data (i.e. no chroma pixels) for this field. If there is a first chroma field, the decoder copies it to the second chroma field, effectively halving vertical resolution for that chroma. If there is no first field (e.g. 4:0:0), then there are no chroma fields and composited pixels carry luma only. Shown next is the top-left corner of the sampled film. +—————————— | ¤ ¤ ¤ ¤ RGB samples | ¤ ¤ ¤ ¤ RGB samples | Shown next is Y, Cb, and Cr separated as element 'planes'. | Y Cb Cr | • • • • | © © © © | © © © © 4:4:4 | • • • • | © © © © | © © © © Poynton, Wikipedia | • • • • | © © © © | © © © © 4:4:2 | • • • • | ©=© ©=© | ©=© ©=© My conjecture | • • • • | © © © © | © © © © 4:4:1 | • • • • | ©=©=©=© | ©=©=©=© My conjecture | • • • • | © © © © | © © © © 4:4:0 | • • • • |———————— |———————— Wikipedia | • • • • | ©=© ©=© | ©=© ©=© 4:2:2 | • • • • | ©=© ©=© | ©=© ©=© Wikipedia | | +-- center is coincident with Y0(?) | | ¦ | .-- center is coincident with Y0(?) | • • |©=©• |©=©• 4:2:2 (BT.601) | • • |©=©• |©=©• Poynton | • • • • | ©=© ©=© | ©=© ©=© 4:2:1 | • • • • | ©=©=©=© | ©=©=©=© My conjecture | • • • • | ©=© ©=© | ©=© ©=© 4:2:1 (JPEG variant) | • • • • |———————— | ©=©=©=© Wikipedia | • • • • | ©=© ©=© | ©=© ©=© 4:2:0 (MPEG1, H.261) | • • • • |———————— |———————— Wikipedia | • • | ©=© | ©=© 4:2:0 (MPEG1, H.261) | • • |———— |———— Poynton | | +-- center is coincident with Y0(?) | | ¦ | .-- center is coincident with Y0(?) | • • |©=©• |©=©• 4:2:0 (MPEG2 frames) | • • |———— |———— Poynton | • • • • | ©=©=©=© | ©=©=©=© 4:1:1 | • • • • | ©=©=©=© | ©=©=©=© Wikipedia | | +-- center is coincident with Y0(?) | | ¦ | .-- center is coincident with Y2(?) | • • • • ©=©=©=©• • | •©=©=©=© 4:1:1 (480i) | • • • • ©=©=©=©• • | •©=©=©=© Poynton | • • • • |©=©=©=©• | •©=©=©=© 4:1:0 | • • • • |———————— |————————— My conjecture | • • • • |————————— |————————— 4:0:0 | • • • • |————————— |————————— My conjecture (monochrome) | • • • | ©=©=© | ©=©=© 3:1:1 (Sony) | • • • | ©=©=© | ©=©=© Poynton _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
