Add Auto live view option with transcoding options (#24519)

* implement auto mode for single camera live view

* add transcoded live streams and stream ordering for auto mode

Cameras can now add lower quality live streams that go2rtc transcodes to H.264 on demand. `live.transcode` takes a source stream and a list of heights and bitrates, and each quality becomes a `{camera}_transcode_{height}p` stream. The config validator adds them to `live.streams` without moving any the user already placed, and drops them when transcoding is disabled or a height changes. `create_config.py` writes them into go2rtc's generated config at startup, and saving the config or deleting a camera syncs them through go2rtc's API, so no restart is needed. They use `#hardware`, so go2rtc picks a hardware encoder and falls back to the CPU when there isn't one.

The Live playback settings stream list can be reordered by drag, since its order is the auto ladder. Auto order sorts it by bitrate, measuring native streams through a new admin-only `/go2rtc/streams/{name}/bitrate` endpoint and using the configured bitrate for transcoded ones. A pure reorder wasn't saved before because RJSF, the settings form, and `update_yaml` all ignore map key order. Sections can now mark a map with `orderedMaps`, which sends the whole map with `replace_paths` so `config_set` rewrites it in order.

Transcoded streams aren't in `go2rtc.streams`, which only lists yaml streams, so the frontend treated them as not restreamed and fell back to jsmpeg. Every restream check now goes through `isRestreamedStream`.

Auto treated any stall with no bytes in the last 2 seconds as a dead camera and handed it to the error fallback, which went straight to jsmpeg. Heavy congestion can stop delivery completely, so congested viewers skipped every lower stream. Auto now declines only when stats show the camera offline, and a stall on a live camera steps down. The stream picker also has a Try highest quality button that sends auto back to the top stream.

* fixes

frigate/config/config.py

@@ -35,6 +35,12 @@ from frigate.util.config import (
     migrate_frigate_config,
 )
 from frigate.util.image import create_mask
+from frigate.util.live_streams import (
+    default_transcode_source,
+    is_transcode_stream_name,
+    transcode_stream_name,
+    transcode_streams,
+)
 from frigate.util.runtime_deps import sha256_of
 from frigate.util.services import auto_detect_hwaccel
 
@@ -283,11 +289,78 @@ def verify_config_roles(camera_config: CameraConfig) -> None:
         )
 
 
+def apply_live_transcode_streams(
+    frigate_config: FrigateConfig, camera_config: CameraConfig
+) -> None:
+    """Fold a camera's transcoded streams into its live stream list.
+
+    Enabled qualities missing from live.streams are appended, and entries the
+    user placed keep their position. Transcoded names that are no longer
+    generated are dropped unless they name a real go2rtc stream.
+    """
+    live = camera_config.live
+    transcode = live.transcode
+    go2rtc_streams = frigate_config.go2rtc.model_dump().get("streams") or {}
+    generated: dict[str, str] = {}
+
+    if transcode.enabled:
+        if transcode.source is None:
+            transcode.source = default_transcode_source(
+                camera_config.name, live.streams
+            )
+
+        if transcode.source not in go2rtc_streams:
+            raise ValueError(
+                f"Camera {camera_config.name} has transcoded streams enabled, but its source {transcode.source} is not a go2rtc stream."
+            )
+
+        generated = transcode_streams(
+            camera_config.name,
+            transcode.source,
+            [quality.model_dump() for quality in transcode.qualities],
+        )
+
+        for name in generated:
+            if name in go2rtc_streams:
+                raise ValueError(
+                    f"Camera {camera_config.name} generates transcoded stream {name}, which collides with a go2rtc stream of the same name."
+                )
+
+    streams = {
+        label: name
+        for label, name in live.streams.items()
+        if name in generated
+        or name in go2rtc_streams
+        or not is_transcode_stream_name(camera_config.name, name)
+    }
+    placed = set(streams.values())
+
+    for quality in transcode.qualities if transcode.enabled else []:
+        name = transcode_stream_name(camera_config.name, quality.height)
+
+        if name in placed:
+            continue
+
+        label = f"{quality.height}p"
+
+        if label in streams:
+            raise ValueError(
+                f"Camera {camera_config.name} already has a live stream named {label}; rename it or place the transcoded stream under another name."
+            )
+
+        streams[label] = name
+
+    live.streams = streams
+
+
 def verify_valid_live_stream_names(
     frigate_config: FrigateConfig, camera_config: CameraConfig
 ) -> ValueError | None:
     """Verify that a restream exists to use for live view."""
     for _, stream_name in camera_config.live.streams.items():
+        if is_transcode_stream_name(camera_config.name, stream_name):
+            continue
+
         if (
             stream_name
             not in frigate_config.go2rtc.model_dump().get("streams", {}).keys()
@@ -1055,6 +1128,8 @@ class FrigateConfig(FrigateBaseModel):
                 "face_recognition": ["enabled", "min_area"],
                 "lpr": ["enabled", "expire_time", "min_area", "enhancement"],
                 "audio_transcription": ["enabled", "live_enabled"],
+                # transcode is camera-level only
+                "live": ["streams", "height", "quality"],
             }
 
             for section in allowed_fields_map:
@@ -1287,6 +1362,8 @@ class FrigateConfig(FrigateBaseModel):
             if not camera_config.live.streams:
                 camera_config.live.streams = {name: name}
 
+            apply_live_transcode_streams(self, camera_config)
+
             # generate the ffmpeg commands
             camera_config.create_ffmpeg_cmds()
             self.cameras[name] = camera_config