Thread: [HOWTO]Watch 720p videos on n900 [09.12.2011 VIDEOCALL WORKS]
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maacruz is offline maacruz
2012-01-12 , 22:35
Posts: 1,101 | Thanked: 1,185 times | Joined on Aug 2008 @ Spain
#823
Originally Posted by freemangordon View Post
only a sink, my main idea adding xoverlay support was to offload CPU while recording video, hopefully reducing stutter in recorded video. While using omapfb as preview sink loads CPU only 20%-30% @250MHz (1280x720@30fps) there is still some stuttering. Seems the roots of dropped frames in videos recorded with n900 camera are not in CPU load. Yet to find the real cause.
The timer is the cause. The number of task switches is bounded by the timer, and the N900 is at 128 Hz. It happened in my computer, the default kernel is compiled with a 100 Hz timer, and while it has cpu enough for real time xvid capture it stuttered. Once I changed the timer to 1000Hz, even with high cpu load it doesn't stutter.
Try building a kernel with CONFIG_HZ=256 and CONFIG_OMAP_32K_TIMER_HZ=256, or even 512 (my DT kernels for the N810 are at 256 with no ill effects at all, and the N810 has a much slower cpu)
 

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