Blog

The Raspberry Pi is a fantastic little computer for recording video. For about €50,- you can record in HD with full customizability and for as long as you want or have storage for. However, one issue is that the .h264 container it records in is hard to work with. It is therefore often important to convert videos to widely applicable formats like .mp4 to be able to view them properly and get the right meta information. For this I recommend the program FFmpeg.

Installing ffmpeg on a Raspberry Pi is not as simple as downloading an executable from the command line, but it is also not too difficult.

Is there a nice function to to turn something like

FirstName

to this:

First Name?

After my page is done loading. I want jQuery to nicely scroll to the bottom of the page, animating quickly, not a snap/jolt.

Is there a way to grab a video thumbnail in FFmpeg?

I'd like to grab the middle-most frame as the video and use that as the thumbnail. Video duration is unknown.

If I set TreeViewItem Background it highlights the header only. How can I highlight the whole line?

Nor JavaScript nor TypeScript has no equivalent for the language-integrated-natural-query aspect of LINQ. (hey, isn't that literally the whole acronym?)

Some of my docker containers use NFS mounts that are configured in /etc/fstab. During a reboot, I’ve seen my containers failing to start when docker engine is started before all the mount points are mounted. There is a relatively simple but not too obvious solution to this which involves tweaking systemd rules such as Requires and After.

A watchdog timer is a special kind of timer commonly found on embedded systems that is used to detect when the running software is hung up on some task. The watchdog timer is basically a countdown timer that counts from some initial value down to zero. When zero is reached, the watchdog timer understands that the system is hung up and resets it. Therefore, the running software must periodically update the watchdog timer with a new value to stop it from reaching zero and causing a reset. When the running software is locked up doing a certain task and cannot update the watchdog timer, the timer will inevitably reach zero and a reset will occur.

Luckily for us, the Broadcom BCM2835 SoC on the Raspberry Pi comes with a hardware-based watchdog timer that can do just that. You will find this specially useful if you have a Raspberry Pi in a remote location and the operating system hangs and there's no one around to reboot it.

I'm using logback in my current project.

It offers six levels of logging: TRACE DEBUG INFO WARN ERROR OFF

I'm looking for a rule of thumb to determine the log level for common activities. For instance, if a thread is locked, should the log message be set to the debug level or the info level. Or if a socket is being used, should its specific id be logged at the debug level or the trace level.

I will appreciate answers with more examples for each logging level.

I come from WPF and I don't know if it's possible to make a ListView to distribute items horizontally, with all the extras like mouse-wheel scrolling (mouse devices) and swiping (touch devices).

I've tried this, but it doesn't behave like the vertical one. Example: I cannot scroll with the mouse-wheel.

<ListView ScrollViewer.VerticalScrollBarVisibility="Disabled" 
 ScrollViewer.HorizontalScrollBarVisibility="Auto" ItemsSource="{Binding Collection}" >
    <ListView.ItemsPanel>
        <ItemsPanelTemplate>
            <StackPanel Orientation="Horizontal"></StackPanel>
        </ItemsPanelTemplate>
    </ListView.ItemsPanel>
</ListView>

A fellow emailed me earlier asking how to get the namespaces from an XML document, but he was having trouble because the XML had some XML declarations like <?foo?>.

I want to bind the background color of a button to an enum. I wonder if there is an enum object that can hold multiple values, for example the state and the color. I want to avoid two enums that could be out of sync. Here are two enums that I would like to integrate with each other.

enum StateValue { Player, Wall, Box }
enum StateColor { Colors.Red, Colors.Grey, Colors.Brown }

Then I need to create a binding for the XAML button.

<Button Content="Player" Background="{Binding Source=...?}" />

Maybe, a dictionary like the following is helpful. But still I do not know how the binding needs to be written.

public Dictionary<StateValue, Color> stateValueColor = 
new Dictionary<ElementState, Color>()
{
 { StateValue.Player, Colors.Red },
 { StateValue.Wall, Colors.Grey },
 { StateValue.Box, Colors.Brown }
};

I have a div box (called flux) with a variable amount of content inside. This divbox has overflow set to auto.

Now, what I am trying to do, is, when the use scroll to the bottom of this DIV-box, load more content into the page, I know how to do this (load the content) but I don't know how to detect when the user has scrolled to the bottom of the div tag? If I wanted to do it for the entire page, I'd take .scrollTop and subtract that from .height.

But I can't seem to do that here?

I've tried taking .scrollTop from flux, and then wrapping all the content inside a div called inner, but if I take the innerHeight of flux it returns 564px (the div is set to 500 as height) and the height of 'innner' it returns 1064, and the scrolltop, when at the bottom of the div says 564.

What can I do?

After connecting to the database, can I get the name of all the columns that were returned in my SqlDataReader?

I want to be able to find all parent types (base classes and interfaces) for a specific type.

E. g. if I have

class A : B, C { }
class B : D { }
interface C : E { }
class D { }
interface E { }

I want to see that A is B C D and E and Object

Whats the best way to do this? is there a reflection method to do this or do i need to make myself something.

By default, the Validation.ErrorTemplate in WPF is just a small red border without any ToolTip.

In Silverlight 4, the validation error is nicely styled out-of-the-box.

Here is a comparison of a validation error occuring in Silverlight 4 and WPF

Silverlight 4

WPF

Notice the really flat, boring look of the WPF version compared to the, in my opinion, great look in Silverlight.

Does any similar validation styles/templates exist in the WPF Framework or has anybody created nicely styled validation templates like the Silverlight version above? Or will I have to create them from scratch?

If anybody wants to try it out, the validation error above can be reproduced with the following code, works for both Silverlight and WPF

MainWindow/MainPage.xaml

<StackPanel Orientation="Horizontal" Margin="10" VerticalAlignment="Top">
    <TextBox Text="{Binding Path=TextProperty, 
           Mode=TwoWay, ValidatesOnExceptions=True}"/>
    <Button Content="Tab To Me..." Margin="20,0,0,0"/>
</StackPanel>

MainWindow/MainPage.xaml.cs

public MainWindow/MainPage()
{
    InitializeComponent();
    this.DataContext = this;
}

private string _textProperty;
public string TextProperty
{
    get { return _textProperty; }
    set
    {
        if (value.Length > 5)
        {
            throw new Exception("Too many characters");
        }
        _textProperty = value;
    }
}

I want to get the filename (without extension) and the extension separately.

The best solution I found so far is:

NAME=`echo "$FILE" | cut -d'.' -f1`
EXTENSION=`echo "$FILE" | cut -d'.' -f2`

This is wrong because it doesn't work if the file name contains multiple . characters. If, let's say, I have a.b.js, it will consider a and b.js, instead of a.b and js.

It can be easily done in Python with

file, ext = os.path.splitext(path)

but I'd prefer not to fire up a Python interpreter just for this, if possible.

Any better ideas?

I want all characters in a TextBlock to be displayed in uppercase

<TextBlock Name="tbAbc"
       FontSize="12"
       TextAlignment="Center"
       Text="Channel Name"
       Foreground="{DynamicResource {x:Static
          r:RibbonSkinResources.RibbonGroupLabelFontColorBrushKey}}" />

The strings are taken through Binding. I don't want to make the strings uppercase in the dictionary itself.

How can I generate a random 8 character alphanumeric string in C#?