RTP Payload Format for VP8 Video
RFC 7741

Internet Engineering Task Force (IETF) P. Westin
Request for Comments: 7741 H. Lundin
Category: Standards Track Google
ISSN: 2070-1721 M. Glover
 Twitter
 J. Uberti
 F. Galligan
 Google
 March 2016
 RTP Payload Format for VP8 Video
Abstract
 This memo describes an RTP payload format for the VP8 video codec.
 The payload format has wide applicability, as it supports
 applications from low-bitrate peer-to-peer usage to high-bitrate
 video conferences.
Status of This Memo
 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF). It represents the consensus of the IETF community. It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG). Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc7741.
Copyright Notice
 Copyright (c) 2016 IETF Trust and the persons identified as the
 document authors. All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document. Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document. Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.
Westin, et al. Standards Track [Page 1]
RFC 7741 RTP Payload Format for VP8 March 2016
Table of Contents
 1. Introduction ....................................................3
 2. Conventions, Definitions, and Abbreviations .....................3
 3. Media Format Description ........................................4
 4. Payload Format ..................................................5
 4.1. RTP Header Usage ...........................................6
 4.2. VP8 Payload Descriptor .....................................7
 4.3. VP8 Payload Header ........................................11
 4.4. Aggregated and Fragmented Payloads ........................12
 4.5. Example Algorithms ........................................13
 4.5.1. Frame Reconstruction Algorithm .....................13
 4.5.2. Partition Reconstruction Algorithm .................13
 4.6. Examples of VP8 RTP Stream ................................14
 4.6.1. Key Frame in a Single RTP Packet ...................14
 4.6.2. Non-discardable VP8 Interframe in a Single
 RTP Packet; No PictureID ...........................14
 4.6.3. VP8 Partitions in Separate RTP Packets .............15
 4.6.4. VP8 Frame Fragmented across RTP Packets ............16
 4.6.5. VP8 Frame with Long PictureID ......................18
 5. Using VP8 with RPSI and SLI Feedback ...........................18
 5.1. RPSI ......................................................18
 5.2. SLI .......................................................19
 5.3. Example ...................................................19
 6. Payload Format Parameters ......................................21
 6.1. Media Type Definition .....................................21
 6.2. SDP Parameters ............................................23
 6.2.1. Mapping of Media Subtype Parameters to SDP .........23
 6.2.2. Offer/Answer Considerations ........................23
 7. Security Considerations ........................................24
 8. Congestion Control .............................................24
 9. IANA Considerations ............................................24
 10. References ....................................................25
 10.1. Normative References .....................................25
 10.2. Informative References ...................................26
 Authors' Addresses ................................................28
Westin, et al. Standards Track [Page 2]
RFC 7741 RTP Payload Format for VP8 March 2016
1. Introduction
 This memo describes an RTP payload specification applicable to the
 transmission of video streams encoded using the VP8 video codec
 [RFC6386]. The format described in this document can be used both in
 peer-to-peer and video-conferencing applications.
 VP8 is based on the decomposition of frames into square sub-blocks of
 pixels known as "macroblocks" (see Section 2 of [RFC6386]).
 Prediction of such sub-blocks using previously constructed blocks,
 and adjustment of such predictions (as well as synthesis of
 unpredicted blocks) is done using a discrete cosine transform
 (hereafter abbreviated as DCT). In one special case, however, VP8
 uses a "Walsh-Hadamard" transform (hereafter abbreviated as WHT)
 instead of a DCT. An encoded VP8 frame is divided into two or more
 partitions, as described in [RFC6386]. The first partition
 (prediction or mode) contains prediction mode parameters and motion
 vectors for all macroblocks. The remaining partitions all contain
 the quantized DCT/WHT coefficients for the residuals. There can be
 1, 2, 4, or 8 DCT/WHT partitions per frame, depending on encoder
 settings.
 In summary, the payload format described in this document enables a
 number of features in VP8, including:
 o Taking partition boundaries into consideration, to improve loss
 robustness and facilitate efficient packet-loss concealment at the
 decoder.
 o Temporal scalability.
 o Advanced use of reference frames to enable efficient error
 recovery.
 o Marking of frames that have no impact on the decoding of any other
 frame, so that these non-reference frames can be discarded in a
 server or media-aware network element if needed.
2. Conventions, Definitions, and Abbreviations
 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in [RFC2119].
Westin, et al. Standards Track [Page 3]
RFC 7741 RTP Payload Format for VP8 March 2016
 This document uses the definitions of [RFC6386]. In particular, the
 following terms are used.
 Key frames: Frames that are decoded without reference to any other
 frame in a sequence (also called intraframes and I-frames).
 Interframes: Frames that are encoded with reference to prior frames,
 specifically all prior frames up to and including the most recent
 key frame (also called prediction frames and P-frames).
 Golden and altref frames: alternate prediction frames. Blocks in an
 interframe may be predicted using blocks in the immediately
 previous frame as well as the most recent golden frame or altref
 frame. Every key frame is automatically golden and altref, and
 any interframe may optionally replace the most recent golden or
 altref frame.
 Macroblock: a square array of pixels whose Y (luminance) dimensions
 are 16x16 pixels and whose U and V (chrominance) dimensions are
 8x8 pixels.
 Two definitions from [RFC4585] are also used in this document.
 RPSI: Reference picture selection indication. A feedback message to
 let the encoder know that the decoder has correctly decoded a
 certain frame.
 SLI: Slice loss indication. A feedback message to let a decoder
 inform an encoder that it has detected the loss or corruption of
 one or several macroblocks.
