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

[Ákos Maróy]

Andrey,

> 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

makes sense

> 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)

I see. is there a non-HTML-UI way to set these values?

> Potentially there can be several bottlenecks in the camera:
> 
> 1 - exposure time

makes sense, and obvious to understand.

> 2 - sensor limitations - for each frame dimensions, decimation and
> binning and operation mode (free running/ triggered) there is a certain
> minimal frame period.

sure, this is something beyond my control I guess

> 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.

thanks for the info. I'll try to play around with these modes. BTW, what
is JP4 mode? :)

> 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.

the camera is connected directly to my laptop, so I guess I'm doing
100mb/s. but yes, this can already be a bottleneck. (BTW, wouldn't it be
better if the camera came with a gigabit ethernet port?)

> 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.

I don't have an HDD attached.


I'll try to play around these, as soon as I can de-brick my camera (see
my latest e-mail)


Akos