Re: [LAD] on the soft synth midi jitters ...

Cubase is particularly bad when playing a soft-synth live, esp with larger audio buffer sizes, because even though VST supports sample-accurate MIDI, all note-ons are sent with timestamp of zero (the exact start of the buffer). It's like trying to play drunk, like glue in the keys, I keep looking at my fingers thinking "did my finger slip off that note?". Playing a pre-recorded MIDI tract is different, timestamps are then honoured. Why did Steinberg implement it like this?, I think it's a misguided attempt at reducing latency. It's doesn't, the worst case notes are still delayed exactly one 'block' period. There's no upside. It's far better to have small latency and no jitter because your brain will compensate very accurately for consistent latency, you will instinctively hit the keys a fraction early. All will sound fine. Jitter is baked-in timing error, once it's in your tracks you can't get it out. Latency can always be compensated for and eliminated later. The right way is to timestamp the MIDI, send it to the synth delayed by one block period. Since audio is already buffered with the same delay, you will get perfect audio/MIDI sync. IMHO - After writing my own plugin standard, sample-accurate MIDI is no more difficult to support than block-quantized MIDI. Jeff McClintock > Message: 8 > Date: Tue, 5 Oct 2010 21:22:23 +0100 > From: Folderol &lt;folderol(a)ukfsn.org&gt; > Subject: Re: [LAD] on the soft synth midi jitters ... > To: linux-audio-dev(a)lists.linuxaudio.org > Message-ID: <20101005212223.5a7fbb61@debian> > Content-Type: text/plain; charset=US-ASCII > > On Tue, 5 Oct 2010 22:00:11 +0200 > fons(a)kokkinizita.net wrote: > > > On Tue, Oct 05, 2010 at 02:50:10PM +0200, David Olofson wrote: > > > > > Not only that. As long as the "fragment" initialization overhead can > be kept > > > low, smaller fragments (within reasonable limits) can also improve > throughput > > > as a result of smaller memory footprint. > > > > 'Fragment initialisation' should be little more than > > ensuring you have the right pointers into the in/out > > buffers. > > > > > Depending on the design, a synthesizer with a large number of voices > playing > > > can have a rather large memory footprint (intermediate buffers etc), > which can > > > be significantly reduced by doing the processing in smaller fragments. > > > > > Obviously, this depends a lot on the design and what hardware you're > running > > > on, but you can be pretty certain that no modern CPU likes the > occasional > > > short bursts of accesses scattered over a large memory area - > especially not > > > when other application code keeps pushing your synth code and data out > of the > > > cache between the audio callbacks. > > > > Very true. The 'bigger' the app (voices for a synth, channels for > > a mixer or daw) the more this will impact the performance. Designing > > the audio code for a fairly small basic period size will pay off. > > As will some simple optimisations of buffer use. > > > > There are other possible issues, such as using FFT operations. > > Calling a large FFT every N frames may have little impact on > > the average load, but it could have a big one on the worst case > > in a period, and in the end that's what counts. > > > > Zyn/Yoshimi uses FFTs for some of its algorithms IIRC. Getting > > the note-on timing more accurate could help to distribute those > > FFT calls more evenly over Jack periods, if the input is 'human'. > > Big chords generated by a sequencer or algorithmically will still > > start at the same period, maybe they should be 'dispersed'... > > > > Ciao, > > I'm all in favour of a bit of dispersal. > > When I started out with a Yamaha SY22 and Acorn Archimedes it was all > too easy to stuff too much down the pipe at once. However, doing some > experimenting, I was surprised at how much you could delay or advance > Note-On events undetectably although it depended to some extent on the > ADSR envelope. > > I don't need to do that any more, but old habits die hard, so if I'm > copy-pasting tracks I tend to be deliberately a bit sloppy. > > > -- > Will J Godfrey > http://www.musically.me.uk > Say you have a poem and I have a tune. > Exchange them and we can both have a poem, a tune, and a song.