1 /*
2  *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 #ifndef MEDIA_BASE_RID_DESCRIPTION_H_
12 #define MEDIA_BASE_RID_DESCRIPTION_H_
13 
14 #include <map>
15 #include <string>
16 #include <vector>
17 
18 namespace cricket {
19 
20 enum class RidDirection { kSend, kReceive };
21 
22 // Description of a Restriction Id (RID) according to:
23 // https://tools.ietf.org/html/draft-ietf-mmusic-rid-15
24 // A Restriction Identifier serves two purposes:
25 //   1. Uniquely identifies an RTP stream inside an RTP session.
26 //      When combined with MIDs (https://tools.ietf.org/html/rfc5888),
27 //      RIDs uniquely identify an RTP stream within an RTP session.
28 //      The MID will identify the media section and the RID will identify
29 //      the stream within the section.
30 //      RID identifiers must be unique within the media section.
31 //   2. Allows indicating further restrictions to the stream.
32 //      These restrictions are added according to the direction specified.
33 //      The direction field identifies the direction of the RTP stream packets
34 //      to which the restrictions apply. The direction is independent of the
35 //      transceiver direction and can be one of {send, recv}.
36 //      The following are some examples of these restrictions:
37 //        a. max-width, max-height, max-fps, max-br, ...
38 //        b. further restricting the codec set (from what m= section specified)
39 //
40 // Note: Indicating dependencies between streams (using depend) will not be
41 // supported, since the WG is adopting a different approach to achieve this.
42 // As of 2018-12-04, the new SVC (Scalable Video Coder) approach is still not
43 // mature enough to be implemented as part of this work.
44 // See: https://w3c.github.io/webrtc-svc/ for more details.
45 struct RidDescription final {
46   RidDescription();
47   RidDescription(const std::string& rid, RidDirection direction);
48   RidDescription(const RidDescription& other);
49   ~RidDescription();
50   RidDescription& operator=(const RidDescription& other);
51 
52   // This is currently required for unit tests of StreamParams which contains
53   // RidDescription objects and checks for equality using operator==.
54   bool operator==(const RidDescription& other) const;
55   bool operator!=(const RidDescription& other) const {
56     return !(*this == other);
57   }
58 
59   // The RID identifier that uniquely identifies the stream within the session.
60   std::string rid;
61 
62   // Specifies the direction for which the specified restrictions hold.
63   // This direction is either send or receive and is independent of the
64   // direction of the transceiver.
65   // https://tools.ietf.org/html/draft-ietf-mmusic-rid-15#section-4 :
66   // The "direction" field identifies the direction of the RTP Stream
67   // packets to which the indicated restrictions are applied.  It may be
68   // either "send" or "recv".  Note that these restriction directions are
69   // expressed independently of any "inactive", "sendonly", "recvonly", or
70   // "sendrecv" attributes associated with the media section.  It is, for
71   // example, valid to indicate "recv" restrictions on a "sendonly"
72   // stream; those restrictions would apply if, at a future point in time,
73   // the stream were changed to "sendrecv" or "recvonly".
74   RidDirection direction;
75 
76   // The list of codec payload types for this stream.
77   // It should be a subset of the payloads supported for the media section.
78   std::vector<int> payload_types;
79 
80   // Contains key-value pairs for restrictions.
81   // The keys are not validated against a known set.
82   // The meaning to infer for the values depends on each key.
83   // Examples:
84   // 1. An entry for max-width will have a value that is interpreted as an int.
85   // 2. An entry for max-bpp (bits per pixel) will have a float value.
86   // Interpretation (and validation of value) is left for the implementation.
87   // I.E. the media engines should validate values for parameters they support.
88   std::map<std::string, std::string> restrictions;
89 };
90 
91 }  // namespace cricket
92 
93 #endif  // MEDIA_BASE_RID_DESCRIPTION_H_
94