3. Media Format Description
 The VP8 codec uses three different reference frames for interframe
 prediction: the previous frame, the golden frame, and the altref
 frame. Blocks in an interframe may be predicted using blocks in the
 immediately previous frame as well as the most recent golden frame or
 altref frame. Every key frame is automatically golden and altref,
 and any interframe may optionally replace the most recent golden or
 altref frame. Golden frames and altref frames may also be used to
 increase the tolerance to dropped frames. The payload specification
 in this memo has elements that enable advanced use of the reference
 frames, e.g., for improved loss robustness.
 One specific use case of the three reference frame types is temporal
 scalability. By setting up the reference hierarchy in the
 appropriate way, up to five temporal layers can be encoded. (How to
 set up the reference hierarchy for temporal scalability is not within
Westin, et al. Standards Track [Page 4]
RFC 7741 RTP Payload Format for VP8 March 2016
 the scope of this memo.) Support for temporal scalability is
 provided by the optional TL0PICIDX and TID/Y/KEYIDX fields described
 in Section 4.2. For a general description of temporal scalability
 for video coding, see [Sch07].
 Another property of the VP8 codec is that it applies data
 partitioning to the encoded data. Thus, an encoded VP8 frame can be
 divided into two or more partitions, as described in "VP8 Data Format
 and Decoding Guide" [RFC6386]. The first partition (prediction or
 mode) contains prediction mode parameters and motion vectors for all
 macroblocks. The remaining partitions all contain the transform
 coefficients for the residuals. The first partition is decodable
 without the remaining residual partitions. The subsequent partitions
 may be useful even if some part of the frame is lost. Accordingly,
 this document RECOMMENDS that the frame be packetized by the sender
 with each data partition in a separate packet or packets. This may
 be beneficial for decoder-side error concealment, and the payload
 format described in Section 4 provides fields that allow the
 partitions to be identified even if the first partition is not
 available. The sender can, alternatively, aggregate the data
 partitions into a single data stream and, optionally, split it into
 several packets without consideration of the partition boundaries.
 The receiver can use the length information in the first partition to
 identify the partitions during decoding.
 The format specification is described in Section 4. In Section 5, a
 method to acknowledge receipt of reference frames using RTCP
 techniques is described.
 The payload partitioning and the acknowledging method both serve as
 motivation for three of the fields included in the payload format:
 the "PID", "1st partition size", and "PictureID" fields. The ability
 to encode a temporally scalable stream motivates the "TL0PICIDX" and
 "TID" fields.
4. Payload Format
 This section describes how the encoded VP8 bitstream is encapsulated
 in RTP. To handle network losses, usage of RTP/AVPF [RFC4585] is
 RECOMMENDED. All integer fields in the specifications are encoded as
 unsigned integers in network octet order.
Westin, et al. Standards Track [Page 5]
RFC 7741 RTP Payload Format for VP8 March 2016
4.1. RTP Header Usage
 The general RTP payload format for VP8 is depicted below.
 0 1 2 3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |V=2|P|X| CC |M| PT | sequence number |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | timestamp |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | synchronization source (SSRC) identifier |
 +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
 | contributing source (CSRC) identifiers |
 | .... |
 +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
 | VP8 payload descriptor (integer #octets) |
 : :
 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | : VP8 payload header (3 octets) |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | VP8 pyld hdr : |
 +-+-+-+-+-+-+-+-+ |
 : Octets 4..N of VP8 payload :
 | |
 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | : OPTIONAL RTP padding |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 The VP8 payload descriptor and VP8 payload header will be described
 in Sections 4.2 and 4.3. OPTIONAL RTP padding MUST NOT be included
 unless the P bit is set. The figure specifically shows the format
 for the first packet in a frame. Subsequent packets will not contain
 the VP8 payload header and will have later octets in the frame
 payload.
 Figure 1
 Marker bit (M): MUST be set for the very last packet of each encoded
 frame in line with the normal use of the M bit in video formats.
 This enables a decoder to finish decoding the picture, where it
 otherwise may need to wait for the next packet to explicitly know
 that the frame is complete.
 Payload type (PT): The assignment of an RTP payload type for this
 packet format is outside the scope of this document and will not
 be specified here.
Westin, et al. Standards Track [Page 6]
RFC 7741 RTP Payload Format for VP8 March 2016
 Timestamp: The RTP timestamp indicates the time when the frame was
 sampled. The granularity of the clock is 90 kHz, so a delta of 1
 represents 1/90,000 of a second.
 The remaining RTP Fixed Header Fields (V, P, X, CC, sequence
 number, SSRC, and CSRC identifiers) are used as specified in
 Section 5.1 of [RFC3550].
4.2. VP8 Payload Descriptor
 The first octets after the RTP header are the VP8 payload descriptor,
 with the following structure. The single-octet version of the
 PictureID is illustrated to the left (M bit set to 0), while the
 dual-octet version (M bit set to 1) is shown to the right.
 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 |X|R|N|S|R| PID | (REQUIRED) |X|R|N|S|R| PID | (REQUIRED)
 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 X: |I|L|T|K| RSV | (OPTIONAL) X: |I|L|T|K| RSV | (OPTIONAL)
 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 I: |M| PictureID | (OPTIONAL) I: |M| PictureID | (OPTIONAL)
 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 L: | TL0PICIDX | (OPTIONAL) | PictureID |
 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 T/K: |TID|Y| KEYIDX | (OPTIONAL) L: | TL0PICIDX | (OPTIONAL)
 +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
 T/K: |TID|Y| KEYIDX | (OPTIONAL)
 +-+-+-+-+-+-+-+-+
 Figure 2
 X: Extended control bits present. When set to 1, the extension octet
 MUST be provided immediately after the mandatory first octet. If
 the bit is zero, all optional fields MUST be omitted. Note: this
 X bit is not to be confused with the X bit in the RTP header.
 R: Bit reserved for future use. MUST be set to 0 and MUST be ignored
 by the receiver.
 N: Non-reference frame. When set to 1, the frame can be discarded
 without affecting any other future or past frames. If the
 reference status of the frame is unknown, this bit SHOULD be set
 to 0 to avoid discarding frames needed for reference.
