VSScript.h

Introduction

VSScript provides a convenient wrapper for VapourSynth’s scripting interface(s), allowing the evaluation of VapourSynth scripts and retrieval of output clips.

For reasons unknown, the VSScript library is called VSScript in Windows and vapoursynth-script everywhere else.

At this time, VapourSynth scripts can be written only in Python (version 3).

Here are a few users of the VSScript library:

Note

If libvapoursynth-script is loaded with dlopen(), the RTLD_GLOBAL flag must be used. If not, Python won’t be able to import binary modules. This is due to Python’s design.

Structs

VSScript

A script environment. All communication with an evaluated script happens through a VSScript object.

Enums

VSEvalFlags

  • efSetWorkingDir

Functions

vsscript_init

int vsscript_init()

Initialises the available scripting interfaces.

Returns the number of times vsscript_init() has been called so far, including this call, or 0 in case of failure. This function will only fail if the VapourSynth installation is broken in some way.

vsscript_finalize

int vsscript_finalize()

Frees all scripting interfaces.

Returns the difference between the number of times vsscript_init() was called and the number of times vsscript_finalize() was called, including this call.

vsscript_evaluateScript

int vsscript_evaluateScript(VSScript **handle, const char *script, const char *scriptFilename, int flags)

Evaluates a script contained in a C string.

handle
Pointer to a script environment. If it is a pointer to NULL, a new script environment will be created and returned through this parameter. Passing NULL has the same effect as calling vsscript_createScript() first and then passing the handle obtained from that function.
script
The entire script to evaluate, as a C string.
scriptFilename

A name for the script, which will be displayed in error messages. If this is NULL, the name “<string>” will be used in error messages.

The special __file__ variable will be set to scriptFilename‘s absolute version if this is not NULL.

flags

0 or efSetWorkingDir (see VSEvalFlags).

If scriptFilename is not NULL and efSetWorkingDir is passed, the working directory will be changed to scriptFilename‘s directory prior to evaluating the script.

It is recommended to use efSetWorkingDir, so that relative paths in VapourSynth scripts work as expected.

Restores the working directory before returning.

Returns non-zero in case of errors. The error message can be retrieved with vsscript_getError().

vsscript_evaluateFile

int vsscript_evaluateFile(VSScript **handle, const char *scriptFilename, int flags)

Evaluates a script contained in a file. This is a convenience function which reads the script from a file for you. It will only read the first 16 MiB (1024 * 1024 * 16), which should be enough for everyone.

Behaves the same as vsscript_evaluateScript().

vsscript_createScript

int vsscript_createScript(VSScript **handle)

Creates an empty script environment. This function can be useful when it is necessary to set some variable in the script environment before evaluating any scripts. Like in mpv’s vf_vapoursynth filter, which passes the video to VapourSynth scripts in a variable called “video_in”.

If handle points to an existing script environment, you must call vsscript_freeScript() first to avoid leaking memory.

Returns non-zero in case of errors. The error message can be retrieved with vsscript_getError().

vsscript_freeScript

void vsscript_freeScript(VSScript *handle)

Frees a script environment. handle is no longer usable.

  • Cancels any clips set for output in the script environment.
  • Clears any variables set in the script environment.
  • Clears the error message from the script environment, if there is one.
  • Frees the VapourSynth core used in the script environment, if there is one.

Since this function frees the VapourSynth core, it must be called only after all frame requests are finished and all objects obtained from the script have been freed (frames, nodes, etc).

It is safe to pass NULL.

vsscript_getError

const char * vsscript_getError(VSScript *handle)

Returns the error message from a script environment, or NULL, if there is no error message.

It is okay to pass NULL.

VSScript retains ownership of the pointer.

vsscript_getOutput

VSNodeRef * vsscript_getOutput(VSScript *handle, int index)

Retrieves a node from the script environment. A node in the script must have been marked for output with the requested index.

Ownership of the node is transferred to the caller.

Returns NULL if there is no node at the requested index.

vsscript_clearOutput

int vsscript_clearOutput(VSScript *handle, int index)

Cancels a node set for output. The node will no longer be available to vsscript_getOutput().

Returns non-zero if there is no node at the requested index.

vsscript_getCore

VSCore * vsscript_getCore(VSScript *handle)

Retrieves the VapourSynth core that was created in the script environment. If a VapourSynth core has not been created yet, it will be created now, with the default options (see the Python Reference).

VSScript retains ownership of the pointer.

Returns NULL on error.

vsscript_getVSApi

const VSAPI * vsscript_getVSApi()

Retrieves the VSAPI struct.

This could return NULL if the scripting interface library (the Python module) expects an API version that the core VapourSynth library doesn’t provide (for example, if either library was replaced with an older/newer copy).

vsscript_getVariable

int vsscript_getVariable(VSScript *handle, const char *name, VSMap *dst)

Retrieves a variable from the script environment.

If a VapourSynth core has not been created yet in the script environment, one will be created now, with the default options (see the Python Reference).

name
Name of the variable to retrieve.
dst
Map where the variable’s value will be placed, with the key name.

Returns non-zero on error.

vsscript_setVariable

int vsscript_setVariable(VSScript *handle, const VSMap *vars)

Sets variables in the script environment.

The variables are now available to the script.

If a VapourSynth core has not been created yet in the script environment, one will be created now, with the default options (see the Python Reference).

vars
Map containing the variables to set.

Returns non-zero on error.

vsscript_clearVariable

int vsscript_clearVariable(VSScript *handle, const char *name)

Deletes a variable from the script environment.

Returns non-zero on error.

vsscript_clearEnvironment

void vsscript_clearEnvironment(VSScript *handle)

Clears the script environment.

  • Cancels any clips set for output in the script environment.
  • Clears any variables set in the script environment.