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diff --git a/third_party/libwebrtc/api/audio_codecs/audio_format.h b/third_party/libwebrtc/api/audio_codecs/audio_format.h
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+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_AUDIO_CODECS_AUDIO_FORMAT_H_
+#define API_AUDIO_CODECS_AUDIO_FORMAT_H_
+
+#include <stddef.h>
+
+#include <map>
+#include <string>
+
+#include "absl/strings/string_view.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/system/rtc_export.h"
+
+namespace webrtc {
+
+// SDP specification for a single audio codec.
+struct RTC_EXPORT SdpAudioFormat {
+  using Parameters = std::map<std::string, std::string>;
+
+  SdpAudioFormat(const SdpAudioFormat&);
+  SdpAudioFormat(SdpAudioFormat&&);
+  SdpAudioFormat(absl::string_view name, int clockrate_hz, size_t num_channels);
+  SdpAudioFormat(absl::string_view name,
+                 int clockrate_hz,
+                 size_t num_channels,
+                 const Parameters& param);
+  SdpAudioFormat(absl::string_view name,
+                 int clockrate_hz,
+                 size_t num_channels,
+                 Parameters&& param);
+  ~SdpAudioFormat();
+
+  // Returns true if this format is compatible with `o`. In SDP terminology:
+  // would it represent the same codec between an offer and an answer? As
+  // opposed to operator==, this method disregards codec parameters.
+  bool Matches(const SdpAudioFormat& o) const;
+
+  SdpAudioFormat& operator=(const SdpAudioFormat&);
+  SdpAudioFormat& operator=(SdpAudioFormat&&);
+
+  friend bool operator==(const SdpAudioFormat& a, const SdpAudioFormat& b);
+  friend bool operator!=(const SdpAudioFormat& a, const SdpAudioFormat& b) {
+    return !(a == b);
+  }
+
+  std::string name;
+  int clockrate_hz;
+  size_t num_channels;
+  Parameters parameters;
+};
+
+// Information about how an audio format is treated by the codec implementation.
+// Contains basic information, such as sample rate and number of channels, which
+// isn't uniformly presented by SDP. Also contains flags indicating support for
+// integrating with other parts of WebRTC, like external VAD and comfort noise
+// level calculation.
+//
+// To avoid API breakage, and make the code clearer, AudioCodecInfo should not
+// be directly initializable with any flags indicating optional support. If it
+// were, these initializers would break any time a new flag was added. It's also
+// more difficult to understand:
+//   AudioCodecInfo info{16000, 1, 32000, true, false, false, true, true};
+// than
+//   AudioCodecInfo info(16000, 1, 32000);
+//   info.allow_comfort_noise = true;
+//   info.future_flag_b = true;
+//   info.future_flag_c = true;
+struct AudioCodecInfo {
+  AudioCodecInfo(int sample_rate_hz, size_t num_channels, int bitrate_bps);
+  AudioCodecInfo(int sample_rate_hz,
+                 size_t num_channels,
+                 int default_bitrate_bps,
+                 int min_bitrate_bps,
+                 int max_bitrate_bps);
+  AudioCodecInfo(const AudioCodecInfo& b) = default;
+  ~AudioCodecInfo() = default;
+
+  bool operator==(const AudioCodecInfo& b) const {
+    return sample_rate_hz == b.sample_rate_hz &&
+           num_channels == b.num_channels &&
+           default_bitrate_bps == b.default_bitrate_bps &&
+           min_bitrate_bps == b.min_bitrate_bps &&
+           max_bitrate_bps == b.max_bitrate_bps &&
+           allow_comfort_noise == b.allow_comfort_noise &&
+           supports_network_adaption == b.supports_network_adaption;
+  }
+
+  bool operator!=(const AudioCodecInfo& b) const { return !(*this == b); }
+
+  bool HasFixedBitrate() const {
+    RTC_DCHECK_GE(min_bitrate_bps, 0);
+    RTC_DCHECK_LE(min_bitrate_bps, default_bitrate_bps);
+    RTC_DCHECK_GE(max_bitrate_bps, default_bitrate_bps);
+    return min_bitrate_bps == max_bitrate_bps;
+  }
+
+  int sample_rate_hz;
+  size_t num_channels;
+  int default_bitrate_bps;
+  int min_bitrate_bps;
+  int max_bitrate_bps;
+
+  bool allow_comfort_noise = true;  // This codec can be used with an external
+                                    // comfort noise generator.
+  bool supports_network_adaption = false;  // This codec can adapt to varying
+                                           // network conditions.
+};
+
+// AudioCodecSpec ties an audio format to specific information about the codec
+// and its implementation.
+struct AudioCodecSpec {
+  bool operator==(const AudioCodecSpec& b) const {
+    return format == b.format && info == b.info;
+  }
+
+  bool operator!=(const AudioCodecSpec& b) const { return !(*this == b); }
+
+  SdpAudioFormat format;
+  AudioCodecInfo info;
+};
+
+}  // namespace webrtc
+
+#endif  // API_AUDIO_CODECS_AUDIO_FORMAT_H_