A .sif file is the XML representation of a canvas. It holds the canvas's metadata, such as width and height, as well as information about its layers. Typically, a Synfig production comprises many .sif files joined in a sequence or nested within each other.
The .sif format is formidably complex and evolving. It is implementation-defined rather than spec-defined. Therefore, you should take everything on this page with a grain of salt. Indeed, the implementation can change at any point.
There are no plans to freeze the format.
The .sif format is implemented by the following file:
.sif files aren't always self-contained. They can import (read: link to) other .sif files, which creates a dependency of one on the other. This may seem strange to animators who use Flash because, in Flash, importing something causes it to be embedded in the current animation. One drawback of Synfig's approach is that .sif dependencies can be hard to track. A tool called RenderChan solves this problem.
Recursion of .sif files is prohibited.
Synfig recognizes .sifz as the extension of gzip-compressed .sif files. New and alternate implementations of .sif are urged to support this compression, although it is not required.
The top element of a .sif file is always a <canvas>.
<?xml version="1.0"?> <canvas version="0.1" width="300" height="350" xres="2952.7559" yres="2952.7559" view-box="-1.5 2.5 1.5 -1" antialias="2" fps="12" begin-time="0f" end-time="0f" bgcolor="0.5 0.5 0.5 1"> ... </canvas>
|Attribute||Default||What it is|
|version||no default, this attribute is required||0.1, always|
|width||480||the width of the canvas in pixels|
|height||270||the height of the canvas in pixels|
|xres||2835||the width of the canvas in pixels per meter|
|yres||2835||the height of the canvas in pixels per meter|
|view-box||-4 2.25 4 -2.25||the bounding coordinates of the canvas (left top right bottom)|
|antialias||2||how hard Synfig should try to antialias the image|
|fps||24||frames per second|
|begin-time||0||where on the timetrack should rendering start|
|end-time||0||what on the timetrack should rendering end|
|bgcolor||0.5 0.5 0.5 1.0||the color of the background in RGBA|
|focus||0 0||the anchor point for changing the view-box|
Inside a <canvas> you can find the following elements:
The short name of the canvas.
<canvas version="0.1"> ... <name>Aqua Sphere</name> ... </canvas>
Metadata for the Synfig Studio editor. These can be safely ignored by other implementations.
<canvas version="0.1"> ... <meta name="grid_show" content="1" /> ... </canvas>
Synfig Studio recognizes these <meta> names (source):
The name of the canvas's author.
<canvas version="0.1"> ... <author>King Arthur</author> ... </canvas>
A human-readable description of the canvas.
<canvas version="0.1"> ... <desc>This aqua-colored sphere reminds me of something from Mac OS X.</desc> ... </canvas>
Layers describe the shapes and effects on a canvas.
<canvas version="0.1"> ... <layer type="solid_color" version="0.1" ... </canvas>
|Attribute||Default||What it is|
|type||no default, this attribute is required||see the list of types|
|desc||a human-readable description|
|active||true||whether the layer is selected (?)|
|exclude_from_rendering||false||whether it should be rendered|