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* Copyright 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.
// Types and classes used in media session descriptions.
#include <algorithm>
#include <map>
#include <string>
#include <vector>
#include "webrtc/media/base/codec.h"
#include "webrtc/media/base/cryptoparams.h"
#include "webrtc/media/base/mediachannel.h"
#include "webrtc/media/base/mediaconstants.h"
#include "webrtc/media/base/mediaengine.h" // For DataChannelType
#include "webrtc/media/base/streamparams.h"
#include "webrtc/p2p/base/sessiondescription.h"
#include "webrtc/p2p/base/transport.h"
#include "webrtc/p2p/base/transportdescriptionfactory.h"
namespace cricket {
class ChannelManager;
typedef std::vector<AudioCodec> AudioCodecs;
typedef std::vector<VideoCodec> VideoCodecs;
typedef std::vector<DataCodec> DataCodecs;
typedef std::vector<CryptoParams> CryptoParamsVec;
typedef std::vector<webrtc::RtpExtension> RtpHeaderExtensions;
enum MediaType {
std::string MediaTypeToString(MediaType type);
enum MediaContentDirection {
std::string MediaContentDirectionToString(MediaContentDirection direction);
enum CryptoType {
extern const char kMediaProtocolAvpf[];
extern const char kMediaProtocolSavpf[];
extern const char kMediaProtocolDtlsSavpf[];
extern const char kMediaProtocolRtpPrefix[];
extern const char kMediaProtocolSctp[];
extern const char kMediaProtocolDtlsSctp[];
extern const char kMediaProtocolUdpDtlsSctp[];
extern const char kMediaProtocolTcpDtlsSctp[];
// Options to control how session descriptions are generated.
const int kAutoBandwidth = -1;
const int kBufferedModeDisabled = 0;
// Default RTCP CNAME for unit tests.
const char kDefaultRtcpCname[] = "DefaultRtcpCname";
struct RtpTransceiverDirection {
bool send;
bool recv;
RtpTransceiverDirection(bool send, bool recv) : send(send), recv(recv) {}
bool operator==(const RtpTransceiverDirection& o) const {
return send == o.send && recv == o.recv;
bool operator!=(const RtpTransceiverDirection& o) const {
return !(*this == o);
static RtpTransceiverDirection FromMediaContentDirection(
MediaContentDirection md);
MediaContentDirection ToMediaContentDirection() const;
NegotiateRtpTransceiverDirection(RtpTransceiverDirection offer,
RtpTransceiverDirection wants);
struct MediaSessionOptions {
: recv_audio(true),
vad_enabled(true), // When disabled, removes all CN codecs from SDP.
rtcp_cname(kDefaultRtcpCname) {}
bool has_audio() const {
return recv_audio || HasSendMediaStream(MEDIA_TYPE_AUDIO);
bool has_video() const {
return recv_video || HasSendMediaStream(MEDIA_TYPE_VIDEO);
bool has_data() const { return data_channel_type != DCT_NONE; }
// Add a stream with MediaType type and id.
// All streams with the same sync_label will get the same CNAME.
// All ids must be unique.
void AddSendStream(MediaType type,
const std::string& id,
const std::string& sync_label);
void AddSendVideoStream(const std::string& id,
const std::string& sync_label,
int num_sim_layers);
void RemoveSendStream(MediaType type, const std::string& id);
// Helper function.
void AddSendStreamInternal(MediaType type,
const std::string& id,
const std::string& sync_label,
int num_sim_layers);
bool HasSendMediaStream(MediaType type) const;
// TODO(deadbeef): Put all the audio/video/data-specific options into a map
// structure (content name -> options).