 Informative note: This document does not describe how to
 determine if an encoded frame is non-reference. The reference
 status of an encoded frame is preferably provided from the
 encoder implementation.
Westin, et al. Standards Track [Page 7]
RFC 7741 RTP Payload Format for VP8 March 2016
 S: Start of VP8 partition. SHOULD be set to 1 when the first payload
 octet of the RTP packet is the beginning of a new VP8 partition,
 and MUST NOT be 1 otherwise. The S bit MUST be set to 1 for the
 first packet of each encoded frame.
 PID: Partition index. Denotes to which VP8 partition the first
 payload octet of the packet belongs. The first VP8 partition
 (containing modes and motion vectors) MUST be labeled with PID =
 0. PID SHOULD be incremented by 1 for each subsequent partition,
 but it MAY be kept at 0 for all packets. PID cannot be larger
 than 7. If more than one packet in an encoded frame contains the
 same PID, the S bit MUST NOT be set for any packet other than the
 first packet with that PID.
 When the X bit is set to 1 in the first octet, the Extended Control
 Bits field octet MUST be provided as the second octet. If the X bit
 is 0, the Extended Control Bits field octet MUST NOT be present, and
 no extensions (I, L, T, or K) are permitted.
 I: PictureID present. When set to 1, the PictureID MUST be present
 after the extension bit field and specified as below. Otherwise,
 PictureID MUST NOT be present.
 L: TL0PICIDX present. When set to 1, the TL0PICIDX MUST be present
 and specified as below, and the T bit MUST be set to 1.
 Otherwise, TL0PICIDX MUST NOT be present.
 T: TID present. When set to 1, the TID/Y/KEYIDX octet MUST be
 present. The TID|Y part of the octet MUST be specified as below.
 If K (below) is set to 1 but T is set to 0, the TID/Y/KEYIDX octet
 MUST be present, but the TID field MUST be ignored. If neither T
 nor K is set to 1, the TID/Y/KEYIDX octet MUST NOT be present.
 K: KEYIDX present. When set to 1, the TID/Y/KEYIDX octet MUST be
 present. The KEYIDX part of the octet MUST be specified as below.
 If T (above) is set to 1 but K is set to 0, the TID/Y/KEYIDX octet
 MUST be present, but the KEYIDX field MUST be ignored. If neither
 T nor K is set to 1, the TID/Y/KEYIDX octet MUST NOT be present.
 RSV: Bits reserved for future use. MUST be set to 0 and MUST be
 ignored by the receiver.
Westin, et al. Standards Track [Page 8]
RFC 7741 RTP Payload Format for VP8 March 2016
 After the extension bit field follow the extension data fields that
 are enabled.
 The PictureID extension: If the I bit is set to 1, the PictureID
 extension field MUST be present, and it MUST NOT be present
 otherwise. The field consists of two parts:
 M: The most significant bit of the first octet is an extension
 flag. If M is set, the remainder of the PictureID field MUST
 contain 15 bits, else it MUST contain 7 bits. Note: this M bit
 is not to be confused with the M bit in the RTP header.
 PictureID: 7 or 15 bits (shown left and right, respectively, in
 Figure 2) not including the M bit. This is a running index of
 the frames, which MAY start at a random value, MUST increase by
 1 for each subsequent frame, and MUST wrap to 0 after reaching
 the maximum ID (all bits set). The 7 or 15 bits of the
 PictureID go from most significant to least significant,
 beginning with the first bit after the M bit. The sender
 chooses a 7- or 15-bit index and sets the M bit accordingly.
 The receiver MUST NOT assume that the number of bits in
 PictureID stays the same through the session. Having sent a
 7-bit PictureID with all bits set to 1, the sender may either
 wrap the PictureID to 0 or extend to 15 bits and continue
 incrementing.
 The TL0PICIDX extension: If the L bit is set to 1, the TL0PICIDX
 extension field MUST be present, and it MUST NOT be present
 otherwise. The field consists of one part:
 TL0PICIDX: 8 bits temporal level zero index. TL0PICIDX is a
 running index for the temporal base layer frames, i.e., the
 frames with TID set to 0. If TID is larger than 0, TL0PICIDX
 indicates on which base-layer frame the current image depends.
 TL0PICIDX MUST be incremented when TID is 0. The index MAY
 start at a random value, and it MUST wrap to 0 after reaching
 the maximum number 255. Use of TL0PICIDX depends on the
 presence of TID. Therefore, it is RECOMMENDED that the TID be
 used whenever TL0PICIDX is.
 The TID/Y/KEYIDX extension: If either of the T or K bits are set to
 1, the TID/Y/KEYIDX extension field MUST be present. It MUST NOT
 be present if both T and K are zero. The field consists of three
 parts:
 TID: 2 bits temporal-layer index. The TID field MUST be ignored
 by the receiver when the T bit is set equal to 0. The TID
 field indicates which temporal layer the packet represents.
Westin, et al. Standards Track [Page 9]
RFC 7741 RTP Payload Format for VP8 March 2016
 The lowest layer, i.e., the base layer, MUST have the TID set
 to 0. Higher layers SHOULD increment the TID according to
 their position in the layer hierarchy.
 Y: 1 layer sync bit. The Y bit SHOULD be set to 1 if the current
 frame depends only on the base layer (TID = 0) frame with
 TL0PICIDX equal to that of the current frame. The Y bit MUST
 be set to 0 if the current frame depends on any other frame
 than the base layer (TID = 0) frame with TL0PICIDX equal to
 that of the current frame. Additionally, the Y bit MUST be set
 to 0 if any frame following the current frame depends on a non-
 base-layer frame older than the base-layer frame with TL0PICIDX
 equal to that of the current frame. If the Y bit is set when
 the T bit is equal to 0, the current frame MUST only depend on
 a past base-layer (TID=0) key frame as signaled by a change in
 the KEYIDX field. Additionally, this frame MUST NOT depend on
 any of the three codec buffers (as defined by [RFC6386]) that
 have been updated since the last time the KEYIDX field was
 changed.
