"Auto" hwdec uses wrong hw decoder module on optimus machines
By defaut vlc uses Automatic for hardware accelerated decoding. On an nvidia optimus machine where nvidia drivers are not installed vlc picks vdpau instead of one of the vaapi outs. The result is very poor playback, at least with h264. Attached message log from vlc at fresh install defaults & one with the hwdec changed to one of the vaapi choices, this case x11
Notable - Default (playback is terrible, large # dropped frames avcodec debug: available hardware decoder output format 109 (vdpau) avcodec debug: available hardware decoder output format 53 (vaapi_vld) avcodec debug: available software decoder output format 0 (yuv420p) core debug: looking for hw decoder module matching "any": 4 candidates
core debug: using hw decoder module "vdpau_avcodec"
Specified (playback is fine avcodec debug: available hardware decoder output format 109 (vdpau) avcodec debug: available hardware decoder output format 53 (vaapi_vld) avcodec debug: available software decoder output format 0 (yuv420p) core debug: looking for hw decoder module matching "vaapi_x11": 4 candidates
core debug: using hw decoder module "vaapi_x11"