Hi everybody, Just an update on what I've been poking around at.
I'm trying to figure out how to implement looping, and in the process I've spent a lot of time staring at how EngineBuffer works. Anybody with some experience here please do chime in and correct anything I've gotten wrong or give background/history of some of what is in here. I made a brief summary of how EngineBuffer::process works. Interestingly enough, it actually has some looping code baked into it, and after looking at it more and more it looks like it might have worked at one point. Does anybody know if it ever did work? Furthermore, there's this 'crossfading' thing inside of EngineBuffer. As far as I can tell, the crossfading is supposed to happen when you ask for a beat-synchronized loop so that there is less abrupt jumping between the end of the loop and the start. Does anybody know the intent or who wrote the crossfading stuff? (keep in mind, this is inside one engine buffer, not crossfading between two enginebuffers). I'm leaving out some minor details and summarizing some of the parts there. Basically I'm trying to find a way to split up this beast and segment whatever is possible into a submodules. EngineBufferCue is a good example of this. All the cueing stuff happens and the logic/control objects/state aren't crammed into EngineBuffer. If anyone's interested in checking out what I'm working on, I'm doing my work in branches/Features_rryan-looping Also the wiki page for the looping spec is here http://mixxx.org/wiki/doku.php/looping The following is meant for a monospace font, so sorry if it doesn't show up that way. (I'm sending HTML email in the hopes that setting mono works). I'll be making a wiki page about EngineBuffer soon. Logic summary of EngineBuffer::process(): PAUSE-LOCK READER-LOCK get file buffer variables from reader READER-UNLOCK - Calculate rate for this section of audio - start with base rate of audio - take into account wheel moving - do scratch rate shifting - if rate changed, set it in the scale object === do audio processing for this round === - if rate==0 or at extents then ramp-out - else (do scaling of audio) - if not crossfading - if looping - do looping using temporary buffer - scale the temporary buffer using the scaling engine - else (not looping) - scale the audio using the scaling engine object - else (crossfading) - if crossfade finished - scale the audio using the scaling engine object - else - crossfade in temporary buffer - scale the temporary buffer using scaling engine - copy pOutput[i] = output[i] for buffersize === update internal state === - update filepos_play - detect at_end, at_start - 'ensure valid range of idx' (idx = idx % READBUFFERSIZE) - bufferpos_play = idx - if we have new reader info (and filepos_end>0 ??) - Wake reader so it reads more data from the sound file - Notify listeners of changes (playposition slider, visual waveform) - End of Track Mode processing (next-track, loop, etc) PAUSE-UNLOCK - ramp-out if we just paused - force ramp-in if previously paused Cheers, RJ ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Mixxx-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mixxx-devel
