Sunday, September 29, 2013

Android emulator temporary directory

Wondering where your disk space goes when using the Android emulator?   Apparently it goes inside /tmp/android-$USER (where $USER is the current user logged in):

Saturday, September 28, 2013

Experimenting with a HDMI to VGA converter....

Recently I bought an HDMI to VGA converter in an attempt to feed the output from a laptop to an older LCD projector. When trying to test this converter with a Thinkpad T510 laptop and 25" HP monitor, I noticed that there was no video signal detected.   I tried another Toshiba laptop but could get no signal from the monitor.  At first I thought that this device was defective and need to be returned.

However, after feeding the HDMI signal from the laptop to an HDMI splitter and connecting one of the HDMI outputs with this converter, I could start to see a video signal.    Apparently the HDMI to VGA converter draws power from pin 18 of the HDMI connector, which provides the 5 volt power supply.  The HDMI specs specify that source devices should provide a minimum of 55 mA, but the chipset used by the HDMI to VGA converter must be drawing much more than current than what can be provided by the laptop.

Even more interesting, the video signal could be detected with a 25 foot MediaBridge cable but not with a 25 foot Aurum cable.  The major difference?  The former uses 28 AWG gauge wiring, while the latter uses 30 AWG gauge wiring.

Why does the gauge of the wiring matter?   With the lower gauge wiring, the diameter is usually larger, so the resistance is lower and therefore the current is higher.   Even when using the HDMI splitter that will provide additional power, this current can be reduced by the longer cabling.

The solution seems to be to use an active HDMI to VGA converter, since sufficient current draw is mentioned as a possible issue by the active converter devices sold on Amazon.   However, after this finding, you may also need to consider what HDMI cabling you're using too!

Playing 720p and 1080p videos on Ubuntu 12.04

If you find the playback for MP4 files saved to 720p or 1080p resolution on Ubuntu 12.04 choppy and you're using an Nvidia graphics card, you might want to try using the proprietary Nvidia drivers and make sure to install the VDPAU library installed.

The stock Movie Player does not appear to support the hardware acceleration capabilities, nor does the VLC version v2.0 that comes with 12.04.  You'll need to install VLC 2.2 from the repo.

VLC 2.2 upgrade installations are here:

You can also force MPlayer from the command-line to always use the VDPAU extensions:

Sunday, September 15, 2013

Android x86 on Ubuntu

Apparently using the Android virtual emulator is a bit slow on x86 machines, so the recommendation is to use the Android x86 versions.

The images can be downloaded from here:

The instructions are here:

Though the Android SDK has instructions for downloading this image directly: