Steve Longerbeam <steve_longerbeam@xxxxxxxxxx> writes: > One final note, it is incorrect to assign 'seq-tb' to a PAL signal according > to this new understanding. Because according to various sites (for example > [1]), both standard definition NTSC and PAL are bottom field dominant, > so 'seq-tb' is not correct for PAL. Actually this isn't the case: - real PAL (= analog) is (was) interlaced, so you could choose any "dominant field" and it would work fine (stuff originating as film movies being an exception). - the general idea at these times was that NTSC-style digital video was bottom-first while PAL-style was top-first. - for example, most (practically all?) commercial TV-style interlaced PAL DVDs were top-first (movies were usually progressive). - standard TV (DVB 576i) uses (used) top-first as well. - this seems to be confirmed by e.g. ITU-R REC-BR.469-7-2002 (annex 1). Hovewer, this suggests that field 1 is the top one and 2 is bottom (and not first and second in terms of time). - if field 1 = top and 2 = bottom indeed, then we're back at BT.656 and my original idea that the SAV/EAV codes show straigh the so called odd/even lines and not some magic, standard-dependent lines of first and second fields. This needs to be verified. I think the ADV7180 forces the SAV/EAV codes (one can't set them depending od PAL/NTSC etc), so we could assume it does it right. - a notable exception to PAL = top first rule was DV and similar stuff (the casette camcorder things, including Digital8, miniDV, and probably derivatives). DV (including PAL) used bottom-first universally. I think we should stick to default PAL=TB, NTSC=BT rule, though the user should be able to override it (if working with e.g. PAL DV camcorder connected with an analog cable - not very probable, I guess). -- Krzysztof Halasa Industrial Research Institute for Automation and Measurements PIAP Al. Jerozolimskie 202, 02-486 Warsaw, Poland
