On 17 June 2010 08:20, Peter Nelson <[email protected]> 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 _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
