storytold/filmcraft

Running into the same issue, tried tweaking a bunch in app and on my system to no avail...

System:
Kernel: 7.2.9-1-cachyos arch: x86_64 bits: 64
Desktop: KDE Plasma v: 6.7.5 Distro: CachyOS
Audio:
Device-1: Intel 300/C240 Series Family HD Audio driver: snd_hda_intel
Device-2: NVIDIA GP106 High Definition Audio driver: snd_hda_intel
API: ALSA v: k7.2.9-1-cachyos status: kernel-api
Server-1: PipeWire v: 1.6.9 status: active

## Also getting audio issues.

- Manjaro
- Pipewire

## Error
- ALSA lib pcm_dmix.c:1000:(snd_pcm_dmix_open) [error.pcm] unable to open slave

**Correction to my earlier update on #33.** VideoToolbox hardware decoding was **not** active in the desktop app until #41 (merged today, 5c8471c).

The desktop app called `filmcraft_platform::register()` only as an argument to `log::info!`. No logger is installed, so the `log` crate never evaluated it and the hardware decoder was never registered. The CLI/MCP and the benchmark harness call `register()` directly. That's why the parity tests and the benchmark numbers in #33 were real, and also why we didn't notice that desktop users, v0.2.0 and v0.2.1 included, still decoded in software.

#41 (by @justjohn12345) registers it unconditionally at startup and adds a test that it happens without a logger. The next release is the first where desktop users get hardware decoding by default. I missed this in review; thanks to the contributor for catching it.

**31 common effects now run on the GPU** (#35, merged).

On the GPU:
- **colour:** Brightness & Contrast, ProcAmp, Tint, Black & White, Color Balance, Levels, Gamma, Channel Mix, ASC CDL, Leave/Change/Pass/Replace Color, Invert, Posterize, Extract, Alpha Adjust;
- **geometry:** Crop, Flip, Transform, Mirror, Offset, Edge Feather;
- **blur:** Gaussian, Camera, Directional;
- **sharpen:** Sharpen, Unsharp Mask.

A clip moves to the GPU when all of its effects are on this list; otherwise it renders on the CPU as before. GPU output matches the CPU reference to within 7e-5 relative on 78 cases, including extreme parameters. On a three-layer test with effects, frame-worker time drops from 220–307 ms to 1.8–93 ms per frame.

**Done so far:** blend modes (#32), macOS hardware decode (#33), common effects (#35).

**Next:**
- VA-API (Linux) and Media Foundation (Windows) decode;
- zero-copy upload of decoded frames;
- Lumetri, keys and masks on the GPU;
- moving effect passes off the UI thread;
...

**Hardware decoding on macOS is in** (#33, merged).

H.264 and HEVC (8/10-bit, 4:2:0 and 4:2:2) now decode on VideoToolbox's hardware decoder. It's on by default, and Settings ▸ Playback ▸ Hardware decoding switches it off. Output is bit-exact with our software decoders on every test stream. If the hardware fails mid-stream, decoding continues transparently in software.

Apple M4 Pro, load average 150–190, Off → Auto:

| | CPU ms per frame | fps |
|---|---|---|
| H.264 2160p decode | 119 → 4.2 | 35 → 107 |
| HEVC 2160p decode | 86 → 3.7 | 49 → 217 |
| 4K H.264 playback at Full resolution (frames shown/dropped) | ~120 → ~9 | 104/88 → 192/0 |

This also adds `crates/platform`, the one crate allowed `unsafe` for OS media APIs. Linux (VA-API) and Windows (Media Foundation) backends will plug into it.

**Next:**
- effects on the GPU (in progress);
- VA-API for Linux and AMD, which needs a Linux machine to test;
- Media Foundation for Windows;
- passing decoded frames straight to the GPU wit...

Progress: **blend modes now run on the GPU** (#32, merged).

All 27 blend modes composite in WGSL, Dissolve included. A clip with a blend mode no longer forces the whole frame through the CPU renderer. The GPU output matches the CPU reference: every mode is within one half-float step on the edge-case tests, and 99% of interior pixels are within one 8-bit level on full sequences.

On a 1080p three-layer stack with Screen and Overlay, playing at Full resolution:

| | shown/dropped frames | CPU ms per frame |
|---|---|---|
| before | 19/173 and 138/54 | 168–214 |
| after | 191/1 and 192/0 | 86–87 |

That's the same cost as the plain Normal stack.

**Coming next:**
- **#33** adds hardware decoding on macOS through VideoToolbox, plus the `crates/platform` FFI crate that the Linux (VA-API) and Windows (Media Foundation) backends will use. It's in final CI. 4K H.264 decode drops from 119 to 4 CPU-ms per frame.
- The most common effects (colour adjustments, crop, flip, transform, Gaussian blur...