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Re: [Gumstix-users] Re al Time Video Streaming
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From: Geoffrey A. <geo...@gm...> - 2011-11-02 19:22:19
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By default MPEG will give you a certain amount of latency as it waits to encode the current group of pictures (any temporal compression scheme will do this, hence the "temporal"). So depending on your settings you will always be GOP length frames behind. An MJPEG codec could be better as far as low latency goes - could turn into a bandwidth issue however. On Wed, Nov 2, 2011 at 2:50 PM, nick huang <nic...@ho...> wrote: > hi Hartz, > > Probably I am wrong and please let me know if it is the case. I found out > that some webcamera has pretty strong capability to do encoding. So by > using the "v4l2" or "libv4l2" if you want make it easy, you can actually > grab video stream at real time without consuming ARM cpu power too much. > So, what I am saying is that instead trying so hard to work with DSP etc, > maybe using a better webcamera which comes with strong encoding power is > much an easier solution. > I made a very simple demo by using "libv4l2" + SDL to grab video frame and > send to frame buffer through SDL and it achieves 30fps. Of course, in order > for highest speed, I choose the common format between camera output and SDL > display which has almost no transcoding overhead. In your case, you can > just pickup the MJPEG from camera if it supports. Then next step is just > transport the video stream directly by network. > > Anyway it is just my thought and hope it is applicable to your case, > > > > Nick Huang/Qingzhe Huang > > > > > > From: ito...@gm... > > To: gum...@li... > > Date: Wed, 2 Nov 2011 08:24:13 -0700 > > Subject: Re: [Gumstix-users] Re al Time Video Streaming > > > > > I'm actually working on a project right now that involves video > streaming. > > Nathan Young has also provided some good insight regarding video > transcoding > > on the ARM. > > > > Currently, I can get near realtime video streaming using the 2.6.34-caspa > > kernel and ffmpeg/ffserver. "Near realtime" == < 1 sec delay (probably > > around 500ms, I haven't officially measure it, however). > > > > Ffmpeg command line: ffmpeg -f video4linux2 -i /dev/video0 > > http://localhost:8090/feed1.ffm > > Ffserver setup: mjpeg stream configured at ~5-10fps, disable all other > > streams, change the feed temporary file location to /media/ram (that way > you > > don't have to write to an SDCard or Flash), resolution set down to > 320x240 > > or maybe 480x320. > > > > Make sure you max out your mpurate as all free cycles are used to encode > the > > video. > > > > If this doesn't work, try the gstreamer/DSP route. > > > > -----Original Message----- > > From: Hartz [mailto:har...@ya...] > > Sent: Wednesday, November 02, 2011 2:24 AM > > To: gum...@li... > > Subject: [Gumstix-users] Re al Time Video Streaming > > > > > > Hi everyone, > > > > I'm currently doing a project where one of the things we would like to > do is > > to operate a robot over the internet from a computer out of line of > sight. > > Therefore, it's important to have low latency video streaming to be able > to > > drive smoothly. > > > > For now, my setup is using an overo air + caspa. I have tried using > > ffserver/ffmpeg to achieve this with no success. I managed to get a video > > stream with 3-10s delay at best(LAN connection). > > > > Anyone has managed to use ffserver/ffmpeg to stream with lower latency? > Any > > suggestion on what I could try to achieve near real time video streaming > > from gumstix ? > > > > >From my further googling, I found that there's a program called > > mjpg-streamer which might be able to do the job. Anyone has any > > success/experience with it? > > > > Thanks for any help and suggestion !! > > > > -- > > View this message in context: > > http://old.nabble.com/Real-Time-Video-Streaming-tp32764344p32764344.html > > Sent from the Gumstix mailing list archive at Nabble.com. > > > > > > > ---------------------------------------------------------------------------- > > -- > > RSA® Conference 2012 > > Save $700 by Nov 18 > > Register now! > > http://p.sf.net/sfu/rsa-sfdev2dev1 > > _______________________________________________ > > gumstix-users mailing list > > gum...@li... > > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > > > > > > ------------------------------------------------------------------------------ > > RSA® Conference 2012 > > Save $700 by Nov 18 > > Register now! > > http://p.sf.net/sfu/rsa-sfdev2dev1 > > _______________________________________________ > > gumstix-users mailing list > > gum...@li... > > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > > > ------------------------------------------------------------------------------ > RSA(R) Conference 2012 > Save $700 by Nov 18 > Register now > http://p.sf.net/sfu/rsa-sfdev2dev1 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > |