[Elphel-support] Elphel performance, Framerate / JP4

[Andrey Filippov]

On Sun, May 23, 2010 at 3:03 PM, Andreas Bean <office at beanbox.com> wrote:

> Hello Andrey,
>
> I measured the writing speed with dd. The result is 8.6Mb/s which agrees
> with the experienced recording limit in camogm.
> Why is the value so low? The cam came with the hdd preconfigured.
>

Andreas,

I would try to attach some external  SATA HDD and measure the speed - in
that case we'll be able to find if the problem is with the camera/software
or with the HDD.


> Where can I find more information on setting the gain of the second green

select "autocamparsms.php", check parameters related to white balance

Then I would try "WB_SCALE_GB". Or turn the white balance off and edit all
the gains manually (GAINR, GAING, GAINB and GAINGB). You can select multiple
parameters you need to change on one page, combining them in
parsedit.php?... url string.


> and howto decode the jp4-hdr data?
>

There is no manual how to do that, you have to collect information from the
several places.
1) article in the LinuxDevices and the demo page I linked earlier
2) source code of the driver that creates frame headers - I tried to put
sufficient comments with the code -
http://elphel.cvs.sourceforge.net/viewvc/elphel/elphel353-8.0/os/linux-2.6-tag--devboard-R2_10-4/arch/cris/arch-v32/drivers/elphel/jpeghead.c?revision=1.1.1.1&view=markup
3) Ask Paulo

Whats the best way to contact Paulo?
>
He is in the CC of my previous message, I also believe he is subscribed to
this list.

>
> Have you ever considered connecting the hdd directly to the fpga?
>
No, I did not. hardware implementation of the ATA is definitely possible,
but I'd rather leave it to the CPU/SOC manufacturers, otherwise it may add
several hundred dollars to the cost of each Elphel camera

> Is the data throughput better in the new 373 board?
>

Yes, sure - it has faster processor and there is no UDMA bug as there is in
Axis ETRAX FS processor.

Andrey
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