The N900 records video in the 800 x 480 resolution and is one of the few Nokia devices to be able to focus before starting to capture video. But if the position of the subject changes, the N900 is not able to keep up as the focus remains fixed once the video capture has started. This however is about to change.
m2cm2c has put together a python script using v4l2-ctl that allows you to change the focus during capture. It adds two buttons to the status bar that allow you to manipulate the focus either with the on-screen buttons or switch to the keyboard and control focus with the zoom keys. I’ve put together a small demo of how this works.
- In order to get started you will need to download the script, which is packaged as .deb file so that you can install it like a normal application. Get the latest version from here. I’ve also uploaded the current version (as on 06 May 2010) to our server so that you can download directly.
- Once you have downloaded the file, transfer it to the N900, locate it via the File Manager and tap on it to begin installation.
- Once installed, you will see the two icons shown below in your status bar when the camera cover is open. The camera app launches in the full screen mode so to see the status bar, tap a blank space on the screen. Then tap the date/signal/battery cluster to bring up the following menu.
- A green indicator means that the keyboard shortcuts are turned off. Tap on it to switch them on.
- Red means that they are engaged. In this mode the auto focus at the start of the video will be disabled and you will be able to manually focus with the zoom keys and begin shooting the video. During the video you can continue to change focus with the same keys.
- In case you do not wish to enable the keyboard shortcuts and keep the auto focus at the beginning of the video, start shooting as you would. Tap the status bar to bring up the menu, choose the icon next to the keyboard and the following screen will pop up during the video capture. Now use the bar to change focus. You can drag to change focus quickly or tap toward the left or right for a smooth focus effect.
In my experience I have found that it is best to disable the keyboard shortcuts at first, start shooting and then enable them if required at a later stage. This way you get zoom key control for focus as well as the ability to auto-focus in the beginning. This script also allows you to turn on the LEDs for video light assistance and turn off the annoying red light during video capture. Look out for a separate post on this functionality later today.
With this hack the N900 is now one of the more advanced video capture mobiles around. Awesome work from m2cm2c.