SBL is a collection of utility custom nodes for ComfyUI. Find all six nodes in the SBL category. Each node includes a description, and its fields show help text when hovered over in a current ComfyUI frontend.

Included nodes

Global Prompt (Pos/Neg)

Keep positive and negative text prompts together, then connect either string output to other text or conditioning nodes. The fields accept multiline prompts. The node passes the entered text through unchanged and is useful when several parts of a workflow share the same wording.

Fields: positive is the positive prompt text; negative is the negative prompt text. Outputs: positive and negative strings.

Resolution

Pick common image dimensions from aspect-ratio groups (square, classic, photo, widescreen, ultrawide, phone and cinema) or enter custom width and height. Dimensions are snapped to multiple_of, which helps match the grid requirements of image and video models. The Swap width↔height button exchanges the orientation. When you expose fields from the Resolution node on a ComfyUI Subgraph, an outer Swap width↔height button appears directly below the last exposed field belonging to that Resolution node, and follows it as you reorder the Subgraph controls. The button changes the Resolution dimensions immediately, including promoted width and height values if present. If an externally connected value would be overwritten by the swap, the button leaves it unchanged. The outer Subgraph can shrink to its visible controls without extra blank space below the button.

Fields: aspect_group filters the available preset choices. width and height are selected dimensions before any megapixel limit. multiple_of determines pixel-grid snapping. max_megapixels is the maximum output area, in millions of pixels. Use 0 for no cap.

If the snapped resolution already fits the megapixel limit, the output stays unchanged. Otherwise, the node scales down to an area as close to the limit as possible while keeping the original aspect ratio as closely as the pixel grid permits. It never upscales to reach the limit. The selected width and height stay intact when changing the cap. On the outer Subgraph, the exposed megapixel field is labeled Max MP (W×H) when the cap reduces the selected dimensions, showing the effective output size; otherwise its label is Max MP. Exposed Resolution fields retain their hover tooltips. For very small caps, a 1-pixel grid may be used if the selected multiple can't fit below the limit.

Outputs: effective width and height as integers.

Math Evaluator

Evaluate mathematical expressions and short Python-style programs using a restricted interpreter. Assign results to a and b. Connect optional numeric sockets w and x (floats) or y and z (integers); unconnected values default to zero. Common mathematical functions are available, including math, statistics and cmath operations.

Fields: expressions contains the program; optional sockets w, x, y, z provide inputs. Outputs: a and b as floats, and a and b as integers (four total outputs). Evaluation failures produce zero outputs and log an error.

Example (also the node's new default):

a = w + x
b = y + z

The four optional sockets are Python-declared inputs and remain disconnected unless you connect a value. If a division is needed, use a nonzero divisor.

Seed

Produce a numeric seed and a compatible ComfyUI random-noise object. Enter seed manually for reproducible sampling, or click 🎲 Randomize to generate another seed.

Field: seed is a nonnegative integer from 0 through 9,007,199,254,740,991 (2^53 - 1), the exact-integer range supported by JavaScript. This prevents silent rounding of extremely large seeds in ComfyUI's frontend. The Randomize button continues to choose seeds below 2^50. When seed is promoted to the outside of a ComfyUI Subgraph, a matching 🎲 Randomize button appears directly below the exposed seed field and follows it when you reorder the subgraph fields. The outer subgraph also sizes itself to the visible controls, so an outdated minimum height cannot leave an unshrinkable blank area below the button and fields. Clicking it immediately changes that subgraph instance’s exposed seed, which then stays fixed until manually changed again. Each subgraph instance has its own seed; if an outside connection supplies the seed, the button leaves the connected value alone. The exposed seed field retains its hover tooltip. Outputs: integer seed and a NOISE object using that seed.

Math Scratchpad

An interactive, resizable scratchpad for calculations. Type restricted Python-style expressions, variables, math calls, loops or print() statements into the upper area, then click ⚡ Evaluate. Results and errors appear in the read-only area below. A standalone expression such as 2 * 24 + 1 now displays its answer without print(). Assignments still don't print unless requested. Drag the divider to change the amount of space available for results. This node is a utility panel and doesn't provide workflow output sockets or act as a queue output node. Clicking Evaluate runs it independently of workflow generation.

Field: expressions is the editable code area. Controls: Evaluate runs the code; the divider resizes the display; the lower field shows results.

YuE2 Instrumental Prep

Prepare a YuE2 ABC music score for instrumental generation. The node now transfers every pitched Vocal note into Ins, preserving pitch, onset and duration, and leaves rests (plus any chord symbols) in Vocal. Existing Ins melody notes are preserved wherever they don't overlap Vocal notes. When the voices overlap, Vocal takes precedence and the overlapping portion of Ins is removed so the result remains monophonic. The node validates the finished score to prevent silent melody or chord changes. When the Vocal voice already contains only rests and chord symbols, the ABC is returned exactly as supplied, without rewriting any Ins notes or accidentals. Duration, section Lyrics and diagnostic outputs are still calculated as usual.

It supports YuE2's usual two-voice ABC notation, including standard note lengths, ties, simple key/meter changes, quoted chord symbols, multi-measure rests and section comments. Unsupported constructs, such as tuplets or simultaneous note chords, produce an explicit error rather than a misleading conversion. Use the original score if you need to make a manual adjustment. It also reads recognized standalone ABC section comments such as % intro, % verse and % chorus to create section-only Lyrics tags without sung words.

The node estimates score length from the ABC time signature, tempo and bar count, then generates an upward-rounded maximum duration that includes any requested padding. The generated maximum is a ceiling, not a promise of exact song length. Empty or whitespace-only ABC inputs are treated as a no-op: all numeric outputs are 0 and all string outputs are empty, regardless of padding_seconds. Invalid nonempty ABC still produces an explicit validation error.

Fields: abc accepts an incoming ABC string; padding_seconds adds 0 to 30 seconds to the recommended ceiling. The info output reports Vocal notes transferred and Ins notes affected by overlaps. Outputs: abc (instrumental-ready score), lyrics (section tags), max_duration (rounded duration ceiling), score_seconds (theoretical duration), bars, bpm and info (diagnostics). Connect abc, lyrics and max_duration to the corresponding YuE2 generation inputs.

Installation

Copy the entire SBL folder into ComfyUI/custom_nodes/ and restart ComfyUI. Alternatively, use ComfyUI Manager if your installation supports SBL. Do not place the node files directly in custom_nodes without the enclosing SBL folder.

An old workflow using a retired, model-specific resolution node may display a missing-node warning. Replace that node with SBL → Resolution and reconnect its width and height outputs.

Dependencies

SBL uses the Python standard library and components bundled with ComfyUI. It has no separate third-party Python dependencies. Recent ComfyUI frontend versions support hover descriptions supplied through each field's tooltip metadata.

Math safety

Math Evaluator and Math Scratchpad run mathematical Python-style programs in a restricted AST interpreter instead of using unrestricted Python exec() or eval(). This prevents arbitrary code execution, imports outside the allowed math modules, filesystem operations, subprocess calls and object introspection. Execution and output size limits also apply, including checks on integer, Fraction and Decimal sizes, exponentiation, bit shifts, and formatted-string widths. These limits are resource safeguards, not a general-purpose sandbox guarantee for exposing ComfyUI to untrusted users on the public internet.

License

SBL is free software licensed under the GNU General Public License v3.0 or later. You may use, study, modify and redistribute SBL subject to the GPL terms. See LICENSE for details.