Excerpts from James Morris's message of 2010-06-17 09:57:26 +0200: > On 17 June 2010 08:20, Peter Nelson <pe...@fuzzle.org> wrote: > > On Thu, 2010-06-17 at 00:29 -0400, Jeremy wrote: > >> Hi, > >> > >> > >> When I'm programming, I find it immensely helpful to be able to plot > >> audio data at different points in its processing, for debugging, and > >> to test new ideas. > >> > >> > >> Essentially I want an oscilloscope, which plots each chunk of 1024 > >> samples. > >> > >> > >> I've tried using libplot, but it seems too slow. It's causing > >> constant xruns, even when I only plot every 5th sample. > >> > >> > >> I thought that maybe libplot was too abstract, and that I needed to > >> draw the pixels on the screen directly. I tried using SDL, but it > >> caused excessive xruns also. Simply setting 48000 pixels per second > >> was enough to cause the flow of xruns. This is *not* erasing the > >> screen, just drawing the points. I'd expect that erasing the screen > >> is the slow part, but apparently not. > >> > >> > >> At this point I'm not sure if it's even possible to plot the audio > >> data in realtime. I did a rough calculation, that on my 2 Ghz cpu, it > >> should have roughly 40,000 cycles to process each sample. It seems to > >> me that considering running the whole plugin only uses 1/4 of my cpu, > >> the other 30000 cycles should be plenty to put a pixel on the screen. > >> > >> > >> So I would guess that something else is the bottleneck, like my video > >> chip, or maybe the libraries I'm using. > >> > >> > >> So basically my question is: Has anyone else had any luck with > >> plotting audio data in real time, and if so, how? Is it not possible > >> to plot every sample, but only a certain percentage of them? Is there > >> a fundamental restriction on doing so, or is my problem in software? > > > > I'm going to assume you're plotting directly within the realtime process > > thread, which will never work. Push the audio data in a ring buffer, > > then do the plotting in your main thread. > > > > How about taking a look at some of the sound editors, snd, mhwaveedit, > etc? Or perhaps Freqtweak? > > I seem to recall seeing a reference somewhere recently, to > oscilloscope type software, which also might be useful to read the > code of, but can't remember where. > > James
Well, there's ll-scope, but no idea how close it is to what you want: http://www.student.nada.kth.se/~d00-llu/music_dssi.php?lang=en -- Regards, Philipp -- "Wir stehen selbst enttäuscht und sehn betroffen / Den Vorhang zu und alle Fragen offen." Bertolt Brecht, Der gute Mensch von Sezuan _______________________________________________ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev