Limits on Regional Time Zone Support in Blender’s Render File Path Placeholders

Answer the Core Question

Blender 2.93 and newer have no documented flag, UI control, or Python API that lets you override the system localtime() used for strftime‑style placeholders in the output path. The expansion is hard‑wired to the host’s clock and locale. Consequently, two identical renders on machines set to different time zones will produce different filenames.

Why This Matters for Distributed Pipelines

When render farms span regions, a timestamp in the filename can become a source of confusion:

• Different zones generate different dates/times for the same render event.
• Sorting by name no longer reflects the actual render order.
• Archival systems that rely on UTC‑based names may mis‑classify or duplicate files.

Confirming the Behavior on Your Build

1. Create a simple scene and set the output path to something like //render_%Y-%m-%d_%H-%M-%S_#.#.png.

2. Render one frame (Frame 1) from the command line:

   blender -b myscene.blend -E CYCLES -f 1

3. Check the generated filename. If the %Y etc. have been replaced with numbers, the placeholder is expanded.

4. Repeat the same render with TZ=UTC (Linux/macOS) or set TZ=UTC (Windows) before invoking Blender, e.g.:

   TZ=UTC blender -b myscene.blend -E CYCLES -f 1

5. Compare the two filenames. If only the time portion changes, the placeholder expansion is indeed driven by the host clock.

Practical Workarounds

• External Scheduler Injection
  Have the render‑farm orchestrator (e.g., a batch job or a Python script) compute the desired UTC timestamp and supply the full output path to Blender via the --render-output command line option. This bypasses Blender’s placeholder system entirely.
• Use Frame or Scene Identifiers
  Instead of timestamps, use the frame number, scene name, or a custom UUID in the filename. These are deterministic and independent of time zones.
• Post‑Render Normalization
  After rendering, rename files to a canonical UTC format using a small script. This keeps the original files for debugging while providing a consistent archive name.
• Environment Variable Workaround (Limited)
  Setting TZ=UTC before launching Blender will force the C library to use UTC for localtime(). However, this is a host‑level change and may affect other applications or locale‑dependent formatting in Blender.

Recommended Pipeline Step

# Example wrapper for a farm job
#!/usr/bin/env bash

# Compute UTC timestamp
TS=$(date -u +%Y-%m-%d_%H-%M-%S)

# Build the output path string
OUTPATH="//render_${TS}_#.#.png"

# Launch Blender with the computed path
blender -b myscene.blend -E CYCLES -o "$OUTPATH" -f 1

Follow‑Up Diagnostic Detail

To fine‑tune the wrapper, it helps to know whether your current Blender build expands the placeholders at all. If you find that the placeholders remain literal (e.g., render_%Y-%m-%d_#.#.png), the expansion logic may have been disabled or overridden in a custom build. In that case, please confirm the exact binary name and version you are running.

Feel free to share that detail so the recommendation can be adjusted for your environment.