webrtc/talk/media/base/streamparams.h

/*
 * libjingle
 * Copyright 2011 Google Inc.
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 *     derived from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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// This file contains structures for describing SSRCs from a media source such
// as a MediaStreamTrack when it is sent across an RTP session. Multiple media
// sources may be sent across the same RTP session, each of them will be
// described by one StreamParams object
// SsrcGroup is used to describe the relationship between the SSRCs that
// are used for this media source.
// E.x: Consider a source that is sent as 3 simulcast streams
// Let the simulcast elements have SSRC 10, 20, 30.
// Let each simulcast element use FEC and let the protection packets have
// SSRC 11,21,31.
// To describe this 4 SsrcGroups are needed,
// StreamParams would then contain ssrc = {10,11,20,21,30,31} and
// ssrc_groups = {{SIM,{10,20,30}, {FEC,{10,11}, {FEC, {20,21}, {FEC {30,31}}}
// Please see RFC 5576.

#ifndef TALK_MEDIA_BASE_STREAMPARAMS_H_
#define TALK_MEDIA_BASE_STREAMPARAMS_H_

#include <algorithm>
#include <string>
#include <set>
#include <vector>

#include "talk/base/basictypes.h"

namespace cricket {

extern const char kFecSsrcGroupSemantics[];
extern const char kFidSsrcGroupSemantics[];
extern const char kSimSsrcGroupSemantics[];

struct SsrcGroup {
  SsrcGroup(const std::string& usage, const std::vector<uint32>& ssrcs)
      : semantics(usage), ssrcs(ssrcs) {
  }

  bool operator==(const SsrcGroup& other) const {
    return (semantics == other.semantics && ssrcs == other.ssrcs);
  }
  bool operator!=(const SsrcGroup &other) const {
    return !(*this == other);
  }

  bool has_semantics(const std::string& semantics) const;

  std::string ToString() const;

  std::string semantics;  // e.g FIX, FEC, SIM.
  std::vector<uint32> ssrcs;  // SSRCs of this type.
};

struct StreamParams {
  static StreamParams CreateLegacy(uint32 ssrc) {
    StreamParams stream;
    stream.ssrcs.push_back(ssrc);
    return stream;
  }

  bool operator==(const StreamParams& other) const {
    return (groupid == other.groupid &&
            id == other.id &&
            ssrcs == other.ssrcs &&
            ssrc_groups == other.ssrc_groups &&
            type == other.type &&
            display == other.display &&
            cname == other.cname &&
            sync_label == other.sync_label);
  }
  bool operator!=(const StreamParams &other) const {
    return !(*this == other);
  }

  uint32 first_ssrc() const {
    if (ssrcs.empty()) {
      return 0;
    }

    return ssrcs[0];
  }
  bool has_ssrcs() const {
    return !ssrcs.empty();
  }
  bool has_ssrc(uint32 ssrc) const {
    return std::find(ssrcs.begin(), ssrcs.end(), ssrc) != ssrcs.end();
  }
  void add_ssrc(uint32 ssrc) {
    ssrcs.push_back(ssrc);
  }
  bool has_ssrc_groups() const {
    return !ssrc_groups.empty();
  }
  bool has_ssrc_group(const std::string& semantics) const {
    return (get_ssrc_group(semantics) != NULL);
  }
  const SsrcGroup* get_ssrc_group(const std::string& semantics) const {
    for (std::vector<SsrcGroup>::const_iterator it = ssrc_groups.begin();
         it != ssrc_groups.end(); ++it) {
      if (it->has_semantics(semantics)) {
        return &(*it);
      }
    }
    return NULL;
  }

  // Convenience function to add an FID ssrc for a primary_ssrc
  // that's already been added.
  inline bool AddFidSsrc(uint32 primary_ssrc, uint32 fid_ssrc) {
    return AddSecondarySsrc(kFidSsrcGroupSemantics, primary_ssrc, fid_ssrc);
  }

  // Convenience function to lookup the FID ssrc for a primary_ssrc.
  // Returns false if primary_ssrc not found or FID not defined for it.
  inline bool GetFidSsrc(uint32 primary_ssrc, uint32* fid_ssrc) const {
    return GetSecondarySsrc(kFidSsrcGroupSemantics, primary_ssrc, fid_ssrc);
  }

  std::string ToString() const;

  // Resource of the MUC jid of the participant of with this stream.
  // For 1:1 calls, should be left empty (which means remote streams
  // and local streams should not be mixed together).
  std::string groupid;
  // Unique per-groupid, not across all groupids
  std::string id;
  std::vector<uint32> ssrcs;  // All SSRCs for this source
  std::vector<SsrcGroup> ssrc_groups;  // e.g. FID, FEC, SIM
  // Examples: "camera", "screencast"
  std::string type;
  // Friendly name describing stream
  std::string display;
  std::string cname;  // RTCP CNAME
  std::string sync_label;  // Friendly name of cname.

 private:
  bool AddSecondarySsrc(const std::string& semantics, uint32 primary_ssrc,
                        uint32 secondary_ssrc);
  bool GetSecondarySsrc(const std::string& semantics, uint32 primary_ssrc,
                        uint32* secondary_ssrc) const;
};

// A Stream can be selected by either groupid+id or ssrc.
struct StreamSelector {
  explicit StreamSelector(uint32 ssrc) :
      ssrc(ssrc) {
  }

  StreamSelector(const std::string& groupid,
                 const std::string& streamid) :
      ssrc(0),
      groupid(groupid),
      streamid(streamid) {
  }

  bool Matches(const StreamParams& stream) const {
    if (ssrc == 0) {
      return stream.groupid == groupid && stream.id == streamid;
    } else {
      return stream.has_ssrc(ssrc);
    }
  }

  uint32 ssrc;
  std::string groupid;
  std::string streamid;
};

typedef std::vector<StreamParams> StreamParamsVec;

// Finds the stream in streams.  Returns true if found.
bool GetStream(const StreamParamsVec& streams,
               const StreamSelector& selector,
               StreamParams* stream_out);
bool GetStreamBySsrc(const StreamParamsVec& streams, uint32 ssrc,
                     StreamParams* stream_out);
bool GetStreamByIds(const StreamParamsVec& streams,
                    const std::string& groupid,
                    const std::string& id,
                    StreamParams* stream_out);

// Removes the stream from streams. Returns true if a stream is
// found and removed.
bool RemoveStream(StreamParamsVec* streams,
                  const StreamSelector& selector);
bool RemoveStreamBySsrc(StreamParamsVec* streams, uint32 ssrc);
bool RemoveStreamByIds(StreamParamsVec* streams,
                       const std::string& groupid,
                       const std::string& id);

// Checks if |sp| defines parameters for a single primary stream. There may
// be an RTX stream associated with the primary stream. Leaving as non-static so
// we can test this function.
bool IsOneSsrcStream(const StreamParams& sp);

// Checks if |sp| defines parameters for one Simulcast stream. There may be RTX
// streams associated with the simulcast streams. Leaving as non-static so we
// can test this function.
bool IsSimulcastStream(const StreamParams& sp);

}  // namespace cricket

#endif  // TALK_MEDIA_BASE_STREAMPARAMS_H_