Adding C++ versions of currently spec'd "RtpParameters" structs.

webrtc/api/rtpparameters.h

Index: webrtc/api/rtpparameters.h
diff --git a/webrtc/api/rtpparameters.h b/webrtc/api/rtpparameters.h
index 13704dc15b0e6d41d5b532d7dcc80bae3cc2c996..f506c4031c3eacf6e923f3cea67d6f2f9586c4ee 100644
--- a/webrtc/api/rtpparameters.h
+++ b/webrtc/api/rtpparameters.h
@@ -12,22 +12,297 @@
 #define WEBRTC_API_RTPPARAMETERS_H_
 
 #include <string>
+#include <unordered_map>
 #include <vector>
 
+#include "webrtc/api/mediatypes.h"
 #include "webrtc/base/optional.h"
 
 namespace webrtc {
 
-// These structures are defined as part of the RtpSender interface.
-// See http://w3c.github.io/webrtc-pc/#rtcrtpsender-interface for details.
+// These structures are intended to mirror those defined by:
+// http://draft.ortc.org/#rtcrtpdictionaries*
+// Contains everything specified as of 2017 Jan 24.
+//
+// They are used when retrieving or modifying the parameters of an
+// RtpSender/RtpReceiver, or retrieving capabilities.
+//
+// Note on conventions: Where ORTC may use "octet", "short" and "unsigned"
+// types, we typically use "int", in keeping with our style guidelines. The
+// parameter's actual valid range will be enforced when the parameters are set,
+// rather than when the parameters struct is built. An exception is made for
+// SSRCs, since they use the full unsigned 32-bit range, and aren't expected to
+// be used for any numeric comparisons/operations.
+//
+// Additionally, where ORTC uses strings, we may use enums for things that have
+// a fixed number of supported values. However, for things that can be extended
+// (such as codecs, by providing an external encoder factory), a string
+// identifier is used.
+
+enum class FecMechanism {
+  RED,
+  RED_AND_ULPFEC,
+  FLEXFEC,
+};
+
+// Used in RtcpFeedback struct.
+enum class RtcpFeedbackType {
+  ACK,
+  CCM,
+  NACK,
+  REMB,  // "goog-remb"
+  TRANSPORT_CC,
+};
+
+// Used in RtcpFeedback struct when type is ACK, NACK or CCM.
+enum class RtcpFeedbackMessageType {
+  // Equivalent to {type: "nack", parameter: undefined} in ORTC.
+  GENERIC_NACK,
+  PLI,  // Usable with NACK.
+  FIR,  // Usable with CCM.
+};
+
+enum class DtxStatus {
+  DISABLED,
+  ENABLED,
+};
+
+enum class DegradationPreference {
+  MAINTAIN_FRAMERATE,
+  MAINTAIN_RESOLUTION,
+  BALANCED,
+};
+
+enum class PriorityType { VERY_LOW, LOW, MEDIUM, HIGH };
+
+struct RtcpFeedback {
+  RtcpFeedbackType type = RtcpFeedbackType::ACK;
+
+  // Equivalent to ORTC "parameter" field with slight differences:
+  // 1. It's an enum instead of a string.
+  // 2. Generic NACK feedback is represented by a GENERIC_NACK message type,
+  //    rather than an unset "parameter" value.
+  rtc::Optional<RtcpFeedbackMessageType> message_type;
+
+  bool operator==(const RtcpFeedback& o) const {
+    return type == o.type && message_type == o.message_type;
+  }
+  bool operator!=(const RtcpFeedback& o) const { return !(*this == o); }
+};
+
+// RtpCodecCapability is to RtpCodecParameters as RtpCapabilities is to
+// RtpParameters. This represents the static capabilities of an endpoint's
+// implementation of a codec.
+struct RtpCodecCapability {
+  // Build MIME "type/subtype" string from |name| and |kind|.
+  std::string mime_type() const { return MediaTypeToString(kind) + "/" + name; }
+
+  // Used to identify the codec. Equivalent to MIME subtype.
+  std::string name;
+
+  // The media type of this codec. Equivalent to MIME top-level type.
+  cricket::MediaType kind = cricket::MEDIA_TYPE_AUDIO;
+
+  // Clock rate in Hertz. If unset, the codec is applicable to any clock rate.
