Folks,
A newbie question - When filling in an HDMI AVI infoframe, how does one
correctly determine the "default" picture aspect ratio (and VIC) for CEA modes
that support multiple (4:3 and 16:9) aspect ratios. 720x576p for example,
corresponds to VIC 17 or 18:
/* 17 - 720x576@50Hz */
{ DRM_MODE("720x576", DRM_MODE_TYPE_DRIVER, 27000, 720, 732,
796, 864, 0, 576, 581, 586, 625, 0,
DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC),
.vrefresh = 50, },
/* 18 - 720x576@50Hz */
{ DRM_MODE("720x576", DRM_MODE_TYPE_DRIVER, 27000, 720, 732,
796, 864, 0, 576, 581, 586, 625, 0,
DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC),
.vrefresh = 50, },
Should the "picture aspect ratio" information be derived from sink EDID (from
detailed/cvt/standard timings)? .. possibly in drm_add_edid_modes() and store
the picture aspect ratio in drm_display_mode perhaps, for later use? Trying to
get a better understanding of how this usually works.
As an aside, to match VIC correctly, shouldn't drm_match_cea_mode() take into
account picture aspect ratio as well?
Cheers,
Tushar
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