| From: James Knott via talk <[email protected]>
|
| On 2023-06-19 14:47, D. Hugh Redelmeier via talk wrote:
| > One silly wast of bandwidth is blanking intervals. That mattered for CRTs
| > since steering the electron beam took time. It should not matter for
| > LCDs.
|
| That doesn't make sense, especially when you consider how the digital system
| works, with things like I, P and B frames.
| https://en.wikipedia.org/wiki/Video_compression_picture_types
Just because it no longer makes sense (I called it silly) doesn't make it
go away. But it may be vestigial. I don't yet know how to control it on
my Linux desktops.
Is such compression part of what HDMI carries? For computer monitors?
Almost all compression used in video is lossy -- not what I want for a
computer monitor
(My obsolete desktop monitor is a TV set. To get to 4k with HDMI 1.4 (or
was it 1.2?), it uses 4:2:2 chroma sub-sampling, a kind of compression.
This is looked down upon, to say the least.)
ATSC has compression. MPEG-n have compression. H.264 and H.265 have
compression. VP9 has compression. Each is lossy. But I don't think that
they are what flows over HDMI.
(There is compression coming for DisplayPort and HDMI standards to support
8k (DSC: Display Stream Compression). It is claimed to be "Visually
lossless" but I imagine that it isn't always lossless for computer monitor
use. <https://en.wikipedia.org/wiki/Display_Stream_Compression> )
| As you mentioned blanking intervals are a relic of analog TV, dating back
| before WW2. There is absolutely no need for them with digital TV.
Except varous things exploited them. Like whacking on GPU registers only
during blanking intervals to avoid tearing.
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