 Informative note: This document does not describe how to
 determine the dependency status for a frame; this information
 is preferably provided from the encoder implementation. In the
 case of unknown status, the Y bit can safely be set to 0.
 KEYIDX: 5 bits temporal key frame index. The KEYIDX field MUST
 be ignored by the receiver when the K bit is set equal to 0.
 The KEYIDX field is a running index for key frames. KEYIDX MAY
 start at a random value, and it MUST wrap to 0 after reaching
 the maximum number 31. When in use, the KEYIDX SHOULD be
 present for both key frames and interframes. The sender MUST
 increment KEYIDX for key frames that convey parameter updates
 critical to the interpretation of subsequent frames, and it
 SHOULD leave the KEYIDX unchanged for key frames that do not
 contain these critical updates. If the KEYIDX is present, a
 receiver SHOULD NOT decode an interframe if it has not received
 and decoded a key frame with the same KEYIDX after the last
 KEYIDX wraparound.
 Informative note: This document does not describe how to
 determine if a key frame updates critical parameters; this
 information is preferably provided from the encoder
 implementation. A sender that does not have this information
 may either omit the KEYIDX field (set K equal to 0) or
 increment the KEYIDX on every key frame. The benefit with the
 latter is that any key-frame loss will be detected by the
 receiver, which can signal for re-transmission or request a new
 key frame.
Westin, et al. Standards Track [Page 10]
RFC 7741 RTP Payload Format for VP8 March 2016
 Informative note: Implementations doing splicing of VP8 streams will
 have to make sure the rules for incrementing TL0PICIDX and KEYIDX
 are obeyed across the splice. This will likely require rewriting
 values of TL0PICIDX and KEYIDX after the splice.
4.3. VP8 Payload Header
 The beginning of an encoded VP8 frame is referred to as an
 "uncompressed data chunk" in Section 9.1 of [RFC6386], and it also
 serves as a payload header in this RTP format. The codec bitstream
 format specifies two different variants of the uncompressed data
 chunk: a 3-octet version for interframes and a 10-octet version for
 key frames. The first 3 octets are common to both variants. In the
 case of a key frame, the remaining 7 octets are considered to be part
 of the remaining payload in this RTP format. Note that the header is
 present only in packets that have the S bit equal to one and the PID
 equal to zero in the payload descriptor. Subsequent packets for the
 same frame do not carry the payload header.
 The length of the first partition can always be obtained from the
 first partition-size parameter in the VP8 payload header. The VP8
 bitstream format [RFC6386] specifies that if multiple DCT/WHT
 partitions are produced, the location of each partition start is
 found at the end of the first (prediction or mode) partition. In
 this RTP payload specification, the location offsets are considered
 to be part of the first partition.
 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+
 |Size0|H| VER |P|
 +-+-+-+-+-+-+-+-+
 | Size1 |
 +-+-+-+-+-+-+-+-+
 | Size2 |
 +-+-+-+-+-+-+-+-+
 | Octets 4..N of|
 | VP8 payload |
 : :
 +-+-+-+-+-+-+-+-+
 | OPTIONAL RTP |
 | padding |
 : :
 +-+-+-+-+-+-+-+-+
 Figure 3
Westin, et al. Standards Track [Page 11]
RFC 7741 RTP Payload Format for VP8 March 2016
 A packetizer needs access to the P bit. The other fields are defined
 in [RFC6386], Section 9.1, and their meanings do not influence the
 packetization process. None of these fields are modified by the
 packetization process.
 P: Inverse key frame flag. When set to 0, the current frame is a key
 frame. When set to 1, the current frame is an interframe.
 Defined in [RFC6386]
4.4. Aggregated and Fragmented Payloads
 An encoded VP8 frame can be divided into two or more partitions, as
 described in Section 1. It is OPTIONAL for a packetizer implementing
 this RTP specification to pay attention to the partition boundaries
 within an encoded frame. If packetization of a frame is done without
 considering the partition boundaries, the PID field MAY be set to 0
 for all packets and the S bit MUST NOT be set to 1 for any other
 packet than the first.
 If the preferred usage suggested in Section 3 is followed, with each
 packet carrying data from exactly one partition, the S bit and PID
 fields described in Section 4.2 SHOULD be used to indicate what the
 packet contains. The PID field should indicate to which partition
 the first octet of the payload belongs and the S bit indicates that
 the packet starts on a new partition.
 If the packetizer does not pay attention to the partition boundaries,
 one packet can contain a fragment of a partition, a complete
 partition, or an aggregate of fragments and partitions. There is no
 explicit signaling of partition boundaries in the payload, and the
 partition lengths at the end of the first partition have to be used
 to identify the boundaries. Partitions MUST be aggregated in
 decoding order. Two fragments from different partitions MAY be
 aggregated into the same packet along with one or more complete
 partitions.
 In all cases, the payload of a packet MUST contain data from only one
 video frame. Consequently, the set of packets carrying the data from
 a particular frame will contain exactly one VP8 Payload Header (see
 Section 4.3) carried in the first packet of the frame. The last, or
 only, packet carrying data for the frame MUST have the M bit set in
 the RTP header.
Westin, et al. Standards Track [Page 12]
RFC 7741 RTP Payload Format for VP8 March 2016
4.5. Example Algorithms
4.5.1. Frame Reconstruction Algorithm
 Example of frame reconstruction algorithm.
 1: Collect all packets with a given RTP timestamp.
 2: Go through packets in order, sorted by sequence numbers, if
 packets are missing, send NACK as defined in [RFC4585] or decode
 with missing partitions, see Section 4.5.2 below.
