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/*
* Copyright (c) 2011 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.
*/
// 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.
// A spec-compliant way to achieve this is to use RIDs and Simulcast attribute
// instead of the ssrc-group. In this method, the StreamParam object will
// have multiple RidDescriptions, each corresponding to a simulcast layer
// and the media section will have a simulcast attribute that indicates
// that these layers are for the same source. This also removes the extra
// lines for redundancy streams, as the same RIDs appear in the redundancy
// packets.
// Note: in the spec compliant simulcast scenario, some of the RIDs might be
// alternatives for one another (such as different encodings for same data).
// In the context of the StreamParams class, the notion of alternatives does
// not exist and all the RIDs will describe different layers of the same source.
// When the StreamParams class is used to configure the media engine, simulcast
// considerations will be used to remove the alternative layers outside of this
// class.
// As an example, let the simulcast layers have RID 10, 20, 30.
// StreamParams would contain rid = { 10, 20, 30 }.
// MediaSection would contain SimulcastDescription specifying these rids.
// a=simulcast:send 10;20;30 (or a=simulcast:send 10,20;30 or similar).
#ifndef MEDIA_BASE_STREAM_PARAMS_H_
#define MEDIA_BASE_STREAM_PARAMS_H_
#include <stddef.h>
#include <cstdint>
#include <string>
#include <vector>
#include "absl/algorithm/container.h"
#include "media/base/rid_description.h"
#include "rtc_base/unique_id_generator.h"
namespace cricket {
extern const char kFecSsrcGroupSemantics[];
extern const char kFecFrSsrcGroupSemantics[];
extern const char kFidSsrcGroupSemantics[];
extern const char kSimSsrcGroupSemantics[];
struct SsrcGroup {
SsrcGroup(const std::string& usage, const std::vector<uint32_t>& ssrcs);
SsrcGroup(const SsrcGroup&);
SsrcGroup(SsrcGroup&&);
~SsrcGroup();
SsrcGroup& operator=(const SsrcGroup&);
SsrcGroup& operator=(SsrcGroup&&);
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_t> ssrcs; // SSRCs of this type.
};
// StreamParams is used to represent a sender/track in a SessionDescription.
// In Plan B, this means that multiple StreamParams can exist within one
// MediaContentDescription, while in UnifiedPlan this means that there is one
// StreamParams per MediaContentDescription.
struct StreamParams {
StreamParams();
StreamParams(const StreamParams&);
StreamParams(StreamParams&&);
~StreamParams();
StreamParams& operator=(const StreamParams&);
StreamParams& operator=(StreamParams&&);
static StreamParams CreateLegacy(uint32_t ssrc) {
StreamParams stream;
stream.ssrcs.push_back(ssrc);
return stream;
}
bool operator==(const StreamParams& other) const;
bool operator!=(const StreamParams& other) const { return !(*this == other); }
uint32_t first_ssrc() const {
if (ssrcs.empty()) {
return 0;
}
return ssrcs[0];
}
bool has_ssrcs() const { return !ssrcs.empty(); }
bool has_ssrc(uint32_t ssrc) const {
return absl::c_linear_search(ssrcs, ssrc);
}
void add_ssrc(uint32_t 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 (const SsrcGroup& ssrc_group : ssrc_groups) {
if (ssrc_group.has_semantics(semantics)) {
return &ssrc_group;
}
}
return NULL;
}
// Convenience function to add an FID ssrc for a primary_ssrc
// that's already been added.
bool AddFidSsrc(uint32_t primary_ssrc, uint32_t 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.
bool GetFidSsrc(uint32_t primary_ssrc, uint32_t* fid_ssrc) const {
return GetSecondarySsrc(kFidSsrcGroupSemantics, primary_ssrc, fid_ssrc);
}
// Convenience function to add an FEC-FR ssrc for a primary_ssrc
// that's already been added.
bool AddFecFrSsrc(uint32_t primary_ssrc, uint32_t fecfr_ssrc) {
return AddSecondarySsrc(kFecFrSsrcGroupSemantics, primary_ssrc, fecfr_ssrc);
}
// Convenience function to lookup the FEC-FR ssrc for a primary_ssrc.
// Returns false if primary_ssrc not found or FEC-FR not defined for it.
bool GetFecFrSsrc(uint32_t primary_ssrc, uint32_t* fecfr_ssrc) const {
return GetSecondarySsrc(kFecFrSsrcGroupSemantics, primary_ssrc, fecfr_ssrc);
}
// Convenience function to populate the StreamParams with the requested number
// of SSRCs along with accompanying FID and FEC-FR ssrcs if requested.
// SSRCs are generated using the given generator.
void GenerateSsrcs(int num_layers,
bool generate_fid,
bool generate_fec_fr,
rtc::UniqueRandomIdGenerator* ssrc_generator);
// Convenience to get all the SIM SSRCs if there are SIM ssrcs, or
// the first SSRC otherwise.
void GetPrimarySsrcs(std::vector<uint32_t>* ssrcs) const;
// Convenience to get all the secondary SSRCs for the given primary ssrcs
// of a particular semantic.