// MediaSessionDescriptionFactory assumes there will never be more than one
// audio/video/data content, but this will change with unified plan.
bool recv_audio;
bool recv_video;
DataChannelType data_channel_type;
bool is_muc;
bool vad_enabled;
bool rtcp_mux_enabled;
bool bundle_enabled;
// bps. -1 == auto.
int video_bandwidth;
int data_bandwidth;
// content name ("mid") => options.
std::map<std::string, TransportOptions> transport_options;
std::string rtcp_cname;
struct Stream {
Stream(MediaType type,
const std::string& id,
const std::string& sync_label,
int num_sim_layers)
: type(type), id(id), sync_label(sync_label),
num_sim_layers(num_sim_layers) {
MediaType type;
std::string id;
std::string sync_label;
int num_sim_layers;
typedef std::vector<Stream> Streams;
Streams streams;
// "content" (as used in XEP-0166) descriptions for voice and video.
class MediaContentDescription : public ContentDescription {
MediaContentDescription() {}
virtual MediaType type() const = 0;
virtual bool has_codecs() const = 0;
// |protocol| is the expected media transport protocol, such as RTP/AVPF,
std::string protocol() const { return protocol_; }
void set_protocol(const std::string& protocol) { protocol_ = protocol; }
MediaContentDirection direction() const { return direction_; }
void set_direction(MediaContentDirection direction) {
direction_ = direction;
bool rtcp_mux() const { return rtcp_mux_; }
void set_rtcp_mux(bool mux) { rtcp_mux_ = mux; }
bool rtcp_reduced_size() const { return rtcp_reduced_size_; }
void set_rtcp_reduced_size(bool reduced_size) {
rtcp_reduced_size_ = reduced_size;
int bandwidth() const { return bandwidth_; }
void set_bandwidth(int bandwidth) { bandwidth_ = bandwidth; }
const std::vector<CryptoParams>& cryptos() const { return cryptos_; }
void AddCrypto(const CryptoParams& params) {
void set_cryptos(const std::vector<CryptoParams>& cryptos) {
cryptos_ = cryptos;
CryptoType crypto_required() const { return crypto_required_; }
void set_crypto_required(CryptoType type) {
crypto_required_ = type;
const RtpHeaderExtensions& rtp_header_extensions() const {
return rtp_header_extensions_;
void set_rtp_header_extensions(const RtpHeaderExtensions& extensions) {
rtp_header_extensions_ = extensions;
rtp_header_extensions_set_ = true;
void AddRtpHeaderExtension(const webrtc::RtpExtension& ext) {
rtp_header_extensions_set_ = true;
void AddRtpHeaderExtension(const cricket::RtpHeaderExtension& ext) {
webrtc::RtpExtension webrtc_extension;
webrtc_extension.uri = ext.uri; =;
rtp_header_extensions_set_ = true;
void ClearRtpHeaderExtensions() {
rtp_header_extensions_set_ = true;
// We can't always tell if an empty list of header extensions is
// because the other side doesn't support them, or just isn't hooked up to
// signal them. For now we assume an empty list means no signaling, but
// provide the ClearRtpHeaderExtensions method to allow "no support" to be
// clearly indicated (i.e. when derived from other information).
bool rtp_header_extensions_set() const {
return rtp_header_extensions_set_;
// True iff the client supports multiple streams.
void set_multistream(bool multistream) { multistream_ = multistream; }
bool multistream() const { return multistream_; }
const StreamParamsVec& streams() const {
return streams_;
// TODO(pthatcher): Remove this by giving access
// to MediaContentDescription
StreamParamsVec& mutable_streams() {
return streams_;
void AddStream(const StreamParams& stream) {
// Legacy streams have an ssrc, but nothing else.
void AddLegacyStream(uint32_t ssrc) {
void AddLegacyStream(uint32_t ssrc, uint32_t fid_ssrc) {
StreamParams sp = StreamParams::CreateLegacy(ssrc);
sp.AddFidSsrc(ssrc, fid_ssrc);
// Sets the CNAME of all StreamParams if it have not been set.
