Original_Speeder

The game had a serious problem: The awesome music from xaimus, caused slow-downs and buffer underruns, resulting in the music stuttering (among other undesired effects)

The reason for that, is how ClanLib handles streaming music: It waits for the buffer to end, and then it requests a hardcoded amount of data (1024*16 bytes), if this data is not calculated until the soundcard needs it, the result is a underrun.

The solution then was actually simple in theory, but hard to do for someone that never did it before, I would need to implement a ring buffer, and fill it in the background...

First, explaining what is a ring buffer: A ring buffer, is a buffer of fixed size, that you keep filling data, and reading data from it when necessary, when you read data, you overwrite the data that you just read with new data, it is called ring buffer, because when you reach the end, you start again in the beginning. This solve the problem because I fill it in advance, thus even if the music player slows-down it will take some time until it gets empty.

To fill it without slowing down everything else, or locking-up the game, I decided to make it in the background, so I learned how to use pthreads, a library to make threads (heh, you could not guess it, could you? :P), and it was really simple, all I needed to do was fire-up the player in another thread, and the player constantly fills the buffer, while clanlib reads the buffer, and both of them, before messing with the buffer, check if the other one is using it, so it avoid conflicts.

Although simple to do in theory, I never did that before, and I had several issues, first I accidentally made the buffer misbehave, by forgetting that it had stereo music, thus all addresses should have their values doubled, then I made some logic bugs, and some corner cases that caught me by surprise, like what happened when both pointers went to "0" but the buffer was full, the result was it re-filling again, resulting in the music suddenly skipping forward some seconds. Also I had the usual crashes caused by newbie errors, and etc...

After some extensive testing, seemly this solved all problems regarding music, now the game can play the awesome xaimus music without hassles! And I must say, that xaimus music is AWESOME! (well, for what other reason I would put it in the game?)