Am 17.11.2010 04:54, schrieb Andrey Filippov:
On Tue, Nov 16, 2010 at 7:37 PM, Ákos Maróy <[email protected]
<mailto:[email protected]>> 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
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@Andrey:
What are those mentioned colors like?
Heinrich
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