Hi Michael and all, I have been asking the question whether BT8x8 cards write video data directly on to the framebuffer many times. But I got the answer from your mail. If BT8x8 cards write video data directly on to the framebuffer, how can we read the video data from "/dev/fb0" instead of "/dev/video0" ? I am using Microwindows (www.microwindows.org) to develop a tv viewer application like "Xawtv" which uses "/dev/video0" to read video streams. I have planned to develop a tv viewer application which reads the data from "/dev/fb0". On Mon, 2003-12-29 at 22:07, Michael Hunold wrote: > Hello Leonid,. > > > is there way to "catch" vertical frame (field) synchronization > > using BT8x8 cards and bttv driver ? > > You have to distinguish between the synchronisation of your image source > (ie. the bt8x8 card) and the synchronisation of your output (ie. your > graphics adapter). > > In overlay mode (ie. when the bt8x8 is writing directly to your > framebuffer) there is nearly no way that you can synchronize these two, > especially if you're using a TFT. While the video is incoming with 25 > frames (or 50 fields) per seconds, the TFT is usally displaying it's > picture with 60 frames per seconds. > > In grabbing mode (ie. when the bt8x8 writes the picture to some > offscreen memory), the synchronisation of your incoming picture is not > important. > > What you really need is a way to synchronise the output, ie. a way to > tell your output device: "wait for the next vertical sync, then flip to > the next frame, so I don't get any tearing effects". > > I don't know if X finally has something (ie. a "X vsync extension") like > this, otherwise you need to use some other toolkit like DirectFB > (http:/www.directfb.org) that lets you sync your output to the vsync. > > > Regards, > > Leo. > > CU > Michael. > > > -- > video4linux-list mailing list > Unsubscribe mailto:video4linux-list-request@xxxxxxxxxx?subject=unsubscribe > https://www.redhat.com/mailman/listinfo/video4linux-list -- S.Suriya Mohan, MCA. Software Engineer, Insys Technologies, Coimbatore-641001. India. There is no substitution for hard work.
