Описание
# FlashbackTurbo
A Fabric addon for [Flashback](https://modrinth.com/mod/flashback) that **drastically speeds up video export — without quality loss.**
## Proven in the field
Validated across **hundreds of real anonymous exports** on **Windows (primary platform), macOS and Linux**. Export failure rate **~1%**, and every observed failure was external (not enough RAM allocated for very long replays, or the game closed mid-export) — never a regression introduced by FlashbackTurbo itself.
## What it does
Patches Flashback's export pipeline via Mixin to replace serial, low-tuned operations with parallel ones:
- **Parallel PNG writer** (N-1 threads) + configurable zlib level + RGB color-type when transparency is off
- **FFmpeg threading tunes** per encoder (`h264_nvenc`, `h264_qsv`, `h264_videotoolbox`, `libopenh264`)
- **Removes the silent 4K downscale cap**
- **Fragmented MP4** muxer on hardware encoders → ~10× faster finalize
- **Animated "Saving…" overlay** during the post-export phase
- **Fixes a Flashback crash** on mid-replay exports (null `mc.level` race)
- **Auto-promotes software → GPU encoding (0.5.0)** — when an export would use the slow `libopenh264` encoder, redirects it to a hardware encoder (NVENC/QSV) when one is available, for the ~13% of exports on software-only configs. Fail-safe, SSIM ≥ 0.99.
- **Silent auto-update (0.6.0)** — keeps your Zeffut mods up to date from Modrinth automatically: background check on launch, verified download, swap at game exit. Opt out with `"autoUpdate": false` in the config.
All hooks are opt-in via `config/flashbackturbo.json` and default to safe values.
## Performance
### Controlled benchmark (PNG sequence)
Real 1.21.11 replay, 10-second slice at 1920×1080 (603 frames):
| Mode | Total | Per frame |
|---------|-----------|-----------|
| Vanilla | 96 081 ms | 159 ms |
| Turbo | 8 774 ms | 14 ms |
**10.95× end-to-end.**
### Real-world field data (MP4 export)
Median export time across real exports (~1080p clips), by encoder:
| Platform · encoder | Median export |
|---------------------------------|--------------------|
| Windows · NVIDIA `h264_nvenc` | **~8.5 s** (60 fps) |
| Windows · Intel `h264_qsv` | ~23 s (60 fps) |
| macOS · `h264_videotoolbox` | ~26 s (30 fps) |
| Software fallback `libopenh264` | ~55 s |
Fastest on Windows + an NVIDIA GPU. A coming release auto-promotes pure-software exports to the GPU encoder when one is available.
## Quality
Lossless PNG output — zlib level only changes file size, decoded pixels are bit-identical. The FFmpeg threading tunes don't change the encoded bitstream.
## Privacy
Since 0.4.0, FlashbackTurbo sends **anonymous** usage telemetry (PostHog) to prioritise improvements: a random local UUID, no username / IP / file paths, sanitised exception messages. Fully fail-safe (it can never slow down or break an export) and **opt-out** — set `"enableTelemetry": false` in the config.
## Requirements
- [Flashback](https://modrinth.com/mod/flashback) and [Fabric API](https://modrinth.com/mod/fabric-api)
- Minecraft 1.21.9 / 1.21.10 / 1.21.11 (Java 21) — or 26.1.x (Java 25)