// This can be used to set the CNAME of legacy streams.
void SetCnameIfEmpty(const std::string& cname) {
for (cricket::StreamParamsVec::iterator it = streams_.begin();
it != streams_.end(); ++it) {
if (it->cname.empty())
it->cname = cname;
uint32_t first_ssrc() const {
if (streams_.empty()) {
return 0;
return streams_[0].first_ssrc();
bool has_ssrcs() const {
if (streams_.empty()) {
return false;
return streams_[0].has_ssrcs();
void set_conference_mode(bool enable) { conference_mode_ = enable; }
bool conference_mode() const { return conference_mode_; }
void set_partial(bool partial) { partial_ = partial; }
bool partial() const { return partial_; }
void set_buffered_mode_latency(int latency) {
buffered_mode_latency_ = latency;
int buffered_mode_latency() const { return buffered_mode_latency_; }
bool rtcp_mux_ = false;
bool rtcp_reduced_size_ = false;
int bandwidth_ = kAutoBandwidth;
std::string protocol_;
std::vector<CryptoParams> cryptos_;
CryptoType crypto_required_ = CT_NONE;
std::vector<webrtc::RtpExtension> rtp_header_extensions_;
bool rtp_header_extensions_set_ = false;
bool multistream_ = false;
StreamParamsVec streams_;
bool conference_mode_ = false;
bool partial_ = false;
int buffered_mode_latency_ = kBufferedModeDisabled;
MediaContentDirection direction_ = MD_SENDRECV;
template <class C>
class MediaContentDescriptionImpl : public MediaContentDescription {
typedef C CodecType;
// Codecs should be in preference order (most preferred codec first).
const std::vector<C>& codecs() const { return codecs_; }
void set_codecs(const std::vector<C>& codecs) { codecs_ = codecs; }
virtual bool has_codecs() const { return !codecs_.empty(); }
bool HasCodec(int id) {
bool found = false;
for (typename std::vector<C>::iterator iter = codecs_.begin();
iter != codecs_.end(); ++iter) {
if (iter->id == id) {
found = true;
return found;
void AddCodec(const C& codec) {
void AddOrReplaceCodec(const C& codec) {
for (typename std::vector<C>::iterator iter = codecs_.begin();
iter != codecs_.end(); ++iter) {
if (iter->id == {
*iter = codec;
void AddCodecs(const std::vector<C>& codecs) {
typename std::vector<C>::const_iterator codec;
for (codec = codecs.begin(); codec != codecs.end(); ++codec) {
std::vector<C> codecs_;
class AudioContentDescription : public MediaContentDescriptionImpl<AudioCodec> {
AudioContentDescription() :
agc_minus_10db_(false) {}
virtual ContentDescription* Copy() const {
return new AudioContentDescription(*this);
virtual MediaType type() const { return MEDIA_TYPE_AUDIO; }
const std::string &lang() const { return lang_; }
void set_lang(const std::string &lang) { lang_ = lang; }
bool agc_minus_10db() const { return agc_minus_10db_; }
void set_agc_minus_10db(bool enable) {
agc_minus_10db_ = enable;
bool agc_minus_10db_;
std::string lang_;
class VideoContentDescription : public MediaContentDescriptionImpl<VideoCodec> {
virtual ContentDescription* Copy() const {
return new VideoContentDescription(*this);
virtual MediaType type() const { return MEDIA_TYPE_VIDEO; }
class DataContentDescription : public MediaContentDescriptionImpl<DataCodec> {
virtual ContentDescription* Copy() const {
return new DataContentDescription(*this);
virtual MediaType type() const { return MEDIA_TYPE_DATA; }
// Creates media session descriptions according to the supplied codecs and
// other fields, as well as the supplied per-call options.
// When creating answers, performs the appropriate negotiation
// of the various fields to determine the proper result.
class MediaSessionDescriptionFactory {
// Default ctor; use methods below to set configuration.
// The TransportDescriptionFactory is not owned by MediaSessionDescFactory,
// so it must be kept alive by the user of this class.
explicit MediaSessionDescriptionFactory(
const TransportDescriptionFactory* factory);
// This helper automatically sets up the factory to get its configuration
// from the specified ChannelManager.
