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Realtime performance expectations
Question about expectations: For many projects, the DV codec gives an incredible amount of realtime performance on a fast Mac, with no additional cards. Upwards of eight tracks with effects, titles, etc, all realtime.
When you upgrade to a Decklink card, so that you can work with codecs beyond DV, how much realtime do you get? Using, say, PhotoJPEG at 75%, can I still expect to get 4-6 tracks with effects before I’m forced to render? What about 10 bit SD? Or 10 bit HD?
And what happens if you add still graphics (ie TIFFs, TARGAs) to the mix.
This is all for an animatic project. System will be a G5 Quad or Mac Pro, but I’d also be interested in the same question but for a G5 dual, as this is what I have at home.
Thanks!
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3 Replies
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You’ll be delighted to read this. Real time performance increases, rather than the opposite, when you move from DV25 to uncompressed. Uncompressed codecs are much easier to decode, or so the results suggest. The only condition, obviously, is that your disk system can handle 8 or 10 streams of SD 8-10 bit UC footage at 20-26 MB/s. Just stripping a couple of SATA drives won’t give you that kind of disk performance (but it will allow you to work with that kind of quality for very little money, if at some point it’s more about quality than performance).
RT performance with uncompressed HD is nowhere near these numbers. In fact, if it was, it would be impossible for most people to afford the kind of disk system needed for that. Bear in mind a single, 10 bit UC stream is about 140 MB/s. Can you imagine what kind of RAID is needed for playing back 4 or 5 (not to mention 8) of those simultaneously?
DVCPRO HD does work very well in RT.DV25, ie regular plain DV/DVCAM/DVCPRO gets a performance boost also, since the Decklink cards have hardware support for DV playback that it seems the CPU benefits when not having to deal with the Firewire DV output thing.
PhotoJPEG, last time I checked, wasn’t enabled in FCP for real time playback at all. In fact, the RT menu doesn’t show the different Safe/Unsafe RT submodes it shows for evertything else. It’s still a great codec for many things. Just not for RT effects editing.
DV50 is somewhat more demanding than DV25, but it’s so much better and the data rates are very reasonable. And RT performance is as good as you could ever need, given that if you’re doing complex layered compositing you would better be using in a specialized application, right? All around a good codec to work with things like Betacam SP and even near Digibeta quality with a single, independent SATA drive.
Still graphics… they play in real time in normal quality, and the keying for alpha is also RT. Large photos scaled down, look better when you render them. There’s a very high quality setting for spatial transformations with improved motion filtering that only kicks in when you select it in settings and only when you render the segment. Otherwise image quality and performance is very good based on the standard for NLE software, not compositing or motion graphics software.
Adolfo Rozenfeld
Buenos Aires – Argentina
https://www.adolforozenfeld.com
adolfo(AT)adolforozenfeld.com -
How about in XP? Is there much of a difference?
Brett
Brett Howe
Creative Director / Producer
Brave Vision Pty Ltd -
While RT can be improved by using uncompressed standard definition codecs and hardware from companies like Blackmagic you should be aware that there is also a down side. This is latency. When working with DV25 most people are just viewing on their computer display. When working with hardware driving an external monitor you are pushing 2 very different displays at the same time which can cause lag. If you add RT to that you can have situations where there can be a delay of a second or more before playback can start, or even a still of your current composite can be displayed- the beach ball just spins. This happens most often with unlimited RT so I usually run in the safe setting. Setting external monitoring in FCP to single frame or turning it off completey should help but does not. Just wanted to let you know so it isn’t an unpleasant surprise.
BTW, I am not putting down the idea of uncompressed and external hardware- the quality is vastly better and you can see what the output really is, instead of an approximation. I just wish there were a way to make editing on FCP as responsive as it is on an AVID.
Chris Paul
POV
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