+  rtc::Optional<int> clock_rate;
+
+  // Default payload type for this codec. Mainly needed for codecs that use
+  // that have statically assigned payload types.
+  rtc::Optional<int> preferred_payload_type;
+
+  // Maximum packetization time supported by an RtpReceiver for this codec.
+  // TODO(deadbeef): Not implemented.
+  rtc::Optional<int> max_ptime;
+
+  // Preferred packetization time for an RtpReceiver or RtpSender of this
+  // codec.
+  // TODO(deadbeef): Not implemented.
+  rtc::Optional<int> ptime;
+
+  // The number of audio channels supported. Unused for video codecs.
+  rtc::Optional<int> num_channels;
+
+  // Feedback mechanisms supported for this codec.
+  std::vector<RtcpFeedback> rtcp_feedback;
+
+  // Codec-specific parameters that must be signaled to the remote party.
+  // Corresponds to "a=fmtp" parameters in SDP.
+  std::unordered_map<std::string, std::string> parameters;
+
+  // Codec-specific parameters that may optionally be signaled to the remote
+  // party.
+  // TODO(deadbeef): Not implemented.
+  std::unordered_map<std::string, std::string> options;
+
+  // Maximum number of temporal layer extensions supported by this codec.
+  // For example, a value of 1 indicates that 2 total layers are supported.
+  // TODO(deadbeef): Not implemented.
+  int max_temporal_layer_extensions = 0;
+
+  // Maximum number of spatial layer extensions supported by this codec.
+  // For example, a value of 1 indicates that 2 total layers are supported.
+  // TODO(deadbeef): Not implemented.
+  int max_spatial_layer_extensions = 0;
+
+  // Whether the implementation can send/receive SVC layers with distinct
+  // SSRCs. Always false for audio codecs. True for video codecs that support
+  // scalable video coding with MRST.
+  // TODO(deadbeef): Not implemented.
+  bool svc_multi_stream_support = false;
+
+  bool operator==(const RtpCodecCapability& o) const {
+    return name == o.name && kind == o.kind && clock_rate == o.clock_rate &&
+           preferred_payload_type == o.preferred_payload_type &&
+           max_ptime == o.max_ptime && ptime == o.ptime &&
+           num_channels == o.num_channels && rtcp_feedback == o.rtcp_feedback &&
+           parameters == o.parameters && options == o.options &&
+           max_temporal_layer_extensions == o.max_temporal_layer_extensions &&
+           max_spatial_layer_extensions == o.max_spatial_layer_extensions &&
+           svc_multi_stream_support == o.svc_multi_stream_support;
+  }
+  bool operator!=(const RtpCodecCapability& o) const { return !(*this == o); }
+};
+
+// Used in RtpCapabilities; represents the capabilities/preferences of an
+// implementation for a header extension.
+//
+// Just called "RtpHeaderExtension" in ORTC, but the "Capability" suffix was
+// added here for consistency and to avoid confusion with
+// RtpHeaderExtensionParameters.
+//
+// Note that ORTC includes a "kind" field, but we omit this because it's
+// redundant; if you call "RtpReceiver::GetCapabilities(MEDIA_TYPE_AUDIO)",
+// you know you're getting audio capabilities.
+struct RtpHeaderExtensionCapability {
+  // URI of this extension, as defined in RFC5285.
+  std::string uri;
+
+  // Preferred value of ID that goes in the packet.
+  rtc::Optional<int> preferred_id;
+
+  // If true, it's preferred that the value in the header is encrypted.
+  // TODO(deadbeef): Not implemented.
+  bool preferred_encrypt = false;
+
+  bool operator==(const RtpHeaderExtensionCapability& o) const {
+    return uri == o.uri && preferred_id == o.preferred_id &&
+           preferred_encrypt == o.preferred_encrypt;
+  }
+  bool operator!=(const RtpHeaderExtensionCapability& o) const {
