[Elphel-support] Recording fullHD JP4 being limited to 7 seconds

[flavio soares]

Hello, everyone,

Yesterday I took my time to read many posts of this support list. It's
quite nice to see how active it is, so congratulations. I'll see if I
can go deeper into camogm's documentation, because it really
interested me.

I am conducting some recording tests here, both to check whether my CF
cards are working fine and to see how far I'd be able to get with
them. They announce they have a recording speed of 20MB/s, which in
theory should suffice my needs, but let's put them to the beat. =)

So, the reason I write is that, during these tests I noticed something
odd. When recording full HD JP4, the files are being stopped when they
reach 7 seconds (or, better saying, the file is closed and recording
continues in a new file). I've changed the settings to guarentee the
"split size" to be of almost 1GB, and the "splt length" to be of 120
seconds. It may be that these 7 seconds are when the buffer reaches
its full cycle - however, whenever this happens, camogmgui sends a
warning notice, which does not happen.

There is an image annexed, but in case this list may not accept
annexes, the "Data Rate" of the recording is of 7 MB/s. The framerate
that is showing there is of "30.875", but I've fixed them to 24 FPS in
camvc to have a safe margin. Compression was set at JPEG Quality 80%.

I've tried lowering the resolution to 640x480 (keeping JP4 etc) and
the recording goes fine - even after the buffer recycles. The
recording went over 40 seconds, without any apparent fault. This
file's size is now over 170 MB also. This makes me sure the problem
with the full HD JP4 is not of file size.

If I turn the resolution up to full sensor size, 2592x1936, the
recording seems to limit to 3 seconds per file. Recording data rate
reaches 8 MB/s.

Can this be due to my CF cards speed? Does this happen when using external HDs?

ps.: I thinking of conducting the same tests with an external SATA HD.
Is it safe for me to plug the data cable at the back of Elphel and
connect its power cable to my computer, just for testing?

Thanks!

flavio
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