MediaSessionDescriptionFactory(ChannelManager* cmanager,
const TransportDescriptionFactory* factory);
const AudioCodecs& audio_sendrecv_codecs() const;
const AudioCodecs& audio_send_codecs() const;
const AudioCodecs& audio_recv_codecs() const;
void set_audio_codecs(const AudioCodecs& send_codecs,
const AudioCodecs& recv_codecs);
void set_audio_rtp_header_extensions(const RtpHeaderExtensions& extensions) {
audio_rtp_extensions_ = extensions;
const RtpHeaderExtensions& audio_rtp_header_extensions() const {
return audio_rtp_extensions_;
const VideoCodecs& video_codecs() const { return video_codecs_; }
void set_video_codecs(const VideoCodecs& codecs) { video_codecs_ = codecs; }
void set_video_rtp_header_extensions(const RtpHeaderExtensions& extensions) {
video_rtp_extensions_ = extensions;
const RtpHeaderExtensions& video_rtp_header_extensions() const {
return video_rtp_extensions_;
const DataCodecs& data_codecs() const { return data_codecs_; }
void set_data_codecs(const DataCodecs& codecs) { data_codecs_ = codecs; }
SecurePolicy secure() const { return secure_; }
void set_secure(SecurePolicy s) { secure_ = s; }
// Decides if a StreamParams shall be added to the audio and video media
// content in SessionDescription when CreateOffer and CreateAnswer is called
// even if |options| don't include a Stream. This is needed to support legacy
// applications. |add_legacy_| is true per default.
void set_add_legacy_streams(bool add_legacy) { add_legacy_ = add_legacy; }
SessionDescription* CreateOffer(
const MediaSessionOptions& options,
const SessionDescription* current_description) const;
SessionDescription* CreateAnswer(
const SessionDescription* offer,
const MediaSessionOptions& options,
const SessionDescription* current_description) const;
const AudioCodecs& GetAudioCodecsForOffer(
const RtpTransceiverDirection& direction) const;
const AudioCodecs& GetAudioCodecsForAnswer(
const RtpTransceiverDirection& offer,
const RtpTransceiverDirection& answer) const;
void GetCodecsToOffer(const SessionDescription* current_description,
const AudioCodecs& supported_audio_codecs,
const VideoCodecs& supported_video_codecs,
const DataCodecs& supported_data_codecs,
AudioCodecs* audio_codecs,
VideoCodecs* video_codecs,
DataCodecs* data_codecs) const;
void GetRtpHdrExtsToOffer(const SessionDescription* current_description,
RtpHeaderExtensions* audio_extensions,
RtpHeaderExtensions* video_extensions) const;
bool AddTransportOffer(
const std::string& content_name,
const TransportOptions& transport_options,
const SessionDescription* current_desc,
SessionDescription* offer) const;
TransportDescription* CreateTransportAnswer(
const std::string& content_name,
const SessionDescription* offer_desc,
const TransportOptions& transport_options,
const SessionDescription* current_desc) const;
bool AddTransportAnswer(
const std::string& content_name,
const TransportDescription& transport_desc,
SessionDescription* answer_desc) const;
// Helpers for adding media contents to the SessionDescription. Returns true
// it succeeds or the media content is not needed, or false if there is any
// error.