+    return !(*this == o);
+  }
+};
+
+// Used in RtpParameters; represents a specific configuration of a header
+// extension.
+struct RtpHeaderExtensionParameters {
+  // URI of this extension, as defined in RFC5285.
+  std::string uri;
+
+  // ID value that goes in the packet.
+  int id = 0;
+
+  // If true, the value in the header is encrypted.
+  // TODO(deadbeef): Not implemented.
+  bool encrypt = false;
+
+  bool operator==(const RtpHeaderExtensionParameters& o) const {
+    return uri == o.uri && id == o.id && encrypt == o.encrypt;
+  }
+  bool operator!=(const RtpHeaderExtensionParameters& o) const {
+    return !(*this == o);
+  }
+};
+
+struct RtpFecParameters {
+  // If unset, a value is chosen by the implementation.
+  rtc::Optional<uint32_t> ssrc;
+
+  FecMechanism mechanism = FecMechanism::RED;
+
+  bool operator==(const RtpFecParameters& o) const {
+    return ssrc == o.ssrc && mechanism == o.mechanism;
+  }
+  bool operator!=(const RtpFecParameters& o) const { return !(*this == o); }
+};
+
+struct RtpRtxParameters {
+  // If unset, a value is chosen by the implementation.
+  rtc::Optional<uint32_t> ssrc;
+
+  bool operator==(const RtpRtxParameters& o) const { return ssrc == o.ssrc; }
+  bool operator!=(const RtpRtxParameters& o) const { return !(*this == o); }
+};
+
 struct RtpEncodingParameters {
+  // If unset, a value is chosen by the implementation.
   rtc::Optional<uint32_t> ssrc;
+
+  // Can be used to reference a codec in the |codecs| member of the
+  // RtpParameters that contains this RtpEncodingParameters. If unset, the
+  // implementation will choose the first possible codec.
+  // TODO(deadbeef): Not implemented.
+  rtc::Optional<int> codec_payload_type;
+
+  // Specifies the FEC mechanism, if set.
+  // TODO(deadbeef): Not implemented.
+  rtc::Optional<RtpFecParameters> fec;
+
+  // Specifies the RTX parameters, if set.
+  // TODO(deadbeef): Not implemented.
+  rtc::Optional<RtpRtxParameters> rtx;
+
+  // Only used for audio. If set, determines whether or not discontinuous
+  // transmission will be used, if an available codec supports it. If not
+  // set, the implementation default setting will be used.
+  rtc::Optional<DtxStatus> dtx;
+
+  // The relative priority of this encoding.
+  // TODO(deadbeef): Not implemented.
+  rtc::Optional<PriorityType> priority;
+
+  // If set, this represents the Transport Independent Application Specific
+  // maximum bandwidth defined in RFC3890. If unset, there is no maximum
+  // bitrate.
+  // Just called "maxBitrate" in ORTC spec.
+  rtc::Optional<int> max_bitrate_bps;
+
+  // TODO(deadbeef): Not implemented.
+  rtc::Optional<int> max_framerate;
+
+  // For video, scale the resolution down by this factor.
+  // TODO(deadbeef): Not implemented.
+  double scale_resolution_down_by = 1.0;
+
+  // Scale the framerate down by this factor.
+  // TODO(deadbeef): Not implemented.
+  double scale_framerate_down_by = 1.0;
+
+  // For an RtpSender, set to true to cause this encoding to be sent, and false
+  // for it not to be sent. For an RtpReceiver, set to true to cause the
+  // encoding to be decoded, and false for it to be ignored.
+  // TODO(deadbeef): RtpReceiver part is not implemented.
   bool active = true;
-  int max_bitrate_bps = -1;
+
+  // Value to use for RID RTP header extension.
+  // Called "encodingId" in ORTC.
+  // TODO(deadbeef): Not implemented.
+  std::string rid;
+
+  // RIDs of encodings on which this layer depends.
+  // Called "dependencyEncodingIds" in ORTC spec.
+  // TODO(deadbeef): Not implemented.
+  std::vector<std::string> dependency_rids;
 
