[Elphel-support] datarate issue - HDD recording, while streaming.

[Andrey Filippov]

Sebastian, nice job!

You may try to adjust coring value - that will allow you to change file size
more gradually than in 1% increments.

Andrey

On Mon, Oct 17, 2011 at 1:14 PM, Sebastian Pichelhofer <
sebastian.pichelhofer at gmail.com> wrote:

> I ran a full measurement cycle.
>
> With and without streamer enabled, I also reduced the AJAX call
> frequency in camogmgui to once every 5 seconds to not give PHP an
> additional CPU load in the camera. All values are averaged over 5
> seconds.
>
> JPEG Quality and data-rate are relative not absolute as the data-rate
> depends on the actual image content but I kept it as reference during
> the tests.
>
> All tests were done with 1920x1088 at 25fps RGB Color mode.
>
> Regards Sebastian
>
> On Mon, Oct 17, 2011 at 18:12, Oleg K Dzhimiev <oleg at elphel.com> wrote:
> > Nathan,
> > I was able to reduce the PHP's cpu usage and could run recording
> > 1920x1088 at 25fps, quality 93, with streamer working, single frame size
> > ~300K-~400K,
> > streamer ~60% cpu, camogm ~30% cpu (same w/o streamer).
> > The problem is that the php calls (status requests) are "too frequent" so
> > that they eat ~30%. I used my own interface (originally for our panorama
> > camera) for recording where the status calls interval can be programmed.
> > So that interval was 5 sec - can be more frequent, 2 sec worked also.
> > It could be a solution if Sebastian implements it in his GUI.
> > Regards,
> > Oleg
> >
> > On 11 October 2011 22:24, Nathan Clark <nathan at nathanclark.com.au>
> wrote:
> >>
> >> Forwarding a short discussion regarding datarate limitations recording
> to
> >> HDD while running streamer simultaneously. Continuing discussion here so
> >> that others may benefit.
> >> Problem:
> >> Cannot record to HDD with high datarates when streamer is running.
> >> Cause:
> >> Streamer running with high datarate results in high CPU usage causing
> >> bottleneck.
> >> Fix:
> >> • Reduce CPU requirements of webserver
> >> • Reduce CPU requirements of streamer
> >> Is it possible to have the streamer skip every n frames?
> >> This would potentially halve the datarate (if skipping every 2nd frame)
> >> and as such significantly lower the cpu requirement.
> >> The reduced temporal resolution of the stream would still be okay for
> >> viewing in many circumstances.
> >> Oleg,
> >> • I get a similar cpu% usage for php instances.
> >> • I do need the use of the streamer, while recording to SSD over sata.
> >>
> >> Cheers,
> >> Nathan
> >> ---------- Forwarded message ----------
> >> From: Oleg K Dzhimiev
> >>
> >> Also, can we move the discussion to our mailing list.
> >> Thanks
> >> On 11 October 2011 12:41, Oleg K Dzhimiev wrote:
> >>>
> >>> Nathan,
> >>> What's the CPU usage for php while recording? I got ~(24+27)% from two
> >>> php instances. That might be causing the problem - too many php calls
> from
> >>> the GUI.
> >>> In your application do you use the streamer while recording?
> >>> Best regards,
> >>> Oleg
> >>>
> >>> On 11 October 2011 05:55, Nathan Clark wrote:
> >>>>
> >>>> As Sebastian advised, I tested the CPU with streamer enabled...
> >>>> We have a problem!
> >>>>
> >>>> CPU usage for streamer is up at 67%
> >>>> (at 1920x1088, rgb, 25fps, quality 90 - data rate 6.9MB/s)
> >>>>
> >>>> The CPU usage directly correlates with data rate, reducing quality to
> 20
> >>>> (0.86MB/s) results in streamer CPU usage between 3-9%
> >>>>
> >>>> It looks like the streamer is causing this recording issue by
> >>>> bottlenecking the CPU and thus causing the buffer to overrun...
> >>>>
> >>>> But how to circumvent this issue?
> >>>>
> >>>>
> >>>> On 11/10/2011, at 21:23, Sebastian Pichelhofer wrote:
> >>>>
> >>>> > Hi Oleg, I suggested we continue this discussion via email.
> >>>> >
> >>>> > Below is Nathans original PM to me:
> >>>> >
> >>>> >
> >>>> >
> >>>> > Hey Sebastian,
> >>>> >
> >>>> > As time escapes me, its getting closer and closer to Winnie shooting
> >>>> > her experimental film for her stereoscopic PHD research...
> >>>> > I am not ready :|
> >>>> >
> >>>> > With problems with my lenses and this sata datarate pain, it's
> >>>> > becoming quite scary :shock:
> >>>> >
> >>>> > But there is always times of stress with all projects! And
> ultimately,
> >>>> > I just remind myself how amazing what we have created really is! :D
> >>>> >
> >>>> > ----------------
> >>>> >
> >>>> > Did you have time to verify the external HDD recording datarate
> limits
> >>>> > we talked about some time ago?
> >>>> >
> >>>> > Regards Sebastian
> >>>>
> >>
> >> _______________________________________________
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> >>
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> >>
> >
> >
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> >
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> >
> >
>
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