Tuesday, September 02, 2008

Sound integration

The work with integrating the GSoC projects into the Ember trunk have continued. I've now merged the Sound Manager changes that Romulo have provided into the main trunk. In the process I had to do some alterations to the code though. While the code provided by Romulo worked and did indeed play sounds it made some assumptions that made it not so suitable for the very dynamic nature of the entity world. Since we can't know beforehand what kind of entities that we need to show, and must be able to dispose of and create new entities as we move through the world we must make sure to provide good resource handling. The changes I made to the way the SoundService works have much to do with how sound sources and buffers are allocated and handled. I've worked with the assumption that not too many sounds will be playing at any time, and that once a sound has finished playing it should be deallocated.
The original code also worked with the assumption that all sounds allocated from ogg files were "streaming" sounds, while all sounds allocated from wav files were "static" sounds (i.e. where the whole sound could be kept in memory). However, the notion of "streaming" and "static" only relates to how large the sound buffer is, not how it's stored (in ogg or wav). Any sound that is too large should be streamed, which means that it should be read from disk in increments. And any sound that is very small could be kept in memory, making it "static".
As I've reworked the SoundService I've temporarily disabled the support for loading ogg sounds, as the implementation needs to be able to handle data recieved from the Ogre resource system. It should however return as I sort out the code.

With the sound support now in Ember trunk I'll start looking at polishing up the code and updating the media for a 0.5.4 release pretty soon.
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