Hardware accelerated encoding using Intel QuickSync via VAAPI (#151)

* (nits)

* add hardware encoding support for Intel QSV via VAAPI

* automate RENDER_GID env var

.docker/base/add-render-group.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+# if no hwenc required, noop
+[[ -z "$NEKO_HWENC" ]] && exit 0
+
+if [[ -z "$RENDER_GID" ]]; then
+  RENDER_GID=$(stat -c "%g" /dev/dri/render* | tail -n 1)
+  # is /dev/dri passed to the container?
+  [[ -z "$RENDER_GID" ]] && exit 1
+fi
+
+# note that this could conceivably be a security risk...
+cnt_group=$(getent group "$RENDER_GID" | cut -d: -f1)
+if [[ -z "$cnt_group" ]]; then
+  groupadd -g "$RENDER_GID" nekorender
+  cnt_group=nekorender
+fi
+usermod -a -G "$cnt_group" "$USER"