Question about DTV/bluray specs

Cristian Derois · December 29th, 2009, 06:44 AM

Hi folks, hope I posted at the right forum.

I have some issues about delivering HD content. To be practical, here you are:

1. Color corection: Does DTV broadcast needs IRE limits (say, 100 IRE for the brightest white and 0 IRE for the deepest dark)? I read a book entirely dedicated to HD postproduction and it didn't mentioned nothinh about this. This is little confused. LCD monitors works in RBG mode, isn't? So I dont know how to proceed to generate legal signals - because I didnt discover yet what is legal in DTV. ATSC table is a bit confusing, most what we see around relates to frame rate and resolution.

2. LCD monitors and tvs are progressive. That's ok, I'll made my bluray content in progressive frames. But what I couldn't figure out is about the frame rate. For exemple, 24 fps is related to TV itself or bluray media/player? It sounds silly, but I was unable to understand this issue. I know there's bluray playing movies at 24 fps, and, as far as I know, bluray player can play NTSC DVDs.

It is just two questions but I need to understand because all pipeline depends on this specs

Cristian

Robert M Wright · December 29th, 2009, 01:03 PM

The Blu-Ray specs allow for authoring and playback of disks that include true 24p content (as opposed to 24p content wrapped in a 60i stream). That doesn't have anything to do with what a TV can (or cannot) display.

Cristian Derois · December 29th, 2009, 02:01 PM

Thanks Robert

Randall Leong · December 29th, 2009, 09:19 PM

Also, if you're authoring 1080p content onto Blu-Ray, the frame rate support of such content is currently limited to 23.976/24 fps or 25 fps. In other words, if my video content is 1080/30p, then I either have to somehow convert (interpolate) that to 1080/24p or interlace (scan-convert) that to 1080/60i before I author this content onto Blu-Ray.

Robert M Wright · December 29th, 2009, 11:34 PM

Encoding 30p content as 60i doesn't usually get anymore involved than checking a box in your encoder's settings dialog. It's just not a big deal. The only real downside to Blu-Ray not supporting true 30p streams (either 720 or 1080 lines), is that 4:2:0 color isn't exactly ideal for interlaced video. Frankly, it's pretty lame that the Blu-Ray folks didn't include support for native 1080p30 and 720p30 video (which, perhaps not so ironically, doesn't affect the major motion picture studios one iota, but isn't being overly accommodating to the small independent professional videographer).

December 29th, 2009, 06:44 AM	#1
Cristian Derois Regular Crew Join Date: Nov 2009 Location: Porto Alegre, Brazil Posts: 28	Question about DTV/bluray specs - need some help Hi folks, hope I posted at the right forum. I have some issues about delivering HD content. To be practical, here you are: 1. Color corection: Does DTV broadcast needs IRE limits (say, 100 IRE for the brightest white and 0 IRE for the deepest dark)? I read a book entirely dedicated to HD postproduction and it didn't mentioned nothinh about this. This is little confused. LCD monitors works in RBG mode, isn't? So I dont know how to proceed to generate legal signals - because I didnt discover yet what is legal in DTV. ATSC table is a bit confusing, most what we see around relates to frame rate and resolution. 2. LCD monitors and tvs are progressive. That's ok, I'll made my bluray content in progressive frames. But what I couldn't figure out is about the frame rate. For exemple, 24 fps is related to TV itself or bluray media/player? It sounds silly, but I was unable to understand this issue. I know there's bluray playing movies at 24 fps, and, as far as I know, bluray player can play NTSC DVDs. It is just two questions but I need to understand because all pipeline depends on this specs Cristian

December 29th, 2009, 01:03 PM	#2
Robert M Wright Inner Circle Join Date: Jan 2006 Location: Minnesota (USA) Posts: 2,171	The Blu-Ray specs allow for authoring and playback of disks that include true 24p content (as opposed to 24p content wrapped in a 60i stream). That doesn't have anything to do with what a TV can (or cannot) display.

December 29th, 2009, 02:01 PM	#3
Cristian Derois Regular Crew Join Date: Nov 2009 Location: Porto Alegre, Brazil Posts: 28	Thanks Robert

December 29th, 2009, 09:19 PM	#4
Randall Leong Major Player Join Date: Nov 2009 Location: Melrose Park, Illinois, USA Posts: 936	Also, if you're authoring 1080p content onto Blu-Ray, the frame rate support of such content is currently limited to 23.976/24 fps or 25 fps. In other words, if my video content is 1080/30p, then I either have to somehow convert (interpolate) that to 1080/24p or interlace (scan-convert) that to 1080/60i before I author this content onto Blu-Ray.

December 29th, 2009, 11:34 PM	#5
Robert M Wright Inner Circle Join Date: Jan 2006 Location: Minnesota (USA) Posts: 2,171	Encoding 30p content as 60i doesn't usually get anymore involved than checking a box in your encoder's settings dialog. It's just not a big deal. The only real downside to Blu-Ray not supporting true 30p streams (either 720 or 1080 lines), is that 4:2:0 color isn't exactly ideal for interlaced video. Frankly, it's pretty lame that the Blu-Ray folks didn't include support for native 1080p30 and 720p30 video (which, perhaps not so ironically, doesn't affect the major motion picture studios one iota, but isn't being overly accommodating to the small independent professional videographer).