 3: A frame is complete if the frame has no missing sequence numbers,
 the first packet in the frame contains S=1 with partId=0 and the
 last packet in the frame has the marker bit set.
4.5.2. Partition Reconstruction Algorithm
 Example of partition reconstruction algorithm. The algorithm only
 applies for the RECOMMENDED use case with partitions in separate
 packets.
 1: Scan for the start of a new partition; S=1.
 2: Continue scan to detect end of partition; hence, a new S=1
 (previous packet was the end of the partition) is found or the
 marker bit is set. If a loss is detected before the end of the
 partition, abandon all packets in this partition and continue the
 scan repeating from step 1.
 3: Store the packets in the complete partition, continue the scan
 repeating from step 1 until end of frame is reached.
 4: Send all complete partitions to the decoder. If no complete
 partition is found discard the whole frame.
Westin, et al. Standards Track [Page 13]
RFC 7741 RTP Payload Format for VP8 March 2016
4.6. Examples of VP8 RTP Stream
 A few examples of how the VP8 RTP payload can be used are included
 below.
4.6.1. Key Frame in a Single RTP Packet
 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+
 | RTP header |
 | M = 1 |
 +-+-+-+-+-+-+-+-+
 |1|0|0|1|0|0 0 0| X = 1; S = 1; PID = 0
 +-+-+-+-+-+-+-+-+
 |1|0|0|0|0 0 0 0| I = 1
 +-+-+-+-+-+-+-+-+
 |0 0 0 1 0 0 0 1| PictureID = 17
 +-+-+-+-+-+-+-+-+
 |Size0|1| VER |0| P = 0
 +-+-+-+-+-+-+-+-+
 | Size1 |
 +-+-+-+-+-+-+-+-+
 | Size2 |
 +-+-+-+-+-+-+-+-+
 | VP8 payload |
 +-+-+-+-+-+-+-+-+
4.6.2. Non-discardable VP8 Interframe in a Single RTP Packet; No
 PictureID
 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+
 | RTP header |
 | M = 1 |
 +-+-+-+-+-+-+-+-+
 |0|0|0|1|0|0 0 0| X = 0; S = 1; PID = 0
 +-+-+-+-+-+-+-+-+
 |Size0|1| VER |1| P = 1
 +-+-+-+-+-+-+-+-+
 | Size1 |
 +-+-+-+-+-+-+-+-+
 | Size2 |
 +-+-+-+-+-+-+-+-+
 | VP8 payload |
 +-+-+-+-+-+-+-+-+
Westin, et al. Standards Track [Page 14]
RFC 7741 RTP Payload Format for VP8 March 2016
4.6.3. VP8 Partitions in Separate RTP Packets
 First RTP packet; complete first partition.
 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+
 | RTP header |
 | M = 0 |
 +-+-+-+-+-+-+-+-+
 |1|0|0|1|0|0 0 0| X = 1; S = 1; PID = 0
 +-+-+-+-+-+-+-+-+
 |1|0|0|0|0 0 0 0| I = 1
 +-+-+-+-+-+-+-+-+
 |0 0 0 1 0 0 0 1| PictureID = 17
 +-+-+-+-+-+-+-+-+
 |Size0|1| VER |1| P = 1
 +-+-+-+-+-+-+-+-+
 | Size1 |
 +-+-+-+-+-+-+-+-+
 | Size2 |
 +-+-+-+-+-+-+-+-+
 | Octets 4..L of|
 | first VP8 |
 | partition |
 : :
 +-+-+-+-+-+-+-+-+
 Second RTP packet; complete second partition.
 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+
 | RTP header |
 | M = 1 |
 +-+-+-+-+-+-+-+-+
 |1|0|0|1|0|0 0 1| X = 1; S = 1; PID = 1
 +-+-+-+-+-+-+-+-+
 |1|0|0|0|0 0 0 0| I = 1
 +-+-+-+-+-+-+-+-+
 |0 0 0 1 0 0 0 1| PictureID = 17
 +-+-+-+-+-+-+-+-+
 | Remaining VP8 |
 | partitions |
 : :
 +-+-+-+-+-+-+-+-+
Westin, et al. Standards Track [Page 15]
RFC 7741 RTP Payload Format for VP8 March 2016
4.6.4. VP8 Frame Fragmented across RTP Packets
 First RTP packet; complete first partition.
 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+
 | RTP header |
 | M = 0 |
 +-+-+-+-+-+-+-+-+
 |1|0|0|1|0|0 0 0| X = 1; S = 1; PID = 0
 +-+-+-+-+-+-+-+-+
 |1|0|0|0|0 0 0 0| I = 1
 +-+-+-+-+-+-+-+-+
 |0 0 0 1 0 0 0 1| PictureID = 17
 +-+-+-+-+-+-+-+-+
 |Size0|1| VER |1| P = 1
 +-+-+-+-+-+-+-+-+
 | Size1 |
 +-+-+-+-+-+-+-+-+
 | Size2 |
 +-+-+-+-+-+-+-+-+
 | Complete |
 | first |
 | partition |
 : :
 +-+-+-+-+-+-+-+-+
 Second RTP packet; first fragment of second partition.
 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+
 | RTP header |
 | M = 0 |
 +-+-+-+-+-+-+-+-+
 |1|0|0|1|0|0 0 1| X = 1; S = 1; PID = 1
 +-+-+-+-+-+-+-+-+
 |1|0|0|0|0 0 0 0| I = 1
 +-+-+-+-+-+-+-+-+
 |0 0 0 1 0 0 0 1| PictureID = 17
 +-+-+-+-+-+-+-+-+
 | First fragment|
 | of second |
 | partition |
 : :
 +-+-+-+-+-+-+-+-+
Westin, et al. Standards Track [Page 16]
RFC 7741 RTP Payload Format for VP8 March 2016
 Third RTP packet; second fragment of second partition.
