feat: report playback position in AudioEvent

proto/decentraland/sdk/components/audio_event.proto

@@ -9,4 +9,13 @@ option (common.ecs_component_id) = 1105;
 message PBAudioEvent {
   common.MediaState state = 1;
   uint32 timestamp = 2;     // monotonic counter
+
+  // Playback position report, written while a source that set `PBAudioSource.report_playback_position`
+  // is playing, so scenes can align gameplay with the audio that is actually heard (the renderer starts a
+  // clip some milliseconds after being asked to, and `PBAudioSource.current_time` is a write-only seek).
+  // Left unset on state changes that carry no position, on sources that did not opt in, and on players
+  // that expose no position at all, such as live audio streams.
+  optional uint32 tick_number = 3;   // scene tick in which the report was taken, equals EngineInfo.tick_number
+  optional float current_offset = 4; // playback position of the clip in seconds at that tick
+  optional float clip_length = 5;    // total length of the clip in seconds, when known
 }

proto/decentraland/sdk/components/audio_source.proto

@@ -28,4 +28,10 @@ message PBAudioSource {
   string audio_clip_url = 5; // the clip path as given in the `files` array of the scene's manifest.
   optional float current_time = 6;  // specifies the current playback time of the clip in seconds (default: 0).
   optional bool global = 7; // whether the audio plays at constant volume across the scene.
+
+  // Whether the renderer should report this source's playback position in `PBAudioEvent` while it plays
+  // (default: false). Media state changes are reported either way; this only enables the position reports,
+  // which a renderer writes far more often. Scenes that align gameplay with the audio they can actually hear
+  // set it; scenes playing fire-and-forget sounds leave it unset and pay nothing.
+  optional bool report_playback_position = 8;
 }