Lab Notes: Compiling ffmpeg for WebOS

It is a dream of many to have VLC running on WebOS.  I thought that with the release of the PDK, I would start exploring this.  Since VLC uses many of the codecs provided by ffmpeg’s libavcodec library, it made sense to start by compiling this library and verifying basic functionality.

In the end, I got ffplay to play a video on WebOS using libavcodec, the result was anti-climactic for large videos due to the lack of HW acceleration, one of the Palm PDK guys, unwiredBen provided information for further research.  Overall, performance for smaller files is acceptable, and the ability to grab rtsp streams could lead to many applications.  The lab notes are below.

Collision Detection for WebOS SDL/PDK

Collision Detection

Yoda trains Luke in the ways of the PDK.

An SDL padawan you are.

Drawn images to the screen using SDL_BlitSurface you have.

How to detect button presses you know not!

mMMmm, much to learn you still have!

Collision detection isn’t just for video games!  Imagine, your finger colliding with an image and then something epic happening.  This post is going to explore a simple way to detect when things collide.

Input & The Event Loop for WebOS SDL/PDK

Reading Keyboard & Touch Events

SDL provides everything we need to read keyboard input and screen taps.  There is only 1 new data type that hasn’t been covered previously, SDL_Event, the SDL wiki says it best:

The SDL_Event union is the core to all event handling in SDL; it’s probably the most important structure after SDL_Surface.

What we are about to do here is lay down the skeleton for event processing, the loop that keeps the app running, responds to input and displays output.  If you have an engineering background in feedback and control systems, we are about to define our transfer functions.  SDL_Event is a key player here since it allows us to get keyboard and tap events.

Drawing Images for WebOS SDL/PDK

Drawing Images

Half of making a game is drawing the images to the screen, it’s not too late to enter into the PDK contest folks!  Thankfully, drawing an image is simple with the functions provided by SDL_image.h.

Displaying an image centered in the screen

Barebones SDL For WebOS PDK

This article covers creating barebones SDL apps for the WebOS PDK.  The following topics are covered:

• How to write a minimalist SDL app
• How to set screen resolution based on device

The 10-minute guide to Ares for WebOS

This is the 10-minute reference that I was looking for when I started using Ares for my WebOS projects.  Topics covered:

• UI Basics
• Widget Fundamentals
• Using Widgets the Ares Way

Using Regular Expressions to parse XML

My first Android project was a dashboard status widget for World of Warcraft servers.

WoW Status Widget

I’ve done my share of XML reader coding in .NET and I wasn’t thrilled about using the XMLReader Java class.  In my experience, the methods for parsing an XML structure are not simple or elegant, it always feels like too much code to  arrive at the data you want. I love XML for what it is, it’s great for serializing classes (if those classes are under your control) but I hate working with it from a parsing perspective.  If your experience is different, please enlighten me!