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Opitical Thunderbolt cables. On a Thinkpad.
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[Andrew Richards] “How fast is your RAID today?”
at 80% full:
Blackmagic Speed Utility: 1000 MBs Read; 831 MBs Write
AJA at 1280×720 8 bit: 978 MBs Read; 220 MBs Write (cache turned off)
And even at these speeds I get the green preview line for my 5 camera multicam timelines, using ProRes 720P60.
“I feel the need for speed.”
Herb Sevush
Zebra Productions
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nothin’ attached to nothin’
“Deciding the spine is the process of editing” F. Bieberkopf -
I understand, Andrew. Really, I get it.
But I’m not going to be doing 4k. There’s no reason in my line of work to post in 4k at this time.
We can shoot 4k, but I’m not posting in 4k, even so:
[Andrew Richards] “Even Pro Res 4K would be in the 500MB/sec range depending on the flavor.”
Who would 4k ProRes be any different from 1080 ProRes? ProRes and all of it’s variants have data rates. LT is 100 Mb/sec, ProRes is 145Mb/sec, HQ is 220Mb/sec and 444 is 330 Mb/sec at the very top level, those are bits, not Bytes. It’s a VBR codec so usually the rates are lower than that. So even if you saturate ProRes 444 at 4k, you are still well under 200MB/sec (big B).
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[Jeremy Garchow] “Who would 4k ProRes be any different from 1080 ProRes? “
It’s over 3 times the frame size, for one. Like pretty much any codec, the bitrate on ProRes is relative to the quality (4×4, HQ, etc), the frame size, and the frame rate. The bitrates are not absolute.
[Jeremy Garchow] “LT is 100 Mb/sec, ProRes is 145Mb/sec, HQ is 220Mb/sec and 444 is 330 Mb/sec at the very top level, those are bits, not Bytes. It’s a VBR codec so usually the rates are lower than that.”
Embarrassing mistake on my part, yes, bits not bytes. But those are the bitrates for 1080 @ 29.97. Everything else being equal, 4K would be more than double the bitrate of 1080 at the same quality level and frame rate. That works out to roughly 500 Mbps or 62.5 MB/sec. So not that bad after all, even for several streams.
I stand by my earlier point though, that Thunderbolt is not a step up for anything that already has PCIe slots. It is a huge step up for machines that never had them. Still, you’re not going to be able to hang as much outside a computer with Thunderbolt as you can hang inside a computer with PCIe slots. I’m glad Thunderbolt is opening up so much potential in iMacs and MacBooks, but I would hate for it to be the excuse for killing off Macs with PCIe slots (whatever they be called).
Best,
Andy -
[Herb Sevush] “1000 MBs Read; 831 MBs Write”
Thunderbolt has the bandwidth to support that (duplex 1250 MB/sec).
[Herb Sevush] “And even at these speeds I get the green preview line for my 5 camera multicam timelines, using ProRes 720P60.”
With your 5 stream multi cam ProRes 720p60, you are only pulling an aggregate 100 MB/sec (750Mbps aggregate), or less than 10% of the bandwidth capacity of a single Thunderbolt pipe. You’d have plenty of room left for video I/O. Plus, that 10Gb is bidirectional, so read bandwidth from your RAID does not stomp on your video out bandwidth on the same port.
Best,
Andy -
[Andrew Richards] “It’s over 3 times the frame size, for one. Like pretty much any codec, the bitrate on ProRes is relative to the quality (4×4, HQ, etc), the frame size, and the frame rate. The bitrates are not absolute.”
Frame size does not matter. It is a data rate. The data rate will not go over 330 Mb/sec (with no alpha, and unless something changes) and it usually is under that since ProRes is not CBR, but rather VBR.
720p60 = 1080i29.97. Same rate. Since ProRes is VBR and scales, the MOST any data rate will be is 330Mb/sec at 444. Anything below that, ProRes scales the data rate down. The data rates given are maximum.
4x times the frame size does not equal four time the file size when data rate stays the same. 4 times the data rate does increase the file size, though.
Jeremy
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[Jeremy Garchow] “Frame size does not matter. It is a data rate. The data rate will not go over 330 Mb/sec (with no alpha, and unless something changes) and it usually is under that since ProRes is not CBR, but rather VBR.”
Not true. Frame size absolutely matters, and there is no cap on ProRes data rates (bitrate = data rate). Apple’s own ProRes documentation lists 2K ProRes 4444 topping out at 370 Mbps, for instance.
[Jeremy Garchow] “720p60 = 1080i29.97. Same rate.”
Yes, because it is the same volume of data. 1280×720 is roughly half the pixels of 1920×1080, and 720p60 plays at double the frame rate of 1080i29.97, hence roughly the same data rate. However, look what happens if frame size is the only variable:
ProRes SD 720×486 @ 29.97 = 34 Mbps
ProRes HD 1280×720 @ 29.97 = 73 Mbps
ProRes HD 1920×1080 @ 29.97 = 147 Mbps
ProRes 2K 2048×1152 @ 29.97 = 168 MbpsThe data rate is proportional to the frame size.
[Jeremy Garchow] “ProRes is VBR and scales”
VBR permits elasticity in terms of the complexity of the image contained in a given frame, and since ProRes is an iFrame codec, there isn’t any efficiency gained by having similar frames adjacent like you get with long-GOP codecs. VBR does not mean the frame size is irrelevant to the data rate.
[Jeremy Garchow] “4x times the frame size does not equal four time the file size when data rate stays the same.”
But the data rate does not stay the same when you quadruple the frame size and keep the frame rate and quality setting the same. The data rate is relative. To quote Apple:
“The actual data rate of Apple ProRes codecs depends on the dimensions, frame rate, image complexity, and quality setting you are using.
The Apple ProRes format has a target data size for every frame, regardless of complexity, but allows frames to fall short of that target if they are simple (if they cannot benefit in quality from using more bits). Such a shortfall is not reclaimed for other frames; instead, it just produces a smaller overall file.”
Best,
Andy -
[Andrew Richards] “Not true. Frame size absolutely matters, and there is no cap on ProRes data rates”
There isn’t? I think there is. Your last quoted sentence sums it up. It does not go above, it only goes down. VBR means that every frame is not encoded at the same data rate, which is why file size very on ProRes, and it’s where it gains it’s efficiency while still being i-frame.
I was under the impression that ProRes 444 is 330 Mb/sec tops.
4 times the pixels do not equal four time the size in ProRes, there’s more math going on than that.
4k ProRes does not equal 500MB/sec.
Ok, I’m done now.
Jeremy
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[Andrew Richards] “Thunderbolt has the bandwidth to support that (duplex 1250 MB/sec).”
Thunderbolt has, but TB controllers don’t acchieve that bandwith. All tests usually max out at around 800 MB/s all chained devices in.
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“You also agree that you will not use these products for… the development, design, manufacture or production of nuclear, missiles, or chemical or biological weapons.”
iTunes End User Licence Agreement -
[Jeremy Garchow] “Ok, I’m done now.”
I don’t think so mister! Somebody spelled “optical” wrong in the subject title and I want to know who’s responsible.
Jason Jenkins
Flowmotion Media
Video production… with style!Check out my Mormon.org profile.
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[Jason Jenkins] “I don’t think so mister! Somebody spelled “optical” wrong in the subject title and I want to know who’s responsible.”
Apple! Duh.
Besides. Opitical is the new Coppier.
Fixed (for this post) and thanks.
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