0.09 seconds of desync in each recording take?

[cynlic]

Hi everyone,

I've been checking out Radium for a day or two in the hopes that, once I grok the demo, I'll be able to subscribe and use it for all sorts of fun Pd nonsense. I've really enjoyed everything so far, other than one problem which I couldn't seem to find an answer for in the forum backlog.

To test everything out I've just been trying to record a little garage rock tune (so just using the sequencer view). The issue that I've found is that every take seems to have about 0.09 seconds of audio before where the first beat should fall, causing desync that you have to manually fix every time. I eventually tested this by recording the metronome with my microphone (see screenshot attached below). I've tried flipping on and off the latency setting to no avail.

I thought the problem might be jack, but I did the same process in Reaper with jack as the audio device and there wasn't much of a problem -- way less than 0.09 seconds.

Is there a work around for this? I realize that the editor block is probably the more typical way to use Radium, but it would be really helpful if I didn't have to switch to Reaper for things where I know I'm going to be recording a lot of takes.

(Note: In the screen shot I've trimmed the file to measure the desync)


Many thanks y'all!

[kjetil]

Hi,

I haven't compensated for input latency when recording from system input, so some latency is to be expected. 0.09 sounds sounds like the expected latency if you are running 2 periods of 1024 frames latency. This is of course not acceptable behavior of the program, so I'll prioritize fixing this.

[kjetil]

There is a workaround though. In the mixer, you can add a "TimeSkew" plugin for each "Seqtrack" instrument. In the timeskew plugins, set the skew value to -90ms.

[cynlic]

Thanks so much for your quick reply! It's amazing that you maintain this software and are so responsive on the forums.

You definitely guessed the jack buffer settings correctly. I just tried the time skew plugin, and I have to admit that I'm having trouble figuring out how to use the non GUI plugins. I assume you have to use FX text and then convert -90ms to a hex value which translates to somewhere between 0%-100% of the skew effect? I'm not sure exactly how much it skews at the moment, so it's a bit hard to calculate!

Thanks again!

[kjetil]

Hi,

You don't need to use automation / fxtext to set effect value. Press F9 to show the instrument widget, or press the "Instrument" tab below the editor. There should be a "Skew" slider there for TimeSkew plugins.

[kjetil]

(Skew should be as close as possible to -92.88 if using samplerate of 44100, or as close as possible to-85.33 if using samplerate of 48000. Press Ctrl-key to finetune mouse movement.)

[kjetil]

After studying soundcard latency a little bit, I think the latency ideally should be around 70ms for 1024 buffers (one buffer for recording, and two buffers for playback). But both hardware and drivers may add extra latencies that I can't know of. For instance, I read somewhere that USB soundcards can add an extra buffer when recording. My point is that for the next version of Radium, the default recording latency will probably be set to 70ms, and not to 90ms, so you have to set this value manually to 90ms in the preferences before recording.

[cynlic]

(Skew should be as close as possible to -92.88 if using samplerate of 44100, or as close as possible to-85.33 if using samplerate of 48000. Press Ctrl-key to finetune mouse movement.)

Thanks so much -- this worked like a charm with my metronome test.

But both hardware and drivers may add extra latencies that I can't know of. For instance, I read somewhere that USB soundcards can add an extra buffer when recording.

Interesting. I'm using the typical Focusrite scarlet 2i2. It's not exactly top of the line, so I wouldn't be surprised if there's some extra buffering going on. As I said before, Reaper seemed to have some visible latency but it was miniscule enough that I didn't hear much time slipping, particularly once I started double tracking, adding reverb, etc. I should've written down what it was but I didn't. I'll check and see if it's ~20ms when I get a chance.

My point is that for the next version of Radium, the default recording latency will probably be set to 70ms, and not to 90ms, so you have to set this value manually to 90ms in the preferences before recording.

Sounds perfectly reasonable to me!