   bool operator==(const RtpEncodingParameters& o) const {
-    return ssrc == o.ssrc && active == o.active &&
-           max_bitrate_bps == o.max_bitrate_bps;
+    return ssrc == o.ssrc && codec_payload_type == o.codec_payload_type &&
+           fec == o.fec && rtx == o.rtx && dtx == o.dtx &&
+           priority == o.priority && max_bitrate_bps == o.max_bitrate_bps &&
+           max_framerate == o.max_framerate &&
+           scale_resolution_down_by == o.scale_resolution_down_by &&
+           scale_framerate_down_by == o.scale_framerate_down_by &&
+           active == o.active && rid == o.rid &&
+           dependency_rids == o.dependency_rids;
   }
   bool operator!=(const RtpEncodingParameters& o) const {
     return !(*this == o);
@@ -35,25 +310,107 @@ struct RtpEncodingParameters {
 };
 
 struct RtpCodecParameters {
-  int payload_type;
-  std::string mime_type;
-  int clock_rate;
-  int channels = 1;
-  // TODO(deadbeef): Add sdpFmtpLine field.
+  // Build MIME "type/subtype" string from |name| and |kind|.
+  std::string mime_type() const { return MediaTypeToString(kind) + "/" + name; }
+
+  // Used to identify the codec. Equivalent to MIME subtype.
+  std::string name;
+
+  // The media type of this codec. Equivalent to MIME top-level type.
+  cricket::MediaType kind = cricket::MEDIA_TYPE_AUDIO;
+
+  // Payload type used to identify this codec in RTP packets.
+  // This MUST always be present, and must be unique across all codecs using
+  // the same transport.
+  int payload_type = 0;
+
+  // If unset, the implementation default is used.
+  rtc::Optional<int> clock_rate;
+
+  // The number of audio channels used. Unset for video codecs. If unset for
+  // audio, the implementation default is used.
+  // TODO(deadbeef): The "implementation default" part is unimplemented.
+  rtc::Optional<int> num_channels;
+
+  // The maximum packetization time to be used by an RtpSender.
+  // If |ptime| is also set, this will be ignored.
+  // TODO(deadbeef): Not implemented.
+  rtc::Optional<int> max_ptime;
+
+  // The packetization time to be used by an RtpSender.
+  // If unset, will use any time up to max_ptime.
+  // TODO(deadbeef): Not implemented.
+  rtc::Optional<int> ptime;
+
+  // Feedback mechanisms to be used for this codec.
+  // TODO(deadbeef): Not implemented.
+  std::vector<RtcpFeedback> rtcp_feedback;
+
+  // Codec-specific parameters that must be signaled to the remote party.
+  // Corresponds to "a=fmtp" parameters in SDP.
+  // TODO(deadbeef): Not implemented.
+  std::unordered_map<std::string, std::string> parameters;
 
   bool operator==(const RtpCodecParameters& o) const {
-    return payload_type == o.payload_type && mime_type == o.mime_type &&
-           clock_rate == o.clock_rate && channels == o.channels;
+    return name == o.name && kind == o.kind && payload_type == o.payload_type &&
+           clock_rate == o.clock_rate && num_channels == o.num_channels &&
+           max_ptime == o.max_ptime && ptime == o.ptime &&
+           rtcp_feedback == o.rtcp_feedback && parameters == o.parameters;
   }
   bool operator!=(const RtpCodecParameters& o) const { return !(*this == o); }
 };
 
+// RtpCapabilities is used to represent the static capabilities of an
+// endpoint. An application can use these capabilities to construct an
+// RtpParameters.
+struct RtpCapabilities {
+  // Supported codecs.
+  std::vector<RtpCodecCapability> codecs;
+
+  // Supported RTP header extensions.
+  std::vector<RtpHeaderExtensionCapability> header_extensions;
+
+  // Supported Forward Error Correction (FEC) mechanisms.
+  std::vector<FecMechanism> fec;
+
+  bool operator==(const RtpCapabilities& o) const {
+    return codecs == o.codecs && header_extensions == o.header_extensions &&
+           fec == o.fec;
+  }
+  bool operator!=(const RtpCapabilities& o) const { return !(*this == o); }
+};
+
+// Note that unlike in ORTC, an RtcpParameters is not included in
+// RtpParameters, because our API will include an additional "RtpTransport"
+// abstraction on which RTCP parameters are set.
 struct RtpParameters {
-  std::vector<RtpEncodingParameters> encodings;
+  // Used when calling getParameters/setParameters with a PeerConnection
+  // RtpSender, to ensure that outdated parameters are not unintentionally
+  // applied successfully.
+  // TODO(deadbeef): Not implemented.
+  std::string transaction_id;
+
+  // Value to use for MID RTP header extension.
+  // Called "muxId" in ORTC.
+  // TODO(deadbeef): Not implemented.
+  std::string mid;
+
   std::vector<RtpCodecParameters> codecs;
 
+  // TODO(deadbeef): Not implemented.
+  std::vector<RtpHeaderExtensionParameters> header_extensions;
+
+  std::vector<RtpEncodingParameters> encodings;
+
+  // TODO(deadbeef): Not implemented.
+  DegradationPreference degradation_preference =
+      DegradationPreference::BALANCED;
+
   bool operator==(const RtpParameters& o) const {
-    return encodings == o.encodings && codecs == o.codecs;
+    return mid == o.mid && codecs == o.codecs &&
+           header_extensions == o.header_extensions &&
+           encodings == o.encodings &&
+           degradation_preference == o.degradation_preference;
   }
   bool operator!=(const RtpParameters& o) const { return !(*this == o); }
 };