player: auto-enable HW decode when VPU accessible — remove R36S_HW_DECODE opt-in gate

src/r36s_dlna_browser/player/gstreamer_backend.py

@@ -62,32 +62,16 @@ def _probe_hw_decoders(gst_module) -> list:
     """
     Probe for available hardware video decoder GStreamer elements.
 
-    Hardware decode (mppvideodec / V4L2) is only auto-selected when
-    R36S_HW_DECODE=1 is set in the environment.  By default the probe is a
-    no-op: software avdec_h264 (libav, NEON-optimised) remains preferred
-    because mppvideodec outputs NV12 which requires an additional software
-    NV12→BGRA conversion step that outweighs the decode speedup.
-
-    Set R36S_HW_DECODE=1 (e.g. in MatHacks.sh) to enable hardware decode with
-    zero-copy NV12→SDL upload via SDL_UpdateNVTexture.
+    Probe for hardware video decoder GStreamer elements and boost their rank
+    above avdec_h264 when a VPU device node is accessible, so decodebin picks
+    them automatically.  NV12 frames are uploaded zero-copy via
+    SDL_UpdateNVTexture so no software colourspace conversion is needed.
 
     Returns the list of element names whose rank was boosted.
     """
-    if os.environ.get("R36S_HW_DECODE", "0") != "1":
-        # Still probe and log availability so the user knows the plugin is
-        # installed, but do not boost rank.
-        if _vpu_device_accessible():
-            for name in _HW_DECODER_ELEMENTS:
-                if gst_module.ElementFactory.find(name) is not None:
-                    log.info(
-                        "HW decode: %s available (VPU accessible) — not auto-selected. "
-                        "Set R36S_HW_DECODE=1 to enable (experimental).", name
-                    )
-        return []
-
     if not _vpu_device_accessible():
         log.info(
-            "HW decode: R36S_HW_DECODE=1 but no accessible VPU device node — "
+            "HW decode: no accessible VPU device node — "
             "falling back to software decode. "
             "Run deploy/arkos/setup_hw_decode.sh as root to fix permissions."
         )
@@ -416,8 +400,7 @@ class GStreamerBackend(PlayerBackend):
         sink.set_property("drop", True)
         # Accept NV12 when hardware decode is active (avoids a software colourspace
         # conversion step); fall back to BGRA for the software-decode path.
-        hw_active = os.environ.get("R36S_HW_DECODE", "0") == "1"
-        if hw_active:
+        if self._hw_decoders:
             caps_str = "video/x-raw,format=NV12;video/x-raw,format=BGRA"
         else:
             caps_str = "video/x-raw,format=BGRA"