Paulo164 wrote:Paulo164 wrote:gabe wrote:I would be very interested in seeing what you find. The way I did it is to use a second computer for measurement. I.e. use you normal computer for pianoteq and not for measuring. The measurement computer had a sound device where I recorded the analog output of the piano and at the same time either the analog sound output of the Pianoteq computer or a microphone for acoustic. If you have more than two inputs on your recording device you can do all three at once. Keep mic not too far from strings (a meter already adds 3 ms), in the middle. It helps a lot if the environment is silent (i.e. you only have your piano sound in the mic recording). It helps if you have both a spectrogram and wave form for measurement, but timing should be determined from the wave form. Low frequency noise can mess up the acoustic measurement, so you could filter that out, but make sure you filter all signals the same way. Good luck!
PS For those interested, there is an interesting paper on temporal dynamics of a grand piano here: https://www.researchgate.net/publicatio...no_actions
Hello,
Dully noted. However, I don't intend to measure the absolute latency of my setup. The purpose is to measure how the "acoustic" latency increases/decreases according to the incoming velocity. So I will setup on purpose a high latency on the digital part so that the 2 peaks ("acoustic" and "digital" ones) are well separated on the timeline, making reading the measurement easier.
In a second time, I will do a measurement with the minimum possible digital latency to see if I can get as close as possible to the latency of my acoustic piano.
Just to let you know I have done some measurements but it appears there is 2 peaks due to 2 phenomenons when pressing a piano key : first the hammer noise (quite tiny), then the string noise (much louder).
I think that the acoustic piano "latency" should be measured as soon as the hammer noise appears. So I must do again my measurements with this in mind, otherwise it's pointless.
I will keep you posted.
Sorry to come back so late to this thread !!
Here are my conclusions :
Depending on the speed you depress a key, there is an offset between the time the hammer in an acoustic piano hits the string and a MIDI controller triggers the sensor to produce the Note-On event.
Let’s assume the string and the sensor are triggered at the same time when you play forte. Then you will have a delay up to somewhere 5 to 10 ms when you play softly for the digital piano. Said differently, the digital piano is late compared to the acoustic one when playing softly.
This delay increases from 0 to 10 ms when velocity decreases from 127 to 1.
I explain this phenomenon by the fact the digital piano triggers the note-on always at a fixed distance of the key to the keybed, whereas on the acoustic piano there is a coordinate/speed equation much more subtle occurring.
As a consequence, a perfect digital piano should trigger very early its note-on events and apply a variable delay depending on the velocity.
By doing so, the main issue is you will loose precision because triggering early the sensor implies you measure the speed on a shorter distance.
So it is a trade-off to find here between accuracy of the measured velocity and accuracy of the timing.
Please note that I purposefully ignore the system latency in this reasoning. This is out of scope.
Thanks.
