From: <ssc...@wo...> - 2005-08-05 12:34:25
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Chris, I'm totally with you on this one. the short answer: you'll never get full motion video recordings from Motion the long answer: Last year, I think in the fall, I did something similar, except my hardware wasn't as extensive as yours, but neither was my requirements... You can probably search out my thread in the archive. The explanations I received were essentially this.. or at least how I interpreted them. Because motion is watching for "motion" in the video, there is a serialization to the process, especially when you add in the compression. I initially understood this to mean, stop recording captured frames in JPEG and have motion store them in PPM, where later I would compress them offline. The result was "less" frames captured, and in addition, I found out through this process that motion doesn't work with RGB 24 data, but reduces the signal down to some 16 bit... either through the data type it requests from the capture device, or manually converts before analyzing the video if the card doesn't support the requested data type, which explains why I never thought the motion captures had the same color richness as some other capture schemes. Don't get me wrong, I'm not bashing motion, rather the problem is our trying to use motion for something it wasn't written for. I haven't had a lot of time to try out other schemes, but my next attempt is going to use motion to watch the video, and have it kick off "streamer" to record for a predetermined amount of time from a secondary port, to where the video signal has been duplicated. "streamer" is part of xawtv, and I've successfully recorded full motion video (without any kind of external motion detection), supposedly it will record audio as well, but I don't have a decent audio source to try with. http://linux.bytesex.org/xawtv/ to be clear "streamer" is a recording application, it doesn't have any logic to do what Motion does The only other scheme I can think of is to use Zoneminder, which the author answered my query, that zoneminder works with RGB24, and it can create PPM files that are RGB24... but I haven't tried it, so I don't know if there are caveats, nor do I have any idea what the throughput rate will be for it. The documentation I read on zoneminder's website suggested he had received a fair amount of requests to include audio recording on recorded events, but it looks unlikely he will put the effort into writing it, but it's been a while since I read the documentation. ----- Original Message ----- From: Chris Coulthurst <ch...@sh...> Date: Friday, August 5, 2005 4:41 am Subject: [Motion-user] Disk writes vs bus speeds vs framerates on LMLBT44 (brooktree878) PCI woes - advice? > > I recently built a Dual P3/700 coppermine machine with a Mylex > Dac960 Raid > 5, a single 60gb UDMA100 IDE spare disk, a gig of ram, and through > a fully > compiled gentoo on it. This machine is about as fast and > efficient as I > know how to make it. > > I throw a LMLBT44 card (8 BNCs at 30fps, although Im only using 4, > and the > board has 4 chips on it not just one) on the system, do a little > kernelcompiling, and module installing, and everything is found, > detected,working, tested with xawtv and the like. Cherry. > > I installed ffmpeg 0.4.8 (for the mpeg1-ness) and the lasted > motion, and > configured it for a single /dev/video0 test to get started, > writing 320x200 > jpegs and mpeg1 stream to the U160 SCSI mounted with ext3. I've tried > varying framerates. > > I'm familiar enough with the woes of the 'video moves too fast' > issues, and > require a bit more information if I may: > > The most contiguously written frames that I could get on ONE > channel was 7 > (watching the timestamp decimal rollover on the filenames). This > was at > 640x480, 75% jpeg compression, and NOT recording ffmpeg movie. > Whats odd to > me is, when I tried the same thing with TWO video sources from > threadx.conf,the most I could get per channel was still 7. > Doubling the workload didn't > seem to cut in half the consistent framerate. > > I am trying to find where transfer bottlenecks are, to see if some > of them > can't be lessened or eliminated. I want to optimize disk > transfers, using > the best filesystems with the best block-sizes, not worrying about > efficientstorage-capacity, just THROUGHPUT to the block device. > Which reminds me, if > anyone knows proper compile flags to optimize Motion, I'd > appreciate it, > since I didn't emerge it, I rolled my own tarball. > > Are there ways to speed up, or prioritize the pci bus to the SCSI raid > array? (I've heard of such things in my dealings with the Asterisk PBX > project to eliminate analog voice latency issues). > > Which FS should I probably use for fast file writing? What is a > good block > size to use if my files are ~16K each on jpegs? > > Its important to me that I get as near-full-motion video as > possible, even > if this means not compressing the video until a night-time non- > activity when > the server gets some breathing room to do so. > > Any advice as to where these bottlenecks might be improved would be > appreciated. Some may say I'm being futile in trying to do all > this with a > non-mpeg-compressing card like the LMLBT44, but my logic was to be > able to > dump raw images in order to have more flexible manipulation with > the final > media. Since a few cameras might be at some distance from the > "intruder",more individual high-quality jpeg frames are more > important to me than > having a movie file written on-the-fly. I'm almost thinking I > should have > one of each, with two feeds off the same camera to accomplish both. > > Thanks for listening if you read this novel! > P.S. I have precapture off, so you know that. Any help on anything > abovewill get you invited to Christmas dinner! > > Chris Coulthurst > ch...@sh... > > > > ------------------------------------------------------- > SF.Net email is Sponsored by the Better Software Conference & EXPO > September 19-22, 2005 * San Francisco, CA * Development Lifecycle > PracticesAgile & Plan-Driven Development * Managing Projects & > Teams * Testing & QA > Security * Process Improvement & Measurement * > http://www.sqe.com/bsce5sf_____________________________________________ __ > Motion-user mailing list > Mot...@li... > https://lists.sourceforge.net/lists/listinfo/motion-user > http://www.lavrsen.dk/twiki/bin/view/Motion/WebHome > |