webrtc_m130/media/base/codec.h

/*
 *  Copyright (c) 2004 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 MEDIA_BASE_CODEC_H_
#define MEDIA_BASE_CODEC_H_

#include <map>
#include <set>
#include <string>
#include <vector>

#include "absl/container/inlined_vector.h"
#include "absl/strings/string_view.h"
#include "absl/types/optional.h"
#include "api/field_trials_view.h"
#include "api/rtp_parameters.h"
#include "api/video_codecs/sdp_video_format.h"
#include "media/base/media_constants.h"
#include "rtc_base/system/rtc_export.h"

namespace cricket {

typedef std::map<std::string, std::string> CodecParameterMap;

class FeedbackParam {
 public:
  FeedbackParam() = default;
  FeedbackParam(absl::string_view id, const std::string& param)
      : id_(id), param_(param) {}
  explicit FeedbackParam(absl::string_view id)
      : id_(id), param_(kParamValueEmpty) {}

  bool operator==(const FeedbackParam& other) const;

  const std::string& id() const { return id_; }
  const std::string& param() const { return param_; }

 private:
  std::string id_;     // e.g. "nack", "ccm"
  std::string param_;  // e.g. "", "rpsi", "fir"
};

class FeedbackParams {
 public:
  FeedbackParams();
  ~FeedbackParams();
  bool operator==(const FeedbackParams& other) const;

  bool Has(const FeedbackParam& param) const;
  void Add(const FeedbackParam& param);

  void Intersect(const FeedbackParams& from);

  const std::vector<FeedbackParam>& params() const { return params_; }

 private:
  bool HasDuplicateEntries() const;

  std::vector<FeedbackParam> params_;
};

struct RTC_EXPORT Codec {
  enum class Type {
    kAudio,
    kVideo,
  };

  enum class ResiliencyType {
    kNone,
    kRed,
    kUlpfec,
    kFlexfec,
    kRtx,
  };

  Type type;
  int id;
  std::string name;
  int clockrate;

  // Audio only
  // Can be used to override the target bitrate in the encoder.
  // TODO(orphis): Remove in favor of alternative APIs
  int bitrate;
  size_t channels;

  // Video only
  absl::optional<std::string> packetization;
  absl::InlinedVector<webrtc::ScalabilityMode, webrtc::kScalabilityModeCount>
      scalability_modes;

  // Non key-value parameters such as the telephone-event "0‐15" are
  // represented using an empty string as key, i.e. {"": "0-15"}.
  CodecParameterMap params;
  FeedbackParams feedback_params;

  Codec(const Codec& c);
  Codec(Codec&& c);

  virtual ~Codec();

  // Indicates if this codec is compatible with the specified codec by
  // checking the assigned id and profile values for the relevant video codecs.
  // H264 levels are not compared.
  bool Matches(const Codec& codec,
               const webrtc::FieldTrialsView* field_trials = nullptr) const;
  bool MatchesCapability(const webrtc::RtpCodecCapability& capability) const;

  // Find the parameter for `name` and write the value to `out`.
  bool GetParam(const std::string& name, std::string* out) const;
  bool GetParam(const std::string& name, int* out) const;

  void SetParam(const std::string& name, const std::string& value);
  void SetParam(const std::string& name, int value);

  // It is safe to input a non-existent parameter.
  // Returns true if the parameter existed, false if it did not exist.
  bool RemoveParam(const std::string& name);

  bool HasFeedbackParam(const FeedbackParam& param) const;
  void AddFeedbackParam(const FeedbackParam& param);

  // Filter `this` feedbacks params such that only those shared by both `this`
  // and `other` are kept.
  void IntersectFeedbackParams(const Codec& other);

  virtual webrtc::RtpCodecParameters ToCodecParameters() const;

  // The codec represent an actual media codec, and not a resiliency codec.
  bool IsMediaCodec() const;
  // The codec represent a resiliency codec such as RED, RTX or FEC variants.
  bool IsResiliencyCodec() const;
  ResiliencyType GetResiliencyType() const;

