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by keithwinstein 1069 days ago
Just to be pedantic, 1080p24 (and 1080p30, and the 1000/1001-rate versions) are already allowed by the existing A/53 spec and have been since 1995. The big (1080-line) broadcasters usually transmit their film-style programming as "effectively" 1080p24, in the sense that they're sending 24 or 24000/1001 progressive-scan coded pictures per second, but with flags that ask the decoder to perform a 3:2 pulldown to output 60 fields per second so it fits seamlessly within a 1080i30 sequence. (They could be sending "true" 1080p24, but then it would probably create a glitch when they transition to 60 fps content and back.)

But anyway: 1080p itself is not a new feature of ATSC 3.0. 1080p60 or 1080p120, sure.
1 comments
cjensen 1069 days ago
A bit of a nitpick: 1080p24 was added in 2008 along with h.264. It was not part of the original spec, so the original HDTV sets could not decode it. Broadcasters sensibly don't send 1080p24 since 1080p60 is "good enough" and works on all TVs.
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keithwinstein 1057 days ago
Not so -- 1080p24 and 1080p30 sequences (and the 1000/1001-rate versions) were part of the original A/53 specification in 1995. This is for H.262 video (MPEG-2 part 2). It's also in the 2007 revision (see A/53:2007 part 4, table 6.1.2 [1]). In practice, what broadcasters really do is send a sequence labeled 1080i30 for everything, but during the 24P content, they send 24 progressive-scan frame pictures per second, with picture flags that instruct the decoder how to perform the 3:2 pulldown to manufacture 60 fields per second at the receiver. This kind of "1080p24" is very common and they've been doing it since the 90s or early 2000s. The same basic technique is used on NTSC DVDs.

([1] https://prdatsc.wpenginepowered.com/wp-content/uploads/2021/.... Pedantic note: What the FCC adopted is slightly more generous than the ATSC spec; they excluded this table, both pre- and post-2007. So technically speaking, anything "Main Profile @ High Level" is allowed on the U.S. airwaves, but it doesn't matter in practice.)

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toast0 1069 days ago
If you're nitpicking, I think you mean 1080i60 is good enough.
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