Zdenek Kabelac ([EMAIL PROTECTED]): > > It works without any external interrupt driver? What's mga_vid? :) > > Well mga_vid could be only used with Matrox card owners - which is > rather minority I would say - so it's really not a general solution > and avifile is not just MGA video player :) > > So yes it works very well even without interrupt driver with just poor > linux scheduler - but of course tearing is unvoidable in this case...
Tearing is totally avoidable without a kernel vsync device! Like I mentioned in my email, the Xv drivers for nVidia cards, i810 chips, and ATI cards all double buffer and don't flip until the next retrace! > > Yes, I am working to avoid judder at refres rates less than 85hz! > > For example, many CRT projectors can run at 72hz which is great for > > 24fps video. To ensure a 3-3-3-3 pattern we must have a vsync > > device. > > I would say we need better kernel :) Why? One with vsync devices for all video cards or one with lower scheduling latency? > Again - if you have such device - avifile will use - but if you don't > have the current solution from avifile couldn't be made better in my > eyes... (if you will enable export AVIPLAY_DEBUG=1 you will see > sync messages and you will also see how the linux scheduler behaves - > from time to time it will miss the timer wakeup point by more then > 15ms) You don't need to convince me that we need lower scheduling latencies, which is why I noted that you can do better using /dev/rtc/SCHED_FIFO. The solution sucks but it's one way to do a little better without a vsync device. > > Even worse, consider playback of 60fps material at 85hz. Judder is > > Well I do not have 60fps material :) I do use 29.97Hz movies... I'm > currious what do you mean by 60fps material - do you use some high > speed video cammeras :) in my eyes there is no such thing like 60fps > video - movie has 23.97, PAL 25, NTSC 29.97 If you deinterlace a 29.97fps NTSC stream you get 59.94fps video, each field gets expanded to a frame. > > Dude, my sentence begins with 'Given we need a vsync device'. I say > > here that we need BOTH. Don't you agree? > > Well not just 'BOTH' of us - almost every video app needs such device > :) I meant both as in we need a vsync device and all Xv drivers should double buffer. > > > odd/even frame for TV (might be used the HZ 4byte sign bit) but > > > generaly I would expect XFree driver would be doing this itself if > > > it possible... > > > > Do what itself? Tell you if you're on an odd or even field? > > No I mean - I'll give two following images and video card would be > doing proper interlacing... I'm sorry, I don't know what you mean. > > I was just suggesting. LKM gets too much traffic, and this is > > definitely a video issue. I think you'll find more interested > > people there. > > Well there is no point to disuccess this on Xpert - as long as Linus > will be mostly ignoring any improvements in scheduling (I think I do > have somewhere his sentence where he said that 1.5GHz CPU should be > fast for every video application thus we do not need to modify kernel > :) to fix latency problems Do you have a link to him saying that? A vsync device would be sufficient, and Alan Cox is apparently willing to put it in the kernel if the code is written. > I think that the need for vsync device is know for a long time and yet > there has nothing (except for my completely ignored attemp) How much did you publish your attempt? I just learned that your mga_vid had been modified. Regardless, there is interest now I think we just need to write the code. I'm currently modifying your mga_vid module to be a little more generic and I'll try to code support for i810. -- Billy Biggs [EMAIL PROTECTED] _______________________________________________ Avifile mailing list [EMAIL PROTECTED] http://prak.org/mailman/listinfo/avifile