 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+
 | RTP header |
 | M = 0 |
 +-+-+-+-+-+-+-+-+
 |1|0|0|0|0|0 0 1| X = 1; S = 0; PID = 1
 +-+-+-+-+-+-+-+-+
 |1|0|0|0|0 0 0 0| I = 1
 +-+-+-+-+-+-+-+-+
 |0 0 0 1 0 0 0 1| PictureID = 17
 +-+-+-+-+-+-+-+-+
 | Mid fragment |
 | of second |
 | partition |
 : :
 +-+-+-+-+-+-+-+-+
 Fourth RTP packet; last fragment of second partition.
 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+
 | RTP header |
 | M = 1 |
 +-+-+-+-+-+-+-+-+
 |1|0|0|0|0|0 0 1| X = 1; S = 0; PID = 1
 +-+-+-+-+-+-+-+-+
 |1|0|0|0|0 0 0 0| I = 1
 +-+-+-+-+-+-+-+-+
 |0 0 0 1 0 0 0 1| PictureID = 17
 +-+-+-+-+-+-+-+-+
 | Last fragment |
 | of second |
 | partition |
 : :
 +-+-+-+-+-+-+-+-+
Westin, et al. Standards Track [Page 17]
RFC 7741 RTP Payload Format for VP8 March 2016
4.6.5. VP8 Frame with Long PictureID
 PictureID = 4711 =わ 001001001100111 binary (first 7 bits: 0010010,
 last 8 bits: 01100111).
 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+
 | RTP header |
 | M = 1 |
 +-+-+-+-+-+-+-+-+
 |1|0|0|1|0|0 0 0| X = 1; S = 1; PID = 0
 +-+-+-+-+-+-+-+-+
 |1|0|0|0|0 0 0 0| I = 1;
 +-+-+-+-+-+-+-+-+
 |1 0 0 1 0 0 1 0| Long PictureID flag = 1
 |0 1 1 0 0 1 1 1| PictureID = 4711
 +-+-+-+-+-+-+-+-+
 |Size0|1| VER |1|
 +-+-+-+-+-+-+-+-+
 | Size1 |
 +-+-+-+-+-+-+-+-+
 | Size2 |
 +-+-+-+-+-+-+-+-+
 | Octets 4..N of|
 | VP8 payload |
 : :
 +-+-+-+-+-+-+-+-+
5. Using VP8 with RPSI and SLI Feedback
 The VP8 payload descriptor defined in Section 4.2 contains an
 optional PictureID parameter. This parameter is included mainly to
 enable use of reference picture selection indication (RPSI) and slice
 loss indication (SLI), both defined in [RFC4585].
5.1. RPSI
 The RPSI is a payload-specific feedback message defined within the
 RTCP-based feedback format. The RPSI message is generated by a
 receiver and can be used in two ways. Either it can signal a
 preferred reference picture when a loss has been detected by the
 decoder -- preferably then a reference that the decoder knows is
 perfect -- or it can be used as positive feedback information to
 acknowledge correct decoding of certain reference pictures. The
 positive-feedback method is useful for VP8 used for point-to-point
 (unicast) communication. The use of RPSI for VP8 is preferably
 combined with a special update pattern of the codec's two special
 reference frames -- the golden frame and the altref frame -- in which
Westin, et al. Standards Track [Page 18]
RFC 7741 RTP Payload Format for VP8 March 2016
 they are updated in an alternating leapfrog fashion. When a receiver
 has received and correctly decoded a golden or altref frame, and that
 frame has a PictureID in the payload descriptor, the receiver can
 acknowledge this simply by sending an RPSI message back to the
 sender. The message body (i.e., the "native RPSI bit string" in
 [RFC4585]) is simply the PictureID of the received frame.
5.2. SLI
 The SLI is another payload-specific feedback message defined within
 the RTCP-based feedback format. The SLI message is generated by the
 receiver when a loss or corruption is detected in a frame. The
 format of the SLI message is as follows [RFC4585]:
 0 1 2 3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | First | Number | PictureID |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Figure 4
 Here, First is the macroblock address (in scan order) of the first
 lost block and Number is the number of lost blocks, as defined in
 [RFC4585]. PictureID is the six least significant bits of the codec-
 specific picture identifier in which the loss or corruption has
 occurred. For VP8, this codec-specific identifier is naturally the
 PictureID of the current frame, as read from the payload descriptor.
 If the payload descriptor of the current frame does not have a
 PictureID, the receiver MAY send the last received PictureID+1 in the
 SLI message. The receiver MAY set the First parameter to 0, and the
 Number parameter to the total number of macroblocks per frame, even
 though only part of the frame is corrupted. When the sender receives
 an SLI message, it can make use of the knowledge from the latest
 received RPSI message. Knowing that the last golden or altref frame
 was successfully received, it can encode the next frame with
 reference to that established reference.
5.3. Example
 The use of RPSI and SLI is best illustrated in an example. In this
 example, the encoder may not update the altref frame until the last
 sent golden frame has been acknowledged with an RPSI message. If an
 update is not received within some time, a new golden frame update is
 sent instead. Once the new golden frame is established and
 acknowledged, the same rule applies when updating the altref frame.
