Virtual Orchestra From Your Own Parts

That is what this tool is for. It builds a beat grid for each recording separately and stretches a part so that its beats land on the anchor's beats, rather than picking one ratio for the whole recording. On our measurement with a live tempo drift the beats land within about 4 ms, against an audibility threshold of 50 ms; a single ratio on the same material left 158 ms.

No. The speed is changed by resynthesis rather than by playback rate, so voices and instrument tuning stay where they were. That is exactly why a part played at a different tempo can be brought to the anchor without detuning it.

Because the evidence differed. A recording with a clear attack gives a reliable beat grid, and the part is fitted beat by beat. A legato violin with no attacks barely yields beats at all — stretching by such a grid would spoil the part for the sake of a tidy number, so the tool says so and leaves it. You can always nudge it by hand.

An orchestral set: strings (violin, viola, cello, contrabass, pizzicato, ensemble), woodwinds (flute, piccolo, oboe, clarinet, bassoon), brass (trumpet, trombone, french horn, tuba), plus grand piano, harpsichord, harp and timpani.

Notes can be lifted from a recording in Audio to Notes or from a page in Sheet Music to MIDI, or played in Online Piano and Virtual Drums — all of them hand you MIDI, which this tool accepts. And if the part does not exist at all, it can be written in the Song Generator.

Yes — that is what “Play together” is for. It plays the same sound that will go into the file: the parts are already fitted, volume and pan included. Next to it you can switch on a click on the anchor's beats, so you hear not only whether it hangs together but whether the other parts landed on those beats. You can play it as many times as you like.