Thanks Douglas, That's a good point. I'm playing a dozen or more videos all at the same time, so it's a tricky balance between decompression rates and file size.
I'll post my situation in QT-dev too. Cheers, t On 2010-01-15, at 11:55 AM, douglas welton wrote: > Travis, > > I suspect that your issue might be related to compression. To achieve a > smaller size takes time. Decompressing a video frame can take longer than > you have to display it. Try compressing your video with the Animation codec > as opposed to the H.264 codec. File size will balloon, but decompression > time will go down and perhaps facilitate your playback. > > If you want to know more about which video compression to use, I would > suggest that you take this discussion to either the QT-dev or QT-users list. > Those folks are the subject experts. > > later, > > douglas > > On Jan 15, 2010, at 12:29 PM, Travis Kirton wrote: > >> Hey Jean-Daniel, >> >> Thanks for the advice. We've already noticed that the main object that's >> taking up the most CPU seems to be whichever decoder we're using >> (jpegdecompress... etc). I haven't looked into it thoroughly enough yet, but >> hope that using GCD to distribute blocks of code across the 8 cores we're >> running. >> >> I'm not really versed enough to know whether one codec is better than >> another for what we're doing, even though it seems that using movies >> compressed with Apple Video is lighter on the CPU than even H.264... >> >> T >> >> On 2010-01-15, at 12:47 AM, Jean-Daniel Dupas wrote: >> >>> >>> Le 14 janv. 2010 à 20:11, Travis Kirton a écrit : >>> >>>> Hi, >>>> >>>> We're working with Core Video to play back videos @ 1024 x 768 resolution. >>>> The videos are stacked on top of one another and revealed as a user draws >>>> over top of them. To achieve this "drawing into" the stack of videos, >>>> we're filtering using CIImage to create alpha masks over top of an >>>> individual video. >>>> >>>> Playback is very choppy, and we haven't been able to determine if it's the >>>> compression we're using (i.e. the video assets themselves) or anything to >>>> do with the combination of Core Video, Core Image & the 1024x768 format. >>>> >>>> Some problems we're facing is that even if we're only using 2 videos and >>>> not doing any filtering, the videos lag. >>>> >>>> We initially we compressed our original files out, so that the overall >>>> file size is much smaller. Even still, with 2 movies @ approx. 50MB each >>>> we're having problems. >>>> >>>> Using TOP, from terminal, to overall system usage we're getting results >>>> that the system is chewing up to 180% cpu. >>>> >>>> We'd be really greatful for any help on whether this is an asset, a code, >>>> or a compression issue (or all three). >>>> >>>> Cheers, >>> >>> Ask Instruments, it is the only one able to tell you what's going on. >>> The simplest way to do this is to use the Xcode Menu Run > Run with >>> Performance Tool > Time Profiler. >>> >>> >>> -- Jean-Daniel >>> >>> >>> >>> >> >> _______________________________________________ >> >> Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) >> >> Please do not post admin requests or moderator comments to the list. >> Contact the moderators at cocoa-dev-admins(at)lists.apple.com >> >> Help/Unsubscribe/Update your Subscription: >> http://lists.apple.com/mailman/options/cocoa-dev/douglas_welton%40earthlink.net >> >> This email sent to douglas_wel...@earthlink.net > _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
