[feat] negotiate per-device preview and audio subscriptions

2026-10-19 10:23:10 +08:00 · 2026-10-12 03:07:10 +08:00
parent c9e0078bfb
commit c8907a00f9
10 changed files with 251 additions and 3 deletions
@@ -0,0 +1,78 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-10-12
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _PREVIEW_SUBSCRIPTIONS_H_
+#define _PREVIEW_SUBSCRIPTIONS_H_
+
+#include <preview_subscription.h>
+
+#include <chrono>
+#include <mutex>
+#include <string>
+#include <unordered_map>
+
+namespace crossdesk {
+// Accessed by the network callback and screen-capture callback. Legacy
+// controllers have no entry and continue receiving their normal stream.
+class PreviewSubscriptions {
+public:
+  using Clock = std::chrono::steady_clock;
+  bool IsNewer(const std::string &id, uint32_t request_id) {
+    std::lock_guard lock(mutex_);
+    const auto found = states_.find(id);
+    return found == states_.end() ||
+           request_id > found->second.request.request_id;
+  }
+  bool Set(const std::string &id, const PreviewSubscription &request) {
+    std::lock_guard lock(mutex_);
+    auto &state = states_[id];
+    if (request.request_id <= state.request.request_id)
+      return false;
+    state.request = request;
+    state.next.clear();
+    return true;
+  }
+  bool ShouldSend(const std::string &id, Clock::time_point now = Clock::now(),
+                  const std::string &stream = {}) {
+    std::lock_guard lock(mutex_);
+    const auto found = states_.find(id);
+    if (found == states_.end())
+      return true;
+    auto &state = found->second;
+    if (!state.request.fps)
+      return false;
+    // Interactive streams use the encoder's own 30/60 FPS cadence. A second
+    // time gate here can drop valid frames because capture timing varies.
+    if (state.request.fps == 60)
+      return true;
+    auto &next = state.next[stream];
+    if (now < next)
+      return false;
+    next = now + std::chrono::milliseconds(1000 / state.request.fps);
+    return true;
+  }
+  bool ShouldSendAudio(const std::string &id) {
+    std::lock_guard lock(mutex_);
+    const auto found = states_.find(id);
+    return found == states_.end() || found->second.request.audio;
+  }
+  void Remove(const std::string &id) {
+    std::lock_guard lock(mutex_);
+    states_.erase(id);
+  }
+
+private:
+  struct State {
+    PreviewSubscription request;
+    // One display must not consume another display's preview frame budget.
+    std::unordered_map<std::string, Clock::time_point> next;
+  };
+  std::mutex mutex_;
+  std::unordered_map<std::string, State> states_;
+};
+} // namespace crossdesk
+
+#endif