Document on SVP json format?

I want to generate svp programmatically, is there any source / SDK for it , or at least a document?
For example how long is a beat, in 64 bit integer ?

There is no documentation about the SVP, but the scripting documentation does specify the internal timing units:

QUARTER :number

Number of blicks in a quarter. The value is 705600000.

We denote musical time (e.g. a quarter, a beat) differently from physical time (e.g. one second). A blick is the smallest unit of musical time that the GUI works with internally. It is a large number chosen to be divisible by a lot of similarly purposed numbers used in music software. The name originates from Flicks.

(source: SV - Synthesizer V Studio Scripting Manual (

Unofficially, you can refer to the UtaFormatix source code. It is a web-based tool that converts project files between different singing synthesizers, and therefore already has code for both reading and writing SVP files:


The two things that you should do is examine some files using a JSON display tool, such as this:

And read through the Scripting Manual:

As claire stated, note events and durations are specified in terms of blicks. Blicks are always integer values, which is why the value of one blick is so large - 705600000. This avoids having to deal with floating point numbers, which generate rounding errors.

Open an svp file in a text editor such as Notepad++, and then drop it into the online JSON viewer:


Click the Viewer tab and you can see the structure:


Click the disclosure widgets to drill down int the structure:

The Scripting Manual hasn’t been updated in a while, so there’s a lot in the file that’s not been documented. But it will explain most of the structures, as they map directly to classes.


You might also find my notes useful, though they’re somewhat outdated.