Implement Cast Streaming mirroring, DLNA casting, daemon+GUI, and breadd integration

Builds out the full v1 scope: a vendored+patched openscreen subset for
low-latency Cast Streaming (Mirroring receiver 0F5096E8) alongside the
existing Cast V2/HLS and new DLNA/AVTransport casting paths, breadcastd's
Idle/Casting state machine with a private IPC socket, the breadcast GTK4
popup as a thin IPC client, and bread.cast.*/bread.command.cast.* breadd
integration (device discovery, start/stop, mirroring lifecycle events).
Also adds bakery/systemd/Forgejo CI packaging.

Validated end-to-end against a real Chromecast/Google TV: negotiated
Cast Streaming session, live pipeline playback, and daemon+GUI click-to-cast/
stop through the actual popup.

breadcast-caststream-sys/vendor/openscreen/cast/streaming/rtp_time.h

@@ -0,0 +1,257 @@
+// Copyright 2015 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CAST_STREAMING_RTP_TIME_H_
+#define CAST_STREAMING_RTP_TIME_H_
+
+#include <stdint.h>
+
+#include <chrono>
+#include <cmath>
+#include <limits>
+#include <sstream>
+#include <type_traits>
+
+#include "cast/streaming/impl/expanded_value_base.h"
+#include "platform/api/time.h"
+#include "util/saturate_cast.h"
+
+namespace openscreen::cast {
+
+// Forward declarations (see below).
+class RtpTimeDelta;
+class RtpTimeTicks;
+
+// Convenience operator overloads for logging.
+std::ostream& operator<<(std::ostream& out, const RtpTimeDelta rhs);
+std::ostream& operator<<(std::ostream& out, const RtpTimeTicks rhs);
+
+// The difference between two RtpTimeTicks values.  This data type is modeled
+// off of Chromium's base::TimeDelta, and used for performing compiler-checked
+// arithmetic with RtpTimeTicks.
+//
+// This data type wraps a value, providing only the meaningful set of math
+// operations that may be performed on the value.  RtpTimeDeltas may be
+// added/subtracted with other RtpTimeDeltas to produce a RtpTimeDelta holding
+// the sum/difference.  RtpTimeDeltas may also be multiplied or divided by
+// integer amounts.  Finally, RtpTimeDeltas may be divided by other
+// RtpTimeDeltas to compute a number of periods (trunc'ed to an integer), or
+// modulo each other to determine a time period remainder.
+//
+// The base class provides bit truncation/extension features for
+// wire-formatting, and also the comparison operators.
+//
+// Usage example:
+//
+//   // Time math.
+//   RtpTimeDelta zero;
+//   RtpTimeDelta one_second_later =
+//       zero + RtpTimeDelta::FromTicks(kAudioSamplingRate);
+//   RtpTimeDelta ten_seconds_later = one_second_later * 10;
+//   int64_t ten_periods = ten_seconds_later / one_second_later;
+//
+//   // Logging convenience.
+//   OSP_DLOG_INFO << "The RTP time offset is " << ten_seconds_later;
+//
+//   // Convert (approximately!) between RTP timebase and microsecond timebase:
+//   RtpTimeDelta nine_seconds_in_rtp = ten_seconds_later - one_second_later;
+//   using std::chrono::microseconds;
+//   microseconds nine_seconds_duration =
+//       nine_seconds_in_rtp.ToDuration<microseconds>(kAudioSamplingRate);
+//   RtpTimeDelta two_seconds_in_rtp =
+//       RtpTimeDelta::FromDuration(std::chrono::seconds(2),
+//                                  kAudioSamplingRate);
+class RtpTimeDelta : public ExpandedValueBase<int64_t, RtpTimeDelta> {
+ public:
+  constexpr RtpTimeDelta() : ExpandedValueBase(0) {}
+
+  // Arithmetic operators (with other deltas).
+  constexpr RtpTimeDelta operator+(RtpTimeDelta rhs) const {
+    return RtpTimeDelta(value_ + rhs.value_);
+  }
+  constexpr RtpTimeDelta operator-(RtpTimeDelta rhs) const {
+    return RtpTimeDelta(value_ - rhs.value_);
+  }
+  constexpr RtpTimeDelta& operator+=(RtpTimeDelta rhs) {
+    return (*this = (*this + rhs));
+  }
+  constexpr RtpTimeDelta& operator-=(RtpTimeDelta rhs) {
+    return (*this = (*this - rhs));
+  }
+  constexpr RtpTimeDelta operator-() const { return RtpTimeDelta(-value_); }
+
+  // Multiplicative operators (with other deltas).
