[Feature Request] [UX] Improve descriptions for "Rewind Buffer Size" and "Rewind Buffer Size Step"

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
65/100
Issue type
Documentation
Clarity
Clearly specified
Activity status
Active
Tech stack
c
Domain
documentation, frontend

Research direction

Start by locating the menu descriptions for rewind_buffer_size and rewind_buffer_size_step in RetroArch’s settings UI; the issue does not name the source file or test. Review how these entries provide sub-labels and Select-button help, then add the proposed guidance about larger buffers for memory-demanding cores. Done means both settings explain buffer sizing and step size clearly in the UI.

Written by the indexing model from the issue text.

Description

feature request
Summary

Currently, the RetroArch menu entries for Settings → Frame Throttle → Rewind → Rewind Buffer Size (MB) and Settings → Frame Throttle → Rewind → Rewind Buffer Size Step (MB) lack detailed sub-labels/descriptions explaining that higher-end or 3D system cores (such as PPSSPP) require significantly larger buffer allocations and step sizes to function correctly.

When users attempt to use Rewind on memory-demanding cores with RetroArch's default settings (e.g., 20 MB buffer size), holding the Rewind hotkey causes immediate state corruption or teleports the game back to the initial boot screen instead of rewinding smoothly.

Context & Problem Details

As discussed in https://github.com/libretro/libretro-super/pull/2164, PPSSPP's serialized save states are considerably larger than those of 8-bit or 16-bit systems. With default settings:

  • Prerequisite: Settings → Frame Throttle → Rewind → Rewind Support must be set to ON (rewind_enable = "true") for the feature to function.
  • Default Settings: Rewind Buffer Size: 20 MB / Rewind Buffer Size Step: 10 MB
  • Behavior: Holding the Rewind hotkey instantly resets the game state back to the start/menu screen because the buffer fills up almost instantly and cannot store meaningful frame history for heavy save states.
  • Working Settings for PPSSPP: Maximizing the settings—increasing Rewind Buffer Size (MB) to 1024 MB and Rewind Buffer Size Step to 100 MB—restores full, smooth rewind functionality.

Adding clearer sub-labels/help descriptions in the UI will prevent users and developers from misdiagnosing this memory limit as a lack of serialized save state support in the core.

Proposed Sub-label & Help Text Improvements
1. Settings → Frame Throttle → Rewind → Rewind Buffer Size (MB) (rewind_buffer_size)

  • Current Description:

    The amount of memory (in MB) to reserve for the rewind buffer. Increasing will increase the amount of rewind history.

  • Proposed Improvements:

    • Sub-label:

      The amount of memory (in MB) to reserve for the rewind buffer. Increasing will increase the amount of rewind history.

    • Help Dialogue Note (Select button):

      Simple 8-bit/16-bit cores require only a small buffer (e.g., 20 MB), but complex or 3D cores (e.g., PPSSPP) require a much larger buffer (e.g., up to the maximum 1024 MB) to function properly and avoid side-effects like unexpected resets.

2. Settings → Frame Throttle → Rewind → Rewind Buffer Size Step (MB) (rewind_buffer_size_step)
  • Current Sub-label Description:

    Each time the rewind buffer size value is increased or decreased, it will change by this amount.

  • Proposed Sub-label Description:

    Each time the rewind buffer size value is increased or decreased, it will change by this amount. For memory-demanding cores, increase this step size (e.g., 50–100 MB) alongside the total buffer size.

Steps to Reproduce (Demonstration of Issue)
  1. Launch RetroArch with the PPSSPP core (ppsspp_libretro).
  2. Turn Settings → Frame Throttle → Rewind → Rewind Support to ON.
  3. Keep default settings for Rewind Buffer Size (MB) (20 MB) and Rewind Buffer Size Step (MB) (10 MB)
  4. Launch any PSP game, advance past menus into active gameplay, and hold the Rewind hotkey.
  5. Result: Gameplay teleports/resets back to the initial boot state.
  6. Fix: Increase Rewind Buffer Size (MB) to 1024 MB, and Rewind Buffer Size Step (MB) to 100 MB — Rewind now works smoothly frame-by-frame.
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