// If a given primary SSRC does not have a secondary SSRC, the list of
// secondary SSRCS will be smaller than the list of primary SSRCs.
void GetSecondarySsrcs(const std::string& semantic,
const std::vector<uint32_t>& primary_ssrcs,
std::vector<uint32_t>* fid_ssrcs) const;
// Convenience to get all the FID SSRCs for the given primary ssrcs.
// If a given primary SSRC does not have a FID SSRC, the list of FID
// SSRCS will be smaller than the list of primary SSRCs.
void GetFidSsrcs(const std::vector<uint32_t>& primary_ssrcs,
std::vector<uint32_t>* fid_ssrcs) const;
// Stream ids serialized to SDP.
std::vector<std::string> stream_ids() const;
void set_stream_ids(const std::vector<std::string>& stream_ids);
// Returns the first stream id or "" if none exist. This method exists only
// as temporary backwards compatibility with the old sync_label.
std::string first_stream_id() const;
std::string ToString() const;
// A unique identifier of the StreamParams object. When the SDP is created,
// this comes from the track ID of the sender that the StreamParams object
// is associated with.
std::string id;
// There may be no SSRCs stored in unsignaled case when stream_ids are
// signaled with a=msid lines.
std::vector<uint32_t> ssrcs; // All SSRCs for this source
std::vector<SsrcGroup> ssrc_groups; // e.g. FID, FEC, SIM
std::string cname; // RTCP CNAME
// RID functionality according to
// Each layer can be represented by a RID identifier and can also have
// restrictions (such as max-width, max-height, etc.)
// If the track has multiple layers (ex. Simulcast), each layer will be
// represented by a RID.
bool has_rids() const { return !rids_.empty(); }
const std::vector<RidDescription>& rids() const { return rids_; }
void set_rids(const std::vector<RidDescription>& rids) { rids_ = rids; }
private:
bool AddSecondarySsrc(const std::string& semantics,
uint32_t primary_ssrc,
uint32_t secondary_ssrc);
bool GetSecondarySsrc(const std::string& semantics,
uint32_t primary_ssrc,
uint32_t* secondary_ssrc) const;
// The stream IDs of the sender that the StreamParams object is associated
// with. In Plan B this should always be size of 1, while in Unified Plan this
// could be none or multiple stream IDs.
std::vector<std::string> stream_ids_;
std::vector<RidDescription> rids_;
};
// A Stream can be selected by either id or ssrc.
struct StreamSelector {
explicit StreamSelector(uint32_t ssrc) : ssrc(ssrc) {}
explicit StreamSelector(const std::string& streamid)
: ssrc(0), streamid(streamid) {}
bool Matches(const StreamParams& stream) const {
if (ssrc == 0) {
return stream.id == streamid;
} else {
return stream.has_ssrc(ssrc);
}
}
uint32_t ssrc;
std::string streamid;
};
typedef std::vector<StreamParams> StreamParamsVec;
template <class Condition>
const StreamParams* GetStream(const StreamParamsVec& streams,
Condition condition) {
auto found = absl::c_find_if(streams, condition);
return found == streams.end() ? nullptr : &(*found);
}
template <class Condition>
StreamParams* GetStream(StreamParamsVec& streams, Condition condition) {
auto found = absl::c_find_if(streams, condition);
return found == streams.end() ? nullptr : &(*found);
}
inline bool HasStreamWithNoSsrcs(const StreamParamsVec& streams) {
return GetStream(streams,
[](const StreamParams& sp) { return !sp.has_ssrcs(); });
}
inline const StreamParams* GetStreamBySsrc(const StreamParamsVec& streams,
uint32_t ssrc) {
return GetStream(
streams, [&ssrc](const StreamParams& sp) { return sp.has_ssrc(ssrc); });
}
inline const StreamParams* GetStreamByIds(const StreamParamsVec& streams,
const std::string& id) {
return GetStream(streams,
[&id](const StreamParams& sp) { return sp.id == id; });
}
inline StreamParams* GetStreamByIds(StreamParamsVec& streams,
const std::string& id) {
return GetStream(streams,
[&id](const StreamParams& sp) { return sp.id == id; });
}
inline const StreamParams* GetStream(const StreamParamsVec& streams,
const StreamSelector& selector) {
return GetStream(streams, [&selector](const StreamParams& sp) {
return selector.Matches(sp);
});
}
template <class Condition>
bool RemoveStream(StreamParamsVec* streams, Condition condition) {
auto iter(std::remove_if(streams->begin(), streams->end(), condition));
if (iter == streams->end())
return false;
streams->erase(iter, streams->end());
return true;
}
// Removes the stream from streams. Returns true if a stream is
// found and removed.
inline bool RemoveStream(StreamParamsVec* streams,
const StreamSelector& selector) {
return RemoveStream(streams, [&selector](const StreamParams& sp) {
return selector.Matches(sp);
});
}
inline bool RemoveStreamBySsrc(StreamParamsVec* streams, uint32_t ssrc) {
return RemoveStream(
streams, [&ssrc](const StreamParams& sp) { return sp.has_ssrc(ssrc); });
}
inline bool RemoveStreamByIds(StreamParamsVec* streams, const std::string& id) {
return RemoveStream(streams,
[&id](const StreamParams& sp) { return sp.id == id; });
}
} // namespace cricket
#endif // MEDIA_BASE_STREAM_PARAMS_H_