Le vendredi 22 mars 2019 à 16:42 +0200, Ville Syrjälä a écrit : > On Thu, Mar 21, 2019 at 03:14:06PM -0400, Nicolas Dufresne wrote: > > Le jeudi 21 mars 2019 à 18:35 +0200, Ville Syrjälä a écrit : > > > > I'm not sure what it's worth, but there is a "pixel format guide" > > > > project that is all about matching formats from one API to another: > > > > https://afrantzis.com/pixel-format-guide/ (and it has an associated > > > > tool too). > > > > > > > > On the page about DRM, it seems that they got the word that DRM formats > > > > are the native pixel order in little-endian systems: > > > > https://afrantzis.com/pixel-format-guide/drm.html > > > > > > Looks consistent with the official word in drm_fourcc.h. > > > > > > $ python3 -m pfg find-compatible V4L2_PIX_FMT_XBGR32 drm > > > Format: V4L2_PIX_FMT_XBGR32 > > > Is compatible on all systems with: > > > DRM_FORMAT_XRGB8888 > > > Is compatible on little-endian systems with: > > > Is compatible on big-endian systems with: > > > > > > $ python3 -m pfg find-compatible DRM_FORMAT_XRGB8888 v4l2 > > > Format: DRM_FORMAT_XRGB8888 > > > Is compatible on all systems with: > > > V4L2_PIX_FMT_XBGR32 > > > Is compatible on little-endian systems with: > > > Is compatible on big-endian systems with: > > > > > > Even works both ways :) > > > > > > > Perhaps some drivers have been abusing the format definitions, leading > > > > to the inconsistencies that Nicolas could witness? > > > > > > That is quite possible, perhaps even likely. No one really > > > seems interested in making sure big endian systems actually > > > work properly. I believe the usual approach is to hack > > > around semi-rnadomly until the correct colors accidentally > > > appear on the screen. > > > > We did not hack around randomly. > > BTW I didn't mean to imply it was you who hacked around randomly. > Sorry if you got that impression. > > What I was trying to convey is the following sequence of events: > 1. random person X gets their hand on a big endian machine for > a while > 2. colors are wrong > 3. they hack stuff until the colors are correct in their > current use case > 4. they move on to more interesting things Thanks for clarification. Nicolas
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