[Elphel-support] how to increase the frame rate?

[Heinrich Mueller]

Am 17.11.2010 04:54, schrieb Andrey Filippov:
> On Tue, Nov 16, 2010 at 7:37 PM, Ákos Maróy <akos at maroy.hu 
> <mailto:akos at maroy.hu>> wrote:
>
>     Hi,
>
>     I wonder how to increase the framerate on an elphel camera?
>
>     When I do full resolution, mplayer seems to report a framerate of
>     10fps
>     or less:
>
>     VIDEO:  [MJPG]  0x0  0bpp  7.000 fps    0.0 kbps ( 0.0 kbyte/s)
>
>
>     but interestingly, I get the same framerate if I use half or
>     quarter of
>     the image dimensions. also, even at full resolution, the CPU load
>     on the
>     camera is actually not really high:
>
>
>
> Akos,
>
> the most likely reason (proved by the steady fps regardless of the 
> frame size) is the exposure time. Obviously the frame rate can not be 
> higher than 1/exposure time, so please check that - in the camera GUI 
> the frame rate (the rate sensor currently operates at) is shown in 
> different colors, depending on the source of the limitation.  You may 
> slightly decrease the required exposure time by increasing analog gain(s)
>
> Potentially there can be several bottlenecks in the camera:
>
> 1 - exposure time
> 2 - sensor limitations - for each frame dimensions, decimation and 
> binning and operation mode (free running/ triggered) there is a 
> certain minimal frame period.
> 3 - camera FPGA - in JPEG mode it can compress 53MPix/sec (average, 
> peak can go higher), in JP4 mode - 80MPix/sec. Sensor gets up to 
> ~75MPix sec (average) at the full frame, lower at smaller ones. So in 
> JPEG mode only with the largest frames it can be an issue, in JP4 - never.
> 4 - bandwidth of the network - up to full 10 megabytes/second over 
> 100mbps network, when you hit that limit you can try lowering the 
> compression quality with the same frame size/rate.
> 5 - similarly - HDD bandwidth, it is approximately 16MB/sec, limited 
> by the ETRAX FS CPU, improving results when lowering compression 
> quality can be an indicator. Additionally if the HDD has large 
> directory with files (best performance is achieved with simple *.mov 
> files and large limits on the file segment) there could be frame drops 
> when opening a new file segment - the camera videobuffer fro the 
> compressed frames is 19MB, so you can calculate the time that the file 
> system has to close/open file.
>
> Andrey
>
>
> _______________________________________________
> Support-list mailing list
> Support-list at support.elphel.com
> http://support.elphel.com/mailman/listinfo/support-list_support.elphel.com
@Andrey:
What are those mentioned colors like?

Heinrich
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://support.elphel.com/pipermail/support-list_support.elphel.com/attachments/20101117/5456309d/attachment-0002.html>