We'll see | Matt Zimmerman

a potpourri of mirth and madness

linux.conf.au 2010: day 3 (morning)

Benjamin Mako Hill: Antifeatures (keynote)

Mako delivered an entertaining and inspirational talk on antifeatures, those oddities which intentionally make technology less useful to its consumers (think DRM, though he provided a wide range of examples). Mako explained the main reasons why antifeatures exist, and how they are endemic to the business of proprietary software.

Mako offered a potential upside to antifeatures, which is that they can help the free software community to focus on fundamental concerns like autonomy, rather than (for example) the mechanics of licensing. Antifeatures can be used to explain to the uninitiated why software freedom is important to everyday folks, not just hackers.

Denise Paolucci and Mark Smith: Build Your Own Contributors, One Part At A Time

Denise and Mark provided a practical list of “dos” and “don’ts” for building a successful community based on respect, empowerment and collaboration. Much of this was elementary from an Ubuntu perspective, but they offered a variety of examples from Dreamwidth which were illustrative.

Their list of “three things to start right now”:

  1. appoint a “welcomer” and laud newcomers’ first contributions
  2. stop timing out on communication when people need responses from you
  3. Have words with “that person” and let them know their behavior is not okay

Chris Double: Implementing HTML5 video in Firefox

I knew I liked this idea, but I didn’t realize how much I liked it until I watched Chris’ very informative talk. The promise of an open standard for embedding video is exciting enough, but the standard offers much more than basic embedding and playback controls. Chris demonstrated javascript-driven subtitles loaded from an SRT file, custom controls, copying and analysis of pixel data, replacing the background in a video using a chroma key technique, and even more impressive real-time special effects.

The initial implementation used the xiph.org reference libraries (libogg, libtheora, libvorbis) and PortAudio, but had some problems, including poor A/V synchronization. The second iteration used higher level libraries liboggz, libfishsound, liboggplay and libsydneyaudio, and was included in Firefox 3.1 alpha and beta, but some limitations in liboggplay (a/v sync, chained oggs, etc.) led to difficulty. There were also proof of concept implementations which used GStreamer on Linux, DirectShow on Windows, and QuickTime on MacOS, but these were hampered by codec plugin complications. In the end, they’ve gone back to using the xiph.org reference libraries (but with libsydneyaudio), though the GStreamer backend is still actively developed. Chris has published a series of articles on his blog on reading, decoding and synchronizing A/V streams using various libraries.

There are still some kinks to work out: the lack of indexes and the like in Ogg complicates seeking, calculating duration and so on, and there is no satisfactory solution for cross-platform audio. Rendering is not hardware accelerated yet because the video element is part of the HTML rendering pipeline.

It will be very powerful when it’s ready, though. Theora playback is supported in Chrome, Firefox and Opera today, and Daily Motion, Wikipedia and Archive.org are using it. I can’t wait to see the full API working well on a massive scale.


Written by Matt Zimmerman

January 19, 2010 at 23:11

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