Modern developments have to remain compatible with the existing technology in some aspects, and for that reason, even if progressive signals (as well as modern displays) don't require the V-Sync pulse, it still needs to work as if the V-Sync pulse is there.
Because of that, game developers usually make use of the vertical blank interval to increase the framerate by disabling V-Sync. This allows developers to adjust the content of the framebuffer during these dead times.
As a result of turning off V-Sync, a new problem arises and that is a visual artifact in which a previously drawn frame overlaps the next one (because of the lack of synchronization), causing what is known as page tearing, because the entire picture looks like it is cut in half; the upper half containing the previous frame and the lower half the new one.
You may have experienced this problem firsthand in many recent Xbox 360 games. Perhaps you've pondered if there is a problem with your video setup or if there is a solution. We decided to go straight to the technical gurus within Microsoft for the answers.
Chris Satchell, GM of the Game Developer Group at Microsoft took a moment to answer our queries and help us understand why gamers are experiencing page tearing in a handful of Xbox 360 titles. Will this be a long term issue and something we'll see in future Xbox 360 titles? Find out what Chris had to say...
* TeamXbox: Many users have witnessed what is known as "page tearing" when playing a few Xbox 360 games, blaming a lack of vertical synchronization in those games as the cause of this visual artifact. Is it actually the lack of V-Sync as the reason for "the page tearing" seen on some Xbox 360 games, or could it be a problem with the output resolution and the user's display? Essentially we want to know exactly what is causing this visual anomaly.
* Chris Satchell: Users are correct; "Page tearing" is an artifact of changing the displayed frame of the game while the display device is partially through displaying the previous frame. Games normally choose to wait for the v-sync signal from the console to know that it is safe to swap to the new game frame in a way that will not be perceived by users. Often there is some dead-time while waiting for the v-sync signal; a buffer to make sure the game always is ready at the right time. Some games choose to cut the timing extremely tight to get more into each game frame and if for any reason a frame is not ready for the v-sync they change the frame anyway. This can result in a visual tear, but means the game-play remains smooth with no jitters. Other games decide to run a maximum consistent frame-rate that does not match exactly to the v-sync patterns this can result in higher fidelity control, but with occasional tearing (the vast majority of frames are absolutely fine).