Video Decoder

Ember’s video decoder is a dual-backend native Rust module with zero-copy frame delivery into a SharedArrayBuffer.

Backends

FFmpeg (preferred)

Uses the ffmpeg-next crate. Tries hardware-accelerated NVDEC decoders first:

• h264_cuvid
• hevc_cuvid
• av1_cuvid

If hardware decode is unavailable, it falls back to software decode.

GStreamer (fallback)

Uses gstreamer / gstreamer-app crates with a pipeline:

uridecodebin → videoconvert → appsink

Why two separate .node files

FFmpeg and GStreamer link against different C libraries. If both were linked into the same .node, missing runtime libraries would prevent the addon from loading at all.

By building two variants and trying them at runtime, Ember gracefully degrades if only one set of libraries is present:

• video-decoder-ffmpeg.node
• video-decoder-gstreamer.node

Renderer integration

Component	Purpose
useNativeVideo.ts	React hook managing decoder lifecycle, SAB, WebGL renderer, and rAF frame pump
webgl-renderer.ts	WebGL texture renderer for RGBA frames
VideoPlayer.tsx	Dual-mode player: <video> element for MP4/WebM/H.264, native decoder + WebGL canvas for MKV/HEVC
video-decoder.service.ts	Main-process service that loads the correct .node backend at runtime
ipc/index.ts	IPC handlers bridging renderer → main → Rust decoder

URL resolution

Before passing URLs to FFmpeg, Ember resolves them:

• ember://media/<path> → local filesystem path
• ember://remote/<sourceId>/<path> → http://localhost:<port>/<path>