+  constexpr int64_t operator/(RtpTimeDelta rhs) const {
+    return value_ / rhs.value_;
+  }
+  constexpr RtpTimeDelta operator%(RtpTimeDelta rhs) const {
+    return RtpTimeDelta(value_ % rhs.value_);
+  }
+  constexpr RtpTimeDelta& operator%=(RtpTimeDelta rhs) {
+    return (*this = (*this % rhs));
+  }
+
+  // Multiplicative operators (with integer types).
+  template <typename IntType>
+  constexpr RtpTimeDelta operator*(IntType rhs) const {
+    static_assert(std::numeric_limits<IntType>::is_integer,
+                  "|rhs| must be a POD integer type");
+    return RtpTimeDelta(value_ * rhs);
+  }
+  template <typename IntType>
+  constexpr RtpTimeDelta operator/(IntType rhs) const {
+    static_assert(std::numeric_limits<IntType>::is_integer,
+                  "|rhs| must be a POD integer type");
+    return RtpTimeDelta(value_ / rhs);
+  }
+  template <typename IntType>
+  constexpr RtpTimeDelta& operator*=(IntType rhs) {
+    return (*this = (*this * rhs));
+  }
+  template <typename IntType>
+  constexpr RtpTimeDelta& operator/=(IntType rhs) {
+    return (*this = (*this / rhs));
+  }
+
+  // Maps this RtpTimeDelta to an approximate std::chrono::duration using the
+  // given RTP timebase.  Assumes a zero-valued Duration corresponds to a
+  // zero-valued RtpTimeDelta.
+  template <typename Duration>
+  Duration ToDuration(int rtp_timebase) const {
+    OSP_CHECK_GT(rtp_timebase, 0);
+    constexpr Duration kOneSecond =
+        std::chrono::duration_cast<Duration>(std::chrono::seconds(1));
+    return Duration(ToNearestRepresentativeValue<typename Duration::rep>(
+        static_cast<double>(value_) / rtp_timebase * kOneSecond.count()));
+  }
+
+  // Maps the `duration` to an approximate RtpTimeDelta using the given RTP
+  // timebase.  Assumes a zero-valued Duration corresponds to a zero-valued
+  // RtpTimeDelta.
+  template <typename Duration>
+  static constexpr RtpTimeDelta FromDuration(Duration duration,
+                                             int rtp_timebase) {
+    constexpr Duration kOneSecond =
+        std::chrono::duration_cast<Duration>(std::chrono::seconds(1));
+    static_assert(kOneSecond > Duration::zero(),
+                  "Duration is too coarse-grained to represent one second.");
+    return RtpTimeDelta(ToNearestRepresentativeValue<int64_t>(
+        static_cast<double>(duration.count()) / kOneSecond.count() *
+        rtp_timebase));
+  }
+
+  // Construct a RtpTimeDelta from an exact number of ticks.
+  static constexpr RtpTimeDelta FromTicks(int64_t ticks) {
+    return RtpTimeDelta(ticks);
+  }
+
+ private:
+  friend class ExpandedValueBase<int64_t, RtpTimeDelta>;
+  friend class RtpTimeTicks;
+  friend std::ostream& operator<<(std::ostream& out, const RtpTimeDelta rhs);
+
+  constexpr explicit RtpTimeDelta(int64_t ticks) : ExpandedValueBase(ticks) {}
+
+  constexpr int64_t value() const { return value_; }
+
+  template <typename Rep>
+  static std::enable_if_t<std::is_floating_point<Rep>::value, Rep>
+  ToNearestRepresentativeValue(double ticks) {
+    return Rep(ticks);
+  }
+
+  template <typename Rep>
+  static std::enable_if_t<std::is_integral<Rep>::value, Rep>
+  ToNearestRepresentativeValue(double ticks) {
+    return rounded_saturate_cast<Rep>(ticks);
+  }
+};
+
+// A media timestamp whose timebase matches the periodicity of the content
+// (e.g., for audio, the timebase would be the sampling frequency).  This data
+// type is modeled off of Chromium's base::TimeTicks.