bool AddAudioContentForOffer(
const MediaSessionOptions& options,
const SessionDescription* current_description,
const RtpHeaderExtensions& audio_rtp_extensions,
const AudioCodecs& audio_codecs,
StreamParamsVec* current_streams,
SessionDescription* desc) const;
bool AddVideoContentForOffer(
const MediaSessionOptions& options,
const SessionDescription* current_description,
const RtpHeaderExtensions& video_rtp_extensions,
const VideoCodecs& video_codecs,
StreamParamsVec* current_streams,
SessionDescription* desc) const;
bool AddDataContentForOffer(
const MediaSessionOptions& options,
const SessionDescription* current_description,
DataCodecs* data_codecs,
StreamParamsVec* current_streams,
SessionDescription* desc) const;
bool AddAudioContentForAnswer(
const SessionDescription* offer,
const MediaSessionOptions& options,
const SessionDescription* current_description,
StreamParamsVec* current_streams,
SessionDescription* answer) const;
bool AddVideoContentForAnswer(
const SessionDescription* offer,
const MediaSessionOptions& options,
const SessionDescription* current_description,
StreamParamsVec* current_streams,
SessionDescription* answer) const;
bool AddDataContentForAnswer(
const SessionDescription* offer,
const MediaSessionOptions& options,
const SessionDescription* current_description,
StreamParamsVec* current_streams,
SessionDescription* answer) const;
AudioCodecs audio_send_codecs_;
AudioCodecs audio_recv_codecs_;
AudioCodecs audio_sendrecv_codecs_;
RtpHeaderExtensions audio_rtp_extensions_;
VideoCodecs video_codecs_;
RtpHeaderExtensions video_rtp_extensions_;
DataCodecs data_codecs_;
SecurePolicy secure_;
bool add_legacy_;
std::string lang_;
const TransportDescriptionFactory* transport_desc_factory_;
// Convenience functions.
bool IsMediaContent(const ContentInfo* content);
bool IsAudioContent(const ContentInfo* content);
bool IsVideoContent(const ContentInfo* content);
bool IsDataContent(const ContentInfo* content);
const ContentInfo* GetFirstMediaContent(const ContentInfos& contents,
MediaType media_type);
const ContentInfo* GetFirstAudioContent(const ContentInfos& contents);
const ContentInfo* GetFirstVideoContent(const ContentInfos& contents);
const ContentInfo* GetFirstDataContent(const ContentInfos& contents);
const ContentInfo* GetFirstAudioContent(const SessionDescription* sdesc);
const ContentInfo* GetFirstVideoContent(const SessionDescription* sdesc);
const ContentInfo* GetFirstDataContent(const SessionDescription* sdesc);
const AudioContentDescription* GetFirstAudioContentDescription(
const SessionDescription* sdesc);
const VideoContentDescription* GetFirstVideoContentDescription(
const SessionDescription* sdesc);
const DataContentDescription* GetFirstDataContentDescription(
const SessionDescription* sdesc);
// Non-const versions of the above functions.
// Useful when modifying an existing description.
ContentInfo* GetFirstMediaContent(ContentInfos& contents, MediaType media_type);
ContentInfo* GetFirstAudioContent(ContentInfos& contents);
ContentInfo* GetFirstVideoContent(ContentInfos& contents);
ContentInfo* GetFirstDataContent(ContentInfos& contents);
ContentInfo* GetFirstAudioContent(SessionDescription* sdesc);
ContentInfo* GetFirstVideoContent(SessionDescription* sdesc);
ContentInfo* GetFirstDataContent(SessionDescription* sdesc);
AudioContentDescription* GetFirstAudioContentDescription(
SessionDescription* sdesc);
VideoContentDescription* GetFirstVideoContentDescription(
SessionDescription* sdesc);
DataContentDescription* GetFirstDataContentDescription(
SessionDescription* sdesc);
void GetSupportedAudioCryptoSuites(std::vector<int>* crypto_suites);
void GetSupportedVideoCryptoSuites(std::vector<int>* crypto_suites);
void GetSupportedDataCryptoSuites(std::vector<int>* crypto_suites);
void GetDefaultSrtpCryptoSuites(std::vector<int>* crypto_suites);
void GetSupportedAudioCryptoSuiteNames(
std::vector<std::string>* crypto_suite_names);
void GetSupportedVideoCryptoSuiteNames(
std::vector<std::string>* crypto_suite_names);
void GetSupportedDataCryptoSuiteNames(
std::vector<std::string>* crypto_suite_names);
void GetDefaultSrtpCryptoSuiteNames(
std::vector<std::string>* crypto_suite_names);
} // namespace cricket