Passing on the Left

I haven’t written about the Dirac project recently.  We’ve reorganized a bit recently: most information is on diracvideo.org now, “Dirac” is now used to describe the overall project, with various subprojects like Schrödinger, dirac-research (formerly the Dirac codebase, intermingled with the specification), and a bunch others.  I’m finding that a lot of my time recently is cat herding all the subprojects and creating a coherent whole.

One such subproject is Bart Wiegmans’ GSoC project to implement Dirac in Java and get it working in Cortado.  It’s moving along quite nicely, and has reached the feel-good milestone of creating a pretty picture.  Right now, it only handles a very limited set of bitstreams — intra pictures only, variable length coding, and a specific choice of wavelet filter.  I think Bart has fixed a bug related to chroma handling since the time I created this screenshot, which is why it’s in greyscale.

Another subproject, and another GSoC project, is Mattias Bolte’s OpenGL decoding backend for Schrödinger.  This is roughly similar to the existing CUDA backend, although hopefully will work on a wider range of hardware.  He’s uncovering a number of resource usage issues in Schrödinger, such as the decoder using up to half a GB of RAM for temporary storage in some cases.   Alas, my hardware does not handle GLSL, so there will be no screenshots here.  The scope of the current project will require the use of GLSL, since serious signal processing is beyond clever texture hacks.

On a related note, progress is being made in gst-plugins-gl, the GStreamer OpenGL plugins.  Julien Isorce has done some amazing infrastructure work expanding on my original gst-plugins-gl code, which was really just an experiment.  At some point, the schrodec GStreamer element will decode directly in hardware using OpenGL, and then deliver the pictures as textures to downstream GStreamer elements, which will render it directly to the display.  Fillipo Argolias has been writing some cool GStreamer video filters that use OpenGL, but on a different branch than Julien’s work.  (My current task is merging these branches.) These filters will be used for Cheese.

Maarten Lankhorst has been working on a DirectShow filter for encoding/decoding Dirac streams based on Schrödinger.  It currently only works with Dirac inside Ogg, and is nearing the point where it is useful for people to use.  We’ll be doing a testing release sometime soon.

I have been working on a QuickTime component in whatever time I’ve had remaining after trying to keep up with everyone else’s work.  It works only with the QuickTime container, but it encodes and decodes pretty consistently with the Apple tools.  It’s pretty much ready for a testing release as well; just need the time to get it out the door.

Update: A screenie of Julien’s glfiltercube example (on a Mac, FTW):