Clifford Chambers – new site containing photographs from the past

May 28

adminMiscellaneous Comments Off

Clifford Chambers the village where I grew up, now has a site cataloging pictures from the past century.

mogrify – convert the existing image with imagemagick

May 08

adminLinux General, Useful Utilities Comments Off

Thanks to Rory McCann for pointing this one out.

It is possible to convert (resize, rotate etc) an image without creating a new file. mogrify takes the same options as convert but operates on the existing image. Both are tools included in imagemagick.

Asterisk-oh323, GnuGK with VPoint-HD

May 04

adminLinux System Administration Comments Off

A warning to all: audio does not work full-duplex when calling from a VPoint (VCON Emblaze) H323 client -> GNUGK -> Asterisk-oh323 -> SIP client. Tested with versions 8 and 10.

However audio works perfectly in the other direction.

The solution would appear to be to use OOH323. However the audio is again half duplex in the scenario where SIP clients are calling H323 clients.
Therefore calls originating from Asterisk to H323 clients use the ‘OH323′ module, and calls from GNUGK into Asterisk use the ‘OOH323′ module.

Linux CPU Scaling Governor – Performance and Overheating

May 01

adminLinux General Comments Off

On my previous laptop I suffered with repeated over-heating problems whenever CPU load went high for a prolonged period. After several emergency shutdowns (performed by ACPI) I discovered the problem:

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

returned the result: “performance”

Inserting the following line before the ‘exit’ line in /etc/rc.local:

echo "conservative" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

resolved the problem.

For all available scaling governors:

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors