VF Autosave Render + Output Variables

Automatically saves a numbered or dated image after every render and extends the Blender output path and compositing output node with dynamic variables. This Blender add-on helps automate file naming (enabling easier and more advanced production workflows) and makes test renders easier to review and compare (saving what would otherwise be overwritten or lost when quitting the app).

Installation and Usage

• Download VF_autosaveRender.py
• Open Blender Preferences and navigate to the "Add-ons" tab
• Install and enable the add-on
• It will be enabled by default in the Render Output panel, where you can customise the automatic file output settings

Warning — Version 2 of this add-on changes the capitalisation of the file, and will fail to install or run correctly if prior versions are not fully cleared from the system before upgrading. Restarting Blender may be necessary in-between uninstalling older versions and installing this update.

Global Preferences

Add-on preferences are found in the Blender Preferences panel add-on tab, at the bottom of the plugin listing. These settings apply globally to all projects except for the project render time value which is saved within the project file.

Preferences

• Render Output Variables enables dynamic variables in the output file path
• File Output Node Variables enables dynamic variables for the path and all image outputs of a single Compositing tab node named "File Output" (see the Compositing Node Variables section below)

Render Time

• Show Project Render Time toggles the "total time spent rendering" display in the Blender Output panel
  • Total Render Time allows manual resetting of the projects render tracking (this is the only per-project value visible in the plugin settings panel)
• Save External Render Time Log enables tracking of render time outside of the Blender file, supporting command line rendering or tallying the render time for all Blender projects in the same directory
  • Sub-folders and relative paths can be used (not absolute paths)
  • Only the {project} dynamic variable is supported
  • The default string {project}-TotalRenderTime.txt will save a dynamically labeled file alongside the project (logging render time per-project since each log file would be named per-project)
  • Using TotalRenderTime.txt will allow all Blender files in the same directory to use the same log file (logs would be per-directory, not per-project)
  • Whereas {project}/TotalRenderTime.txt will save the log file inside the default autosave directory (this is specific to MacOS and Linux; backslash would be required in Windows)
• Estimate Remaining Render Time will display in the render window menu bar an estimation for how much time is left during animation rendering
  • This isn't particularly accurate, especially during the first few frames or in scenes with a great deal of variability in render time from frame to frame, but can give a general guess as to how much render time remains

Global Autosave Overrides

• This section allows for overriding autosave settings globally, making it much easier to set up a single location for all autosaved renders, along with consistent name formatting and file types, including for files created prior to setting up Autosave Render
• The global override settings are the same as detailed below, and any elements that are overridden will be greyed out (though still editable) in the project's Autosave Render panel

Autosaving every render is a per-project setting, and is enabled in the Render Output panel where the project settings are located. This is not an overridable setting yet.

Project Settings

Project settings are found at the bottom of the Render Output panel and are unique per-project. The add-on can be disabled here by unchecking Autosave Render but is turned on by default.

• Variable List

  • This popups up a reference panel with all of the variables that can be used in either the file location or custom string strings below

• Serial Number

  • This is the local project serial number for autosaved files, independent of the project serial number for output files, and will be unused if file location or file name inputs are replaced with a global override in the Blender Preferences > Add-on window
  • It will be greyed out when unused (if the variable {serial} does not appear in the file location or custom string inputs)

• Autosave Location

  • Leave a single forward slash / to automatically generate a folder with the same name and in the same directory as the Blender project
  • Or select a specific directory such as /project/renders/autosave/ to automatically save all renders to the same location

