From the monthly archives: January 2012

Slice Resynchronization in MPEG4

By On January 30, 2012 · Leave a Comment

MPEG4 Part-2 introduced three error resilience tools, including Resynchronization, Data Partitioning and Reversible VLC. This post discusses Resynchronization only.

The Problem

The bitstream of a MPEG4 video frame (and lots of other video codecs) is encoded using VLC (Variable Length Coding). Because the number of bits for each coefficient varies and the length is [...]

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TCP TIME_WAIT State and Address Already in Use Error

By On January 25, 2012 · Leave a Comment

0. The Problem
Recently I am working on a project consists of TCP socket programming on Linux. I encountered errno 98 (address already in use) and 99 (cannot assign requested address) frequently. I wrote a small test program to reproduce the issue. The test code is as below,

#include <stdio.h>

#include <stdlib.h>

[...]

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Video Converter Android Has > 50,000 Downloads

By On January 25, 2012 · 1 Comment

Video converter android has reached 50,000 downloads on Jan 21 2012. It reaches this number in slightly more than one month.

Though it’s still in beta release with lots of issues and not so good reviews (~3.0), the download figure makes me believe it’s an app that people need. The app is even listed [...]

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Android Custom Notification with Progress Bar

By On January 20, 2012 · 3 Comments

When your android app is doing something that user needs to wait, it’s better to tell the user how much has been done and how long user needs to wait. Progress bar comes into handy. Sometimes user goes to other app, but still wants to check out the task your app is doing, then a [...]

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Frequent Custom Status Bar Notification is Evil on Android

By On January 19, 2012 · 1 Comment

The Story Behind

In my recent app, video converter for Android, I add a notification progress report on the status bar. So users can view the video conversion progress any time. I also did several other changes, and then start running the final test before release.

Then I found the [...]

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Power Tutor–Android App Measures Power Consumption of App

By On January 19, 2012 · 4 Comments

Mobile computing and smart phones cannot be what we see today without powerful and energy efficient batteries. Mobile application developers, however, don’t get used to think of building energy efficient apps. Sometimes, it can affect the application a lot.

I recently found a tool, Power Tutor, that runs on Android devices to measure the power [...]

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Use memset to Avoid Loops in C

By On January 13, 2012 · Leave a Comment

The Usage of memset

memset has the following definition,

void* memset(void* s, int c, size_t n);

The method set each of the first n bytes of memory pointed by s to c and return s. Note that although the second parameter has type of int, it’s converted to unsigned char before the memory operation [...]

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How to Associate Process with Port Number using lsof — in Linux and Android

By On January 12, 2012 · Leave a Comment

Sometimes it’s good to know port numbers used by certain processes. For developers, we can use this information to do application based packet filtering, network statistics detailed for each app, etc. For admins, we can use it to diagnose the network, detect malware etc.

Unfortunately, there’s no direct API or tools that provided by [...]

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Bug Caused by pthread_create Input Parameters Passing

By On January 9, 2012 · Leave a Comment

0. The Context

I was working on a multi-threaded application using pthread library on Linux. One part of the application uses a thread pool with 100 threads. Each thread is supposed to finish its job and exit. The execution noramlly takes less than several seconds (we’ll call it short-living thread).

1. Locate the Bug

[...]

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