Address review: the capture ffmpeg had no -b:v, so it encoded at nvenc's
low default (~2.47 Mbps) and the library then re-encoded to 8 Mbps, which
only upscaled already-lost detail. The double encode also kept CPU decode
+ scale + re-encode in the library, contradicting the "GPU handles it"
claim.
Now the system ffmpeg produces the final Discord-ready H264 in one pass
(-b:v/-maxrate at the configured bitrate, -bf 0, 1s keyframes, yuv420p,
-forced-idr) and prepareStream uses noTranscoding:true to remux only. One
GPU encode, no library decode/scale/re-encode.
Verified locally: high-motion source fills 8.7 Mbps at these args (vs the
~2.47 Mbps no-bitrate default), real :1 desktop holds 60fps at realtime,
and the capture -> copy/remux chain yields h264 1920x1080 yuv420p 60fps
has_b_frames=0. tsc --noEmit passes. Live Discord test pending reboot.
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