On 18/02/2013, at 6:46 PM, iain <i...@sleepfive.com> wrote: > I'm trying to draw a sample waveform so for some of the audio files I have > which come in around 30minutes long, even drawing to a reduction of 8192 > frames/pixel you're looking at views of 10,000pixels wide (at 44100hz). > Drawing 1frame per pixel would be a view 80million pixels wide. Admittedly > that's the extreme case but drawing only the visible area is a good > performance boost, especially when I need to draw things on top of the > waveform. I do have the data points cached at certain zoom levels as well > but it's all a memory/speed trade off. I can't cache the data points at all > zoom levels, so I need to loop through the (cached) data to redraw, but > equally I can't have a pixmap backing store at each zoom level, so only > caching a pixmap of the visible area is a trade off I'm happy with.
Oldish thread now, but I just came across this, which looks highly relevant to your problem: http://supermegaultragroovy.com/2009/10/06/drawing-waveforms/ --Graham _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