+//
+// This data type wraps a value, providing only the meaningful set of math
+// operations that may be performed on the value.  The difference between two
+// RtpTimeTicks is a RtpTimeDelta.  Likewise, adding or subtracting a
+// RtpTimeTicks with a RtpTimeDelta produces an off-set RtpTimeTicks.
+//
+// The base class provides bit truncation/extension features for
+// wire-formatting, and also the comparison operators.
+//
+// Usage example:
+//
+//   // Time math.
+//   RtpTimeTicks origin;
+//   RtpTimeTicks at_one_second =
+//       origin + RtpTimeDelta::FromTicks(kAudioSamplingRate);
+//   RtpTimeTicks at_two_seconds =
+//       at_one_second + RtpTimeDelta::FromTicks(kAudioSamplingRate);
+//   RtpTimeDelta elasped_in_between = at_two_seconds - at_one_second;
+//   RtpTimeDelta thrice_as_much_elasped = elasped_in_between * 3;
+//   RtpTimeTicks at_four_seconds = at_one_second + thrice_as_much_elasped;
+//
+//   // Logging convenience.
+//   OSP_DLOG_INFO << "The RTP timestamp is " << at_four_seconds;
+//
+//   // Convert (approximately!) between RTP timebase and stream time offsets in
+//   // microsecond timebase:
+//   using std::chrono::microseconds;
+//   microseconds four_seconds_since_stream_start =
+//       at_four_seconds.ToTimeSinceOrigin<microseconds>(kAudioSamplingRate);
+//   RtpTimeTicks at_three_seconds = RtpTimeDelta::FromTimeSinceOrigin(
+//       std::chrono::seconds(3), kAudioSamplingRate);
+class RtpTimeTicks : public ExpandedValueBase<int64_t, RtpTimeTicks> {
+ public:
+  constexpr explicit RtpTimeTicks(int64_t value) : ExpandedValueBase(value) {}
+  constexpr RtpTimeTicks() : ExpandedValueBase(0) {}
+
+  constexpr int64_t value() const { return value_; }
+
+  // Compute the difference between two RtpTimeTickses.
+  constexpr RtpTimeDelta operator-(RtpTimeTicks rhs) const {
+    return RtpTimeDelta(value_ - rhs.value_);
+  }
+
+  // Return a new RtpTimeTicks before or after this one.
+  constexpr RtpTimeTicks operator+(RtpTimeDelta rhs) const {
+    return RtpTimeTicks(value_ + rhs.value());
+  }
+  constexpr RtpTimeTicks operator-(RtpTimeDelta rhs) const {
+    return RtpTimeTicks(value_ - rhs.value());
+  }
+  constexpr RtpTimeTicks& operator+=(RtpTimeDelta rhs) {
+    return (*this = (*this + rhs));
+  }
+  constexpr RtpTimeTicks& operator-=(RtpTimeDelta rhs) {
+    return (*this = (*this - rhs));
+  }
+
+  // Maps this RtpTimeTicks to an approximate std::chrono::duration representing
+  // the amount of time since the origin point (e.g., the start of a stream)
+  // using the given `rtp_timebase`.  Assumes a zero-valued Duration corresponds
+  // to a zero-valued RtpTimeTicks.
+  template <typename Duration>
+  Duration ToTimeSinceOrigin(int rtp_timebase) const {
+    return (*this - RtpTimeTicks()).ToDuration<Duration>(rtp_timebase);
+  }
+
+  // Maps the `time_since_origin` to an approximate RtpTimeTicks using the given
+  // RTP timebase.  Assumes a zero-valued Duration corresponds to a zero-valued
+  // RtpTimeTicks.
+  template <typename Duration>
+  static constexpr RtpTimeTicks FromTimeSinceOrigin(Duration time_since_origin,
+                                                    int rtp_timebase) {
+    return RtpTimeTicks() +
+           RtpTimeDelta::FromDuration(time_since_origin, rtp_timebase);
+  }
+
+ private:
+  friend class ExpandedValueBase<int64_t, RtpTimeTicks>;
+  friend std::ostream& operator<<(std::ostream& out, const RtpTimeTicks rhs);
+};
+
+}  // namespace openscreen::cast
+
+#endif  // CAST_STREAMING_RTP_TIME_H_