v1.4.0 — High quality HEVC and USB link status

This release adds a built-in High quality HEVC preset, fixes HEVC rate-control handling, and shows whether the Valve dongle is actually connected at USB 2 or USB 3 speed.

• High quality HEVC: 400 Mbps target, 90 Hz, 10-bit, 2048-pixel stream width, CBR without padding, quarter-resolution multipass, asynchronous sending, and center/peripheral quality offsets of −2/−6.
• Editable settings: load the preset for review, change individual controls in Stream settings or Advanced, and save your own version. Built-ins remain separate from personal presets. HEVC now exposes the 90/120 Hz refresh preference, and Apply from Advanced applies the complete loaded preset.
• Encoder fixes: correct NVENC rate-control capability flags and retain the last accepted mode when the encoder cannot change it until reinitialization. Improve high-bitrate H.264 buffer-limit signaling and entropy selection.
• USB status: report the dongle's negotiated USB bus speed, with explicit unknown/stale states and USB 2 guidance. This is separate from Wi-Fi rate and measured video throughput.
• Codec reliability: tolerate transient Windows heartbeat-file sharing conflicts and preserve encoder initialization diagnostics before recovery.
• Research tools: include the standalone SteamVR multistream prototype and HEVC decoder/timing experiments in source. The app's normal streaming path remains single stream; the prototype is not a supported 400+ Mbps gameplay mode.

The bitrate setting is a target, not a guaranteed delivered rate. A 270-second Galactic Racer observation at this HEVC setup averaged 274.71 Mbps of coded video and 89.70 encoded fps. Presentation timeouts and PC drops still occurred. See the included high-quality HEVC guide for the controls, observations and limits. Gaze offsets change compression quality, not the physical tracked-region size.

Validation: 65 managed tests (including patch/restore tests with verified local fixtures), six native encoder tests, 13 codec-companion tests, three multistream session tests, and 25 compositor-timing assertions passed. Windows/Frame multistream contracts and Frame decoder crop/framing tests passed. The self-contained package's contents, fresh compiled UI resources, codec runtime imports and decoder fingerprint were verified. Live gameplay was not restarted for release packaging.

Download SteamLinkVRSettings-SteamFrame-win-x64.zip, extract the entire folder and run SteamLinkVRSettings.exe. SHA256SUMS.txt verifies the ZIP. The bundle includes the codec companion/runtime and the experimental decoder's corresponding source; it excludes personal configuration, credentials, captures and original Valve binaries.