720p30?

[Jeff Hartman]

[Bret Williams] “I understand that 720p is really always 60p as far as the output of the device goes (has to be 60hz somehow) but the sequence doesn’t need to be 60p. That just adds overhead to the processor.”

Perhaps I’m misunderstanding what you mean… but 720p/60 (actually 59.94) is indeed 60 unique frames per second; it isn’t meaningless overhead at all. It still takes a while for those of us to have done interlaced NTSC for decades to get used to it…

I find that thinking of it strictly from a broadcast perspective helps:

• 720p provides sixty complete 1280×720 frames every second.

• 1080i provides thirty complete 1980×1080 frames every second (broken up into sixty interlaced fields). Each complete 1080i frame consists of slightly more than twice as many pixels as one 720p frame; since 1080i transmits half as many complete frames as 720p per second, the net result in data rate is close enough that either format can be practically encoded within an ATSC channel; this also accounts for either format being supported by 1.485Gb/s HD-SDI cabling and equipment.

• 1080p provides sixty complete 1980×1080 frames every second — that is, the same frame rate as 720p, and the same screen resolution as 1080i. As you would expect, since the number of complete 1080p frames is twice 1080i, the data rate doubles — and requires a 3G connection.

Other frame rates — 1080p/24, for instance — are targeted more at electronic cinema applications rather than broadcast… but you can infer the lower storage and processing requirements, compared with 1080p/60.

Regards,

— Jeff

[Bret Williams]

You are misunderstanding. I understand all of that completely. But obviously a lot of people shoot 30p and there are plentiful of easy setups in FCP and Premiere for it with Matrox and other drivers. Blackmagic only supplies easy setups for the congenital broadcast formats. 720p60, 1080p24, and 1080i60. If you shot 720p30, it it excessive overhead to edit in a 720p60 sequence, doubling the size of your renders and forcing the processor to play back 60fps instead of 30. The intensity extreme may very well do a hardware conversion to 60p just to keep the 60hz for the TV, I dunno.

So now I forget. What was my question? Oh, yeah, why such limited presets? Matrox has a zillion more. Every config you can think of, and every ProRes codec for every config. You never need to set anything manually, which seems to be the downfall of so many.

[Jeff Hartman]

[Bret Williams] “You are misunderstanding. I understand all of that completely. But obviously a lot of people shoot 30p and there are plentiful of easy setups in FCP and Premiere for it with Matrox and other drivers. Blackmagic only supplies easy setups for the congenital broadcast formats. 720p60, 1080p24, and 1080i60. If you shot 720p30, it it excessive overhead to edit in a 720p60 sequence, doubling the size of your renders and forcing the processor to play back 60fps instead of 30. The intensity extreme may very well do a hardware conversion to 60p just to keep the 60hz for the TV, I dunno.

So now I forget. What was my question? Oh, yeah, why such limited presets? Matrox has a zillion more. Every config you can think of, and every ProRes codec for every config. You never need to set anything manually, which seems to be the downfall of so many.”

You are indeed correct, and I missed the premise that you were actually shooting 30fps… perhaps because I had a nearly identical conversation with one of our people about a month ago.

Putting on my design hat for a moment, the only reason I can think of for the limited selection is that possibly the options are constrained by the hardware, not the software. My guess is that Blackmagic tends to create products by starting with existing hardware (i.e. chipsets) and then writing software to produce specific functionality — as opposed to designing their own hardware from the ground up. Using already available chips really drives down the cost of development, but sometimes creates unforeseen limitations when software can’t quite accomplish everything you want the product to do.

— Jeff

[Bret Williams]

True, except this is just a matter of laziness and them not creating the presets. For example, the Matrox 720p30 preset is just a easy setup. Every new sequence you create is 720p30. The hardware still outputs 720p60 of course. But it doesn’t create 60p video files.

The same is true of BlackMagic. You can change the sequence settings manually no problem. But that greatly increases the chance of user error. I’m just baffled as to why they don’t create these presets.

[Jason Byfield]

I work in the video game industry and our game engine outputs 720p30 so whenever I capture via HDMI using the available 720p60 preset, I’m essentially doubling the data that I need (every other frame is a duplicate). Just chiming in here in the hopes that BM will come across it and realize that more than just broadcast professionals use their equipment.

[Brian Smith]

This thread is obviously not going any further, but since I just discovered it….

[Jason Byfield] “Just chiming in here in the hopes that BM will come across it and realize that more than just broadcast professionals use their equipment.”

I second that. I work almost exclusively with animation. All of which is output at a straight 30fps. All of the content we create lives online, never broadcast. I still have the same need for a quality output for internal/client reviews. Our clients generally don’t have the budget (or the need) for us to work in 1080p.