• File Name

  • Project Name + Serial Number uses the name of the Blender file and an auto-generated serial number (it will detect any existing files in the autosave location and increment the highest number found)
  • Project Name + Date & Time uses the name of the blender file and the local date and time (formatted YYYY-MM-DD HH-MM-SS using 24 hour time)
  • Project Name + Render Engine + Render Time uses the name of the blender file, the name of the render engine, and the time it took to render
    • When a sequence is rendered, only the final frame will be saved and this value will be the total sequence render time, not the per-frame render time
  • Custom String uses pattern replacement to allow for entirely unique file naming patterns
    1. Project variables
    • {project} = the name of the Blender file
    • {scene} = current scene being rendered (if multiple scenes are used in the compositing tab, only the currently selected scene name will be used)
    • {collection} = active collection (if no collection is selected or active, this will return the root "Scene Collection")
    • {camera} = render camera (independent of selection or active status)
    • {item} = active item (if no item is selected or active, this will return "None")
    2. Rendering variables
    • {renderengine} = name of the current rendering engine (uses the internal Blender identifier)
    • {device} = CPU or GPU device
      • Workbench and Eevee always use the GPU
      • Cycles can be set to either CPU or GPU, but multiple enabled devices will not be listed
      • Radeon ProRender can use both CPU and GPU simultaneously, and in the case of multiple GPUs, additional active devices will be added as "+GPU"
      • LuxCore can be set to either CPU or GPU, but multiple enabled devices will not be listed
    • {samples} = number of samples
      • Workbench will return the type of antialiasing enabled
      • Eevee will return the total number of samples, subsurface scattering samples, and volumetric samples
      • Cycles will return the adaptive sampling threshold, maximum samples, and minimum samples
      • Radeon ProRender will return the minimum samples, maximum samples, and the adaptive sampling threshold
      • LuxCore will return the sample settings for adaptive strength, warmup samples, and test step samples (Path) or eye depth and light depth (Bidir)
      • All outputs reflect the order displayed in the Blender interface
    • {features} = enabled features or ray recursions
      • Workbench will return the type of lighting used; STUDIO, MATCAP, or FLAT
      • Eevee will list abbreviations for ambient occlusion, bloom, screen space reflections, and motion blur if enabled
      • Cycles will return the maximum values set for total bounces, diffuse, glossy, transmission, volume, and transparent
      • Radeon ProRender will return the maximum values set for total ray depth, diffuse, glossy, refraction, glossy refraction, and shadow
      • LuxCore will return the halt settings, if enabled, for seconds, samples, and/or noise threshold with warmup samples and test step samples
    • {rendertime} = time spent rendering (this is calculated within the script and may not exactly match the render metadata, which is unavailable in the Python API)
    3. System variables
    • {host} = name of the computer or host being used for rendering
    • {platform} = operating system of the computer being used for rendering (example: "macOS-12.6-x86_64-i386-64bit")
    • {version} = Blender version and status (examples: "3.3.1-release" or "3.4.0-alpha")
    4. Identifier variables
    • {date} = current date in YYYY-MM-DD format, a shortcut for the individual variables below
    • {Y} = current year in YYYY format (note the capitalisation differences)
    • {y} = current year in YY format
    • {m} = current month in MM format
    • {d} = current day in DD format
    • {time} = current time in HH-MM-SS 24-hour format, a shortcut for the individual variables below
    • {H} = current hour in HH 24-hour format
    • {M} = current minute in MM format
    • {S} = current second in SS format
    • {serial} = automatically incremented serial number padded to 4 digits
    • {frame} = current frame number (padded to four digits)

• Serial Number input field is enabled only when the text {serial} appears in the File Location or Custom String fields, and automatically increments every time a render is saved (files may be overwritten if this counter is manually reset; both a feature and a danger!)

Warning — using a custom string may result in overwriting or failing to save files if the generated name is not unique. For example; if date and time or serial number variables are not included.

• File Format
  • Project Setting will use the same format as set in the Render Output panel (see note below about multilayer EXR limitations)
  • PNG
  • JPEG
  • OpenEXR

File formats will use whatever compression preferences have been set in the project file. If you want to render animations using the PNG format, but save previews using JPG with a specific compression level, temporarily choose JPG as your Blender output format and customise the settings, then switch back to PNG. When the add-on saves the render file, it'll use the (now invisible) JPG settings saved in the project file.

Render Output Variables

If enabled in the add-on preferences, this extends the native Blender output path with all but one of the Custom String variables listed above (the {rendertime} variable is not available because it does not exist before rendering starts when these variables must be set). If the keyword {serial} is used anywhere in the output string, the Serial Number value will be displayed. Click the Variable List button to see a popup of all available keywords.

This works well for automatic naming of animations because the variables are processed at rendering start and will remain unchanged until the render is canceled or completed. Starting a new render will update the date, time, serial number, or any other variables that might have been changed.

Compositing Node Variables

If enabled in the add-on preferences, this extends the native Blender output path with all but one of the Custom String variables listed above (the {rendertime} variable is not available because it does not exist before rendering starts when these variables must be set). If the keyword {serial} is used anywhere in the base path or file subpath strings, the Serial Number value will be displayed. Click the Variable List button to see a popup of all available keywords.

This feature supports customisation of both the Base Path and each File Subpath (image name) in the node. There is a limitation however; only one File Output node is supported, and it must be named "File Output". Any additional output nodes will be ignored. If multiple output directories are needed, the workaround is to include the folder paths within the specific image output names, not the base path.

Like the render output variables feature, this fully supports animations, including the date and time variables which are set at render start (not per-frame).

Estimated Render Time Remaining

When enabled in the plugin preferences, Autosave Render can track elapsed time during animation rendering and calculate a rough estimate based on the number of frames completed and remaining. While far from accurate in cases where per-frame render time is inconsistent (the first few frames will be particularly inaccurate), it can give a general idea of how much longer the animation may take to complete.

Notes

• Autosave Render depends on the Blender project file having been saved at least once in order to export images, otherwise there is no project name or local directory for the add-on to work with (an alternative branch that supports unsaved projects is available in this older branch)
• Only the final frame will be autosaved when rendering sequences, preventing mass duplication but still allowing for total render time to be saved in the file name (depending on settings)
• Total internal render time will continue to increment even when auto file saving is toggled off in the output panel
• Total internal render time will not increment when rendering files from the command line, since it depends on being saved within the project file (the command line interface doesn't typically save the project file after rendering is completed)
• The Blender Python API image.save_image has a known bug that prevents the saving of multilayer EXR files, saving only a single layer file instead (I'm not aware of any reasonable workarounds, just waiting for it to be fixed)
• This add-on is provided as-is with no warranty or guarantee regarding suitability, security, safety, or otherwise. Use at your own risk.