Westin, et al. Standards Track [Page 19]
RFC 7741 RTP Payload Format for VP8 March 2016
 +-------+-------------------+-------------------------+-------------+
 | Event | Sender | Receiver | Established |
 | | | | reference |
 +-------+-------------------+-------------------------+-------------+
 | 1000 | Send golden frame | | |
 | | PictureID = 0 | | |
 | | | | |
 | | | Receive and decode | |
 | | | golden frame | |
 | | | | |
 | 1001 | | Send RPSI(0) | |
 | | | | |
 | 1002 | Receive RPSI(0) | | golden |
 | | | | |
 | ... | (sending regular | | |
 | | frames) | | |
 | | | | |
 | 1100 | Send altref frame | | |
 | | PictureID = 100 | | |
 | | | | |
 | | | Altref corrupted or | golden |
 | | | lost | |
 | | | | |
 | 1101 | | Send SLI(100) | golden |
 | | | | |
 | 1102 | Receive SLI(100) | | |
 | | | | |
 | 1103 | Send frame with | | |
 | | reference to | | |
 | | golden | | |
 | | | | |
 | | | Receive and decode | golden |
 | | | frame (decoder state | |
 | | | restored) | |
 | | | | |
 | ... | (sending regular | | |
 | | frames) | | |
 | | | | |
 | 1200 | Send altref frame | | |
 | | PictureID = 200 | | |
 | | | | |
 | | | Receive and decode | golden |
 | | | altref frame | |
 | | | | |
 | 1201 | | Send RPSI(200) | |
 | | | | |
 | 1202 | Receive RPSI(200) | | altref |
 | | | | |
Westin, et al. Standards Track [Page 20]
RFC 7741 RTP Payload Format for VP8 March 2016
 | ... | (sending regular | | |
 | | frames) | | |
 | | | | |
 | 1300 | Send golden frame | | |
 | | PictureID = 300 | | |
 | | | | |
 | | | Receive and decode | altref |
 | | | golden frame | |
 | | | | |
 | 1301 | | Send RPSI(300) | altref |
 | | | | |
 | 1302 | RPSI lost | | |
 | | | | |
 | 1400 | Send golden frame | | |
 | | PictureID = 400 | | |
 | | | | |
 | | | Receive and decode | altref |
 | | | golden frame | |
 | | | | |
 | 1401 | | Send RPSI(400) | |
 | | | | |
 | 1402 | Receive RPSI(400) | | golden |
 +-------+-------------------+-------------------------+-------------+
 Table 1: Example Signaling between Sender and Receiver
 Note that the scheme is robust to loss of the feedback messages. If
 the RPSI is lost, the sender will try to update the golden (or
 altref) again after a while, without releasing the established
 reference. Also, if an SLI is lost, the receiver can keep sending
 SLI messages at any interval allowed by the RTCP sending timing
 restrictions as specified in [RFC4585], as long as the picture is
 corrupted.
6. Payload Format Parameters
 This payload format has two optional parameters.
6.1. Media Type Definition
 This registration is done using the template defined in [RFC6838] and
 following [RFC4855].
 Type name: video
 Subtype name: VP8
 Required parameters: None.
Westin, et al. Standards Track [Page 21]
RFC 7741 RTP Payload Format for VP8 March 2016
 Optional parameters:
 These parameters are used to signal the capabilities of a receiver
 implementation. If the implementation is willing to receive
 media, both parameters MUST be provided. These parameters MUST
 NOT be used for any other purpose.
 max-fr: The value of max-fr is an integer indicating the maximum
 frame rate in units of frames per second that the decoder is
 capable of decoding.
 max-fs: The value of max-fs is an integer indicating the maximum
 frame size in units of macroblocks that the decoder is capable
 of decoding.
 The decoder is capable of decoding this frame size as long as
 the width and height of the frame in macroblocks are less than
 int(sqrt(max-fs * 8)). For instance, a max-fs of 1200 (capable
 of supporting 640x480 resolution) will support widths and
 heights up to 1552 pixels (97 macroblocks).
 Encoding considerations:
 This media type is framed in RTP and contains binary data; see
 Section 4.8 of [RFC6838].
 Security considerations: See Section 7 of RFC 7741.
 Interoperability considerations: None.
 Published specification: VP8 bitstream format [RFC6386] and RFC
 7741.
 Applications that use this media type:
 For example: Video over IP, video conferencing.
 Fragment identifier considerations: N/A.
 Additional information: None.
 Person & email address to contact for further information:
 Patrik Westin, patrik.westin@gmail.com
 Intended usage: COMMON
 Restrictions on usage:
 This media type depends on RTP framing, and hence it is only
 defined for transfer via RTP [RFC3550].
Westin, et al. Standards Track [Page 22]
RFC 7741 RTP Payload Format for VP8 March 2016
 Author: Patrik Westin, patrik.westin@gmail.com
 Change controller:
 IETF Payload Working Group delegated from the IESG.
6.2. SDP Parameters
 The receiver MUST ignore any fmtp parameter unspecified in this memo.
6.2.1. Mapping of Media Subtype Parameters to SDP
 The media type video/VP8 string is mapped to fields in the Session
 Description Protocol (SDP) [RFC4566] as follows:
 o The media name in the "m=" line of SDP MUST be video.
 o The encoding name in the "a=rtpmap" line of SDP MUST be VP8 (the
 media subtype).
 o The clock rate in the "a=rtpmap" line MUST be 90000.
 o The parameters "max-fs" and "max-fr" MUST be included in the
 "a=fmtp" line if the SDP is used to declare receiver capabilities.
 These parameters are expressed as a media subtype string, in the
 form of a semicolon-separated list of parameter=value pairs.
6.2.1.1. Example
 An example of media representation in SDP is as follows:
 m=video 49170 RTP/AVPF 98
 a=rtpmap:98 VP8/90000
 a=fmtp:98 max-fr=30; max-fs=3600;
6.2.2. Offer/Answer Considerations
 The VP8 codec offers a decode complexity that is roughly linear with
 the number of pixels encoded. The parameters "max-fr" and "max-fs"
 are defined in Section 6.1, where the macroblock size is 16x16 pixels
 as defined in [RFC6386], the max-fs and max-fr parameters MUST be
 used to establish these limits.
