Fix doorbell-viewport display and ring detection

- Switch to sysfs backlight (drm backend) to avoid DRM plane reset on
  display power cycle caused by vcgencmd display_power
- Add udev rule and sysfs permissions for rpi_backlight
- Fix multi-packet WebSocket decoder (ring events were being dropped)
- Fix mpv loop/cache flags (--loop=no, bounded --demuxer-max-bytes)
- Remove hardware decode (caused SIGSEGV on RPi4 with fkms)

2 files changed, 19 insertions, 3 deletions

diff --git a/doorbell-viewport/files/doorbell-viewport.py b/doorbell-viewport/files/doorbell-viewport.py
index 3167671..2c5b50a 100644
--- a/doorbell-viewport/files/doorbell-viewport.py
+++ b/doorbell-viewport/files/doorbell-viewport.py
@@ -392,10 +392,9 @@ class DoorbellViewport:
             "--no-input-default-bindings",
             "--no-config",
             "--really-quiet",
-            "--loop=inf",
+            "--loop=no",
             "--cache=yes",
-            "--cache-secs=3",
-            "--demuxer-max-bytes=50M",
+            "--demuxer-max-bytes=1M",
             "--hwdec=no",
             self.config.rtsp_url,
         ]
diff --git a/doorbell-viewport/tasks/main.yaml b/doorbell-viewport/tasks/main.yaml
index 989111d..fa2b4da 100644
--- a/doorbell-viewport/tasks/main.yaml
+++ b/doorbell-viewport/tasks/main.yaml
@@ -10,6 +10,23 @@
     groups: "video,input,render"
     append: "yes"
 
+- name: allow doorbell-viewport user to control sysfs backlight
+  become: yes
+  copy:
+    dest: "/etc/udev/rules.d/99-doorbell-viewport-backlight.rules"
+    owner: "root"
+    group: "root"
+    mode: "0644"
+    content: |
+      SUBSYSTEM=="backlight", ACTION=="add", RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness", RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"
+
+- name: set backlight brightness writable by video group
+  become: yes
+  file:
+    path: "/sys/class/backlight/rpi_backlight/brightness"
+    group: "video"
+    mode: "0664"
+
 - name: apt install doorbell-viewport dependencies
   become: yes
   apt: name="{{item}}"