fix(transcode): only pick a GPU encoder when its device is present#5
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…resent detect_hw_encoder() in 'auto' mode picked nvenc as soon as ffmpeg *listed* h264_nvenc — even on a host with no NVIDIA GPU. The encoder is compiled into many ffmpeg builds, so on a GPU-less server transcoding failed at runtime with "[h264_nvenc] Cannot load libcuda.so.1 / Error initializing output stream", and the player showed "invalid video source". Observed in production (no GPU, ffmpeg shipping nvenc). Now nvenc requires a real NVIDIA device (/dev/nvidia0 or /dev/nvidiactl) and v4l2m2m requires /dev/video10 — mirroring the device check VAAPI already does. 'auto' falls back to software (libx264) when no usable device exists. Explicit FFMPEG_HW_ACCEL still forces a backend for non-standard setups. Added HwAccelTest::testGpuBackendChosenOnlyWhenDevicePresent locking the invariant. phpunit 442/887 green, PHPStan clean. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Symptom
On a server without an NVIDIA GPU, transcoding fails and the player shows "invalid video source / server unreachable." The stream log shows
hw=nvenc, and ffmpeg's error log:Root cause
detect_hw_encoder()inautomode pickednvencas soon asffmpeg -encoderslistedh264_nvenc— but that encoder is compiled into many ffmpeg builds regardless of hardware. So on a GPU-less host it chose nvenc, which then failed at runtime (nolibcuda.so.1). VAAPI already guarded on its device file; nvenc and v4l2m2m didn't.Fix
nvencnow requires a real device:/dev/nvidia0or/dev/nvidiactl.v4l2m2mnow requires/dev/video10and the encoder (was||).autocorrectly falls back to software (libx264) when no usable device exists.FFMPEG_HW_ACCEL=nvenc|vaapi|v4l2m2mstill forces a backend for non-standard setups (the override path is unchanged).Added
HwAccelTest::testGpuBackendChosenOnlyWhenDevicePresent— would have failed before this fix on the affected server.phpunit 442/887 green · PHPStan level 5 clean.
🤖 Generated with Claude Code