Westin, et al. Standards Track [Page 23]
RFC 7741 RTP Payload Format for VP8 March 2016
7. Security Considerations
 RTP packets using the payload format defined in this specification
 are subject to the security considerations discussed in the RTP
 specification [RFC3550], and in any applicable RTP profile such as
 RTP/AVP [RFC3551], RTP/AVPF [RFC4585], RTP/SAVP [RFC3711], or RTP/
 SAVPF [RFC5124]. However, as "Securing the RTP Protocol Framework:
 Why RTP Does Not Mandate a Single Media Security Solution" [RFC7202]
 discusses, it is not an RTP payload format's responsibility to
 discuss or mandate what solutions are used to meet the basic security
 goals like confidentiality, integrity, and source authenticity for
 RTP in general. This responsibility lays on anyone using RTP in an
 application. They can find guidance on available security mechanisms
 and important considerations in "Options for Securing RTP Sessions"
 [RFC7201]. Applications SHOULD use one or more appropriate strong
 security mechanisms. The rest of this security consideration section
 discusses the security impacting properties of the payload format
 itself.
 This RTP payload format and its media decoder do not exhibit any
 significant difference in the receiver-side computational complexity
 for packet processing and, thus, are unlikely to pose a denial-of-
 service threat due to the receipt of pathological data. Nor does the
 RTP payload format contain any active content.
8. Congestion Control
 Congestion control for RTP SHALL be used in accordance with RFC 3550
 [RFC3550] and with any applicable RTP profile; e.g., RFC 3551
 [RFC3551]. The congestion control mechanism can, in a real-time
 encoding scenario, adapt the transmission rate by instructing the
 encoder to encode at a certain target rate. Media-aware network
 elements MAY use the information in the VP8 payload descriptor in
 Section 4.2 to identify non-reference frames and discard them in
 order to reduce network congestion. Note that discarding of non-
 reference frames cannot be done if the stream is encrypted (because
 the non-reference marker is encrypted).
9. IANA Considerations
 The IANA has registered a media type as described in Section 6.1.
Westin, et al. Standards Track [Page 24]
RFC 7741 RTP Payload Format for VP8 March 2016
10. References
10.1. Normative References
 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
 Requirement Levels", BCP 14, RFC 2119,
 DOI 10.17487/RFC2119, March 1997,
 <http://www.rfc-editor.org/info/rfc2119>.
 [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
 Jacobson, "RTP: A Transport Protocol for Real-Time
 Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
 July 2003, <http://www.rfc-editor.org/info/rfc3550>.
 [RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
 Video Conferences with Minimal Control", STD 65, RFC 3551,
 DOI 10.17487/RFC3551, July 2003,
 <http://www.rfc-editor.org/info/rfc3551>.
 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
 Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
 July 2006, <http://www.rfc-editor.org/info/rfc4566>.
 [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
 "Extended RTP Profile for Real-time Transport Control
 Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
 DOI 10.17487/RFC4585, July 2006,
 <http://www.rfc-editor.org/info/rfc4585>.
 [RFC4855] Casner, S., "Media Type Registration of RTP Payload
 Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007,
 <http://www.rfc-editor.org/info/rfc4855>.
 [RFC6386] Bankoski, J., Koleszar, J., Quillio, L., Salonen, J.,
 Wilkins, P., and Y. Xu, "VP8 Data Format and Decoding
 Guide", RFC 6386, DOI 10.17487/RFC6386, November 2011,
 <http://www.rfc-editor.org/info/rfc6386>.
 [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
 Specifications and Registration Procedures", BCP 13,
 RFC 6838, DOI 10.17487/RFC6838, January 2013,
 <http://www.rfc-editor.org/info/rfc6838>.
Westin, et al. Standards Track [Page 25]
RFC 7741 RTP Payload Format for VP8 March 2016
10.2. Informative References
 [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
 Norrman, "The Secure Real-time Transport Protocol (SRTP)",
 RFC 3711, DOI 10.17487/RFC3711, March 2004,
 <http://www.rfc-editor.org/info/rfc3711>.
 [RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for
 Real-time Transport Control Protocol (RTCP)-Based Feedback
 (RTP/SAVPF)", RFC 5124, DOI 10.17487/RFC5124, February
 2008, <http://www.rfc-editor.org/info/rfc5124>.
 [RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP
 Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014,
 <http://www.rfc-editor.org/info/rfc7201>.
 [RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP
 Framework: Why RTP Does Not Mandate a Single Media
 Security Solution", RFC 7202, DOI 10.17487/RFC7202, April
 2014, <http://www.rfc-editor.org/info/rfc7202>.
 [Sch07] Schwarz, H., Marpe, D., and T. Wiegand, "Overview of the
 Scalable Video Coding Extension of the H.264/AVC
 Standard", IEEE Transactions on Circuits and Systems for
 Video Technology, Volume 17: Issue 9,
 DOI 10.1109/TCSVT.2007.905532, September 2007,
 <http://dx.doi.org/10.1109/TCSVT.2007.905532>.
Westin, et al. Standards Track [Page 26]
RFC 7741 RTP Payload Format for VP8 March 2016
Authors' Addresses
 Patrik Westin
 Google, Inc.
 1600 Amphitheatre Parkway
 Mountain View, CA 94043
 United States
 Email: patrik.westin@gmail.com
 Henrik F Lundin
 Google, Inc.
 Kungsbron 2
 Stockholm 11122
 Sweden
 Email: hlundin@google.com
 Michael Glover
 Twitter Boston
 10 Hemlock Way
 Durham, NH 03824
 United States
 Email: michaelglover262@gmail.com
 Justin Uberti
 Google, Inc.
 747 6th Street South
 Kirkland, WA 98033
 United States
 Email: justin@uberti.name
 Frank Galligan
 Google, Inc.
 1600 Amphitheatre Parkway
 Mountain View, CA 94043
 United States
 Email: fgalligan@google.com
Westin, et al. Standards Track [Page 27]