  // Validates a VideoCodec's payload type, dimensions and bitrates etc. If they
  // don't make sense (such as max < min bitrate), and error is logged and
  // ValidateCodecFormat returns false.
  bool ValidateCodecFormat() const;

  std::string ToString() const;

  Codec& operator=(const Codec& c);
  Codec& operator=(Codec&& c);

  bool operator==(const Codec& c) const;

  bool operator!=(const Codec& c) const { return !(*this == c); }

 protected:
  // Creates an empty codec.
  explicit Codec(Type type);
  // Creates a codec with the given parameters.
  Codec(Type type, int id, const std::string& name, int clockrate);
  Codec(Type type,
        int id,
        const std::string& name,
        int clockrate,
        size_t channels);
  explicit Codec(const webrtc::SdpVideoFormat& c);
};

struct AudioCodec : public Codec {
  // Creates a codec with the given parameters.
  AudioCodec(int id,
             const std::string& name,
             int clockrate,
             int unused_bitrate,
             size_t channels);
  // Creates an empty codec.
  AudioCodec();
  AudioCodec(const AudioCodec& c);
  AudioCodec(AudioCodec&& c);
  ~AudioCodec() override = default;

  AudioCodec& operator=(const AudioCodec& c);
  AudioCodec& operator=(AudioCodec&& c);
};

struct RTC_EXPORT VideoCodec : public Codec {
  // Creates a codec with the given parameters.
  VideoCodec(int id, const std::string& name);
  // Creates a codec with the given name and empty id.
  explicit VideoCodec(const std::string& name);
  // Creates an empty codec.
  VideoCodec();
  VideoCodec(const VideoCodec& c);
  explicit VideoCodec(const webrtc::SdpVideoFormat& c);
  VideoCodec(VideoCodec&& c);
  ~VideoCodec() override = default;

  VideoCodec& operator=(const VideoCodec& c);
  VideoCodec& operator=(VideoCodec&& c);

  [[deprecated]] static VideoCodec CreateRtxCodec(int rtx_payload_type,
                                                  int associated_payload_type);

  enum [[deprecated]] CodecType {
    CODEC_VIDEO,
    CODEC_RED,
    CODEC_ULPFEC,
    CODEC_FLEXFEC,
    CODEC_RTX,
  };

  [[deprecated]] CodecType GetCodecType() const;

 private:
  void SetDefaultParameters();
};

AudioCodec CreateAudioCodec(int id,
                            const std::string& name,
                            int clockrate,
                            size_t channels);
VideoCodec CreateVideoCodec(const std::string& name);
VideoCodec CreateVideoCodec(int id, const std::string& name);
VideoCodec CreateVideoRtxCodec(int rtx_payload_type,
                               int associated_payload_type);

// Get the codec setting associated with `payload_type`. If there
// is no codec associated with that payload type it returns nullptr.
template <class Codec>
const Codec* FindCodecById(const std::vector<Codec>& codecs, int payload_type) {
  for (const auto& codec : codecs) {
    if (codec.id == payload_type)
      return &codec;
  }
  return nullptr;
}

bool HasLntf(const Codec& codec);
bool HasNack(const Codec& codec);
bool HasRemb(const Codec& codec);
bool HasRrtr(const Codec& codec);
bool HasTransportCc(const Codec& codec);
// Returns the first codec in `supported_codecs` that matches `codec`, or
// nullptr if no codec matches.
const VideoCodec* FindMatchingCodec(
    const std::vector<VideoCodec>& supported_codecs,
    const VideoCodec& codec);

RTC_EXPORT void AddH264ConstrainedBaselineProfileToSupportedFormats(
    std::vector<webrtc::SdpVideoFormat>* supported_formats);

}  // namespace cricket

#endif  // MEDIA_BASE_CODEC_H_