Olivier Langlois's blog

Today was my last day at StreamTheWorld. I spent the last 3 years there as the company C++ Tech Lead in charge of the company C++ streaming servers development. It has been a nice ride filled with challenges.These servers are used by over 1600 radio stations including AOL/CBS radios accessible through Winamp and Flash players.

Among my various realizations. There are:

• Scale and improve the performance and the reliability of the company audio/video streaming servers to the point where it can concurrently handles hundreds of thousands of live feeds every day in more than 25 countries, including during peak audience dayparts. The reliability and the quality of the server software have been proven to such industry leaders as CBS, Entercom, Multimedios, AOL and more. This represents 20x improvement over the original capacity.
• Added more functionality to the server by growing the server code base from 25K lines in June 2007 to 200K lines in only 2 years while improving robustness and performance.
• Designed and implemented a high performance targetted stream ad insertion system that serve end-user ads based geoip lookup. This system is now used by ESPN Radio on Internet.
• Design and implement a protocol stack to support Adobe proprietary protocol RTMP clients
• Add AAC support to the streaming server
• Improve Microsoft MediaPlayer and Silverlight support.

I will start my new job Monday next week. Visit back my blog or my LinkedIn profile if you are curious to learn for which amazing new employer I will be working for.

While I was integrating a fix to a bug that has been reported to me by Daniel Quadros in my primality testing C++ module and also adding gcc asm support to it. I used that opportunity to rework my C++ source code to HTML converter. The 2 things that I added to the converter are:

• replace the usage of the <font> tags with <span> tags in combination of CSS classes
• size optimization of the converted document

The size optimization came from the very simple observation that my converter was stateless and was not recognizing when multiple consecutive sections sharing the same colors were processed. I just added a small FSM to my converter to keep track of the current state and the converter now close the current tag only if there is a transition to a new color. The most impressive result came from my DCEL C++ file with a 25% file size reduction!

Also, I am just starting to appreciate to power of CSS. I will now be able to change the code snippet colors across my whole website by just updating a small CSS file. As a side bonus by having switched from the <font> tags to <span>, I can now use my C++ highlight feature in the code snippets contained in this blog as the blog engine was forbiding using <font> tags on posts but allows <span>.

Everyone located near Montreal and is reading this blog is welcome to join!

http://www.linkedin.com/groups?gid=2035024

The group description:

Local group for C++ professionals located in the Montreal region desiring to discuss and meet other professionals of the Montreal C++ programming industry. Join and grow your network to beat all obstacles in your career. Discuss, Seek or Share your valuable knowledge with all group mates.

Also, you are welcome to visit my LinkedIn profile to know more about me:

http://www.linkedin.com/in/olivierlanglois

AAC is a new audio codec standardized to supersede the MP3 codec. When I hear about new technologies, I am always a little skeptic since I have long understood that newer technology is too often not synonym with better technology. However, at the company that I am working for, StreamTheWorld, we have developed the first system that stream AAC through Flash players. On StreamTheWorld website, there is a demo where the player connects to one MP3 stream and to one AAC stream with the same bitrate of 48 kbps. Both streams contain the same song and the demo consists of slider that allows you to switch between the AAC version and the MP3 version. You must absolutely check the demo! (PS: Make sure that you have the latest Adobe Flash player installed as AAC playback as being added only in the latest release which is 9.0.115) The difference is so convincing that you will probably want to start converting all your music to AAC!

One note about AAC, is that there exist many versions of AAC. I am listing them in the order that they have been released:

• MPEG2 AAC
• MPEG4 AAC
• AACPlus
• AACPlus v2

All versions provide improvements over the previous versions and also provide backward compatibility. That is you could listen an AACPlus v2 stream with an MPEG2 AAC decoder. However, the additional information contained for AACPlus v2 will be discarded and the resulting audio will only be as good as an MPEG2 AAC audio stream can be. Players supporting AACPlus v2 includes:

• Adobe Flash player
• WinAmp and every player using the open source AAC decoder FAAD2.

iTunes support AAC but not AACPlus v2. Sony with its PS3 and Nintendo with the Wii gaming console have made AAC their official audio codec but I do not know which version they are supporting.

After having reported the bug to MySQL and after a lot of patience trying to explain it to the MySQL developers, they have finally verified the validity of my bug discovery and have classified it as serious!!

For the gory details of my